U.S. patent application number 10/769461 was filed with the patent office on 2004-12-16 for automated imaging system and method.
Invention is credited to Affleck, Rhett L., Levin, Robert K., Lillig, John E., Neeper, Robert K..
Application Number | 20040253742 10/769461 |
Document ID | / |
Family ID | 32854497 |
Filed Date | 2004-12-16 |
United States Patent
Application |
20040253742 |
Kind Code |
A1 |
Affleck, Rhett L. ; et
al. |
December 16, 2004 |
Automated imaging system and method
Abstract
An imaging system for automation of sample monitoring includes
an image capture device that cooperates with a lens assembly for
imaging the samples. A translator positions the lens assembly
and/or a sample plate mount for acquisition of the images. Some
embodiments of the system include a light source configured to
provide low temperature, flash illumination of a sample plate.
Inventors: |
Affleck, Rhett L.; (Poway,
CA) ; Levin, Robert K.; (San Diego, CA) ;
Lillig, John E.; (Ramona, CA) ; Neeper, Robert
K.; (Ramona, CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
32854497 |
Appl. No.: |
10/769461 |
Filed: |
January 30, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60444519 |
Jan 31, 2003 |
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60444585 |
Jan 31, 2003 |
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60444586 |
Jan 31, 2003 |
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60474989 |
May 30, 2003 |
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Current U.S.
Class: |
436/165 |
Current CPC
Class: |
G01N 21/253 20130101;
G01N 2035/00455 20130101; G01N 15/1475 20130101; C30B 7/00
20130101; G01N 35/028 20130101; C30B 29/58 20130101; G01N 35/0099
20130101; G01N 2035/0425 20130101; G01N 2015/1493 20130101; G02B
21/0016 20130101; B01L 9/523 20130101; G01N 2035/00881 20130101;
G01N 2035/0463 20130101; G01N 2035/00356 20130101; G01N 2001/4027
20130101; G01N 2035/042 20130101 |
Class at
Publication: |
436/165 |
International
Class: |
G01N 021/03 |
Claims
What is claimed is:
1. An automated imaging system comprising: an imaging device
configured to automatically capture an image of a sample; a lens
coupled to the imaging device; and an automated lens translator
configured to move the lens along a first axis substantially
parallel to the sample.
2. The imaging system of claim 1, further comprising an automated
well plate translator configured to selectively position a well
plate along a second axis substantially perpendicular to the first
axis.
3. The imaging system of claim 1, wherein the lens comprises a
motorized aperture.
4. The imaging system of claim 1, wherein the imaging device
comprises at least one of an automated focus, zoom, and filter
wheel.
5. The imaging system of claim 1, further comprising a polarization
filter disposed between the imaging device and the sample.
6. The imaging system of claim 1, wherein the filter wheel rotates
so that the polarization filter rotates between the imaging device
and the sample to provide varying polarization angles.
7. The imaging system of claim 1, the filter wheel rotates so as to
provide at least 90 degrees variance of rotational angles of the
filter.
8. An imaging system for obtaining images of a sample, the imaging
system comprising a first illuminator placed off an imaging axis of
the imaging system, whereby the illuminator illuminates the sample
from below and at an angle relative to the imaging axis.
9. The imaging system of claim 8, comprising a second illuminator
positioned away from the imaging axis, wherein the second
illuminator is positioned substantially opposite the imaging axis
from the first illuminator.
10. A method of automatically imaging at least one sample in a well
plate, the method comprising: moving the well plate along a first
axis to a position x; moving an imaging device along a second axis
substantially perpendicular to the first axis to a position y; and
capturing an image of at least one sample of the well plate,
wherein the sample is substantially positioned at coordinates
(x,y).
11. An automated sample analysis system comprising: a temperature
controlled cabinet; a plurality of shelves within the cabinet, each
shelf configured to store a sample carrier; a transport assembly,
within the cabinet, configured to retrieve the sample carrier from
one of the shelves and to transport the sample carrier to a
destination; and an imaging system configured to receive the sample
carrier from the transport assembly and to image at least one
sample of the sample carrier.
12. The automated sample analysis system of claim 11, wherein the
transport assembly is configured to transport a source filter from
a storage location to a position between a light source and the
imaging system.
13. The automated sample analysis system of claim 11, wherein the
source filter comprises a polarizing filter.
14. A method of imaging at least one well in a well plate, the
method comprising; storing the well plate on a shelf at a selected
environment; retrieving the well plate from the shelf using an
automated well plate transport assembly; transporting, at the
selected environment, the well plate to an imaging system using the
automated well plate transport assembly; autonomously imaging, at
the selected environment, at least one well in the well plate using
the imaging system; transporting the well plate from the imaging
system to the shelf using the automated well plate transport
assembly; and repositioning the well plate in the shelf.
15. A method of adjusting a light intensity in an automated
crystallization imaging system, the method comprising: charging a
first capacitor; connecting the first capacitor to an illuminator
to generate flash illumination; and controlling a period of time
the first capacitor is connected to the illuminator to adjust the
illumination from the illuminator.
16. The method of claim 15, wherein connecting the first capacitor
to the illuminator comprises activating an SCR connecting the first
capacitor to the illuminator.
17. The method of claim 15, wherein controlling the period of time
the first capacitor is connected to the illuminator comprises
momentarily interrupting a current flow through the SCR using a
second capacitor.
Description
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application No. 60/444519, titled "AUTOMATED SAMPLE ANALYSIS SYSTEM
AND METHOD," filed on Jan. 31, 2003, having attorney Docket Number
DPINTL.012PR, Provisional Patent Application No. 60/444585, titled
"REMOTE CONTROL OF AUTOMATED LABS," filed on Jan. 31, 2003, having
attorney Docket Number DPINTL.014PR, U.S. Provisional Patent
Application No. 60/444586, titled "AUTOMATED IMAGING SYSTEM AND
METHOD," filed on Jan. 31, 2003, having attorney Docket Number
DPINTL.013PR and Provisional Patent Application No. 60/474989,
titled "IMAGE ANALYSIS SYSTEM AND METHOD," filed on May 30, 2003,
having attorney Docket Number DPINTL.015PR, each of which is hereby
incorporated by reference for all purposes.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention is generally related to devices and methods
for capturing and analyzing images of objects in a field of view.
More particularly, the invention is directed to an imaging system
and related methods for automating the detection and analysis of
substances in samples using imaging techniques.
[0004] 2. Description of the Related Technology
[0005] X-ray crystallography is used to determine the
three-dimensional structure of macromolecules, e.g., proteins,
nucleic acids, etc. This technique requires the growth of crystals
of the target macromolecule. Typically, crystal growth of
macromolecules is dependent on several environmental conditions,
e.g., temperature, pH, salt, and ionic strength. Hence, growing
crystals of macromolecules requires identifying the specific
environmental conditions that will promote crystallization for any
given macromolecule. Moreover, it is insufficient to find
conditions that result in any type of crystal growth; rather, the
objective is to determine those conditions that yield
well-diffracting crystals, i.e., crystal configurations that
provide the resolution desired to make the data useful. This may
require performance of hundreds of screening experiments, varying
the different conditions, for each macromolecule. In the screening
experiments, samples under investigation are periodically evaluated
to determine if suitable crystallization of the sample has taken
place.
[0006] Heretofore, the conventional systems and methods for
performing these tasks have been mostly manual, or at best involved
only limited automation of some subsystems. In some systems,
monitoring of samples involves an operator performing visual
inspection of the samples under a microscope. In other systems,
monitoring of the samples is accomplished by photographing samples
stored in micro-titer plates. The images of the samples are
captured using a camera in cooperation with a microscope and a
light source.
[0007] Because crystallization is highly sensitive to temperature
conditions, it is very important to provide lighting without adding
energy to the sample. Known systems use incandescent or fluorescent
light sources that remain on for the entire imaging process. To
avoid heating the sample, these systems use heat absorbing filters.
However, this approach nonetheless often results in the exposure of
the sample to excessive heat, as well as in the reduction of
illumination to the sample. Light emitting diodes are sometimes
used to limit the amount of heat transferred to the sample, but the
diodes provide light only at a single wavelength and in
insufficient quantity. In these situations, expensive camera
systems are often used to compensate for the diminished spectrum
and quantity of light. Since a large depth of field is preferable
in photographing the samples, it is sometimes necessary to use a
small aperture in the lens. However, this requires compensation by
providing additional light, which means further undesired heating
of the sample.
[0008] Consequently, there is a need in the industry for devices
and methods that enhance the automation of monitoring the
crystallization of substances for use in crystallographic
analysis.
SUMMARY OF THE INVENTION
[0009] The inventive systems and methods disclosed here have
several aspects, no single one of which is solely responsible for
the desirable attributes of the systems and methods. Without
limiting the scope of the invention as expressed by the claims
which follow, its more prominent features will now be discussed
briefly.
[0010] In general terms, the invention concerns an imaging system
and related methods for automating the task of monitoring
crystallization of samples for use in crystallographic analysis.
The imaging system receives sample plates at a plate mount. The
system moves the plate into position so that a camera can take a
picture of the sample through a microscope positioned over the
sample. A light source provides illumination of the sample. Control
circuitry and logic of the imaging system allows automatic
monitoring of each well in a sample plate. The imaging system
stores and analyzes the images captured by the camera to produce
the best possible image of the sample. An operator, or a software
module, may then analyze the images to characterize the crystal
growth in the sample in any given well of the sample plate.
[0011] In one embodiment, an automated sample analysis system for
incubating and analyzing multiple samples for, e.g., protein
crystallization, includes an imaging system. A temperature
controlled cabinet houses sample storage, transport, and imaging
systems. The system is automated and can be controlled by software,
preferably running on a processor external to the cabinet that can
be reconfigured remotely. The system can include an array of
storage shelves having multiple shelf columns arranged around a
core. Each shelf can store a multi-well plate. The core houses a
sample transport system that includes a multi-axis robot that
rotates about a vertical axis to access the shelves in the shelf
array. The transport system retrieves and replaces the multi-well
plates in the shelves and can move plates from the shelves to the
imaging system where each sample can be automatically imaged.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The above and other aspects, features, and advantages of the
invention will be better understood by referring to the following
detailed description, which should be read in conjunction with the
accompanying drawings, in which:
[0013] FIG. 1A is a high-level block diagram of an imaging system
according to the invention.
[0014] FIG. 1B is high-level block diagram of another imaging
system according to the invention.
[0015] FIG. 2 is a perspective view of an imaging system according
to the invention.
[0016] FIG. 3 is a perspective view of the imaging system shown in
FIG. 2, viewed from a different angle.
[0017] FIG. 4 is a perspective view of the imaging system shown in
FIG. 2, viewed from yet a different angle.
[0018] FIG. 5 is a plan front view of the imaging system shown in
FIG. 2.
[0019] FIG. 6 is a plan, right side view of the imaging system
shown in FIG. 2.
[0020] FIGS. 7A and 7B are perspective views from different angles
of a lens system as can be used with the imaging system shown in
FIG. 2.
[0021] FIG. 8 is a perspective view from below of a photo-filter
carriage that can be used with the imaging system shown in FIG.
2.
[0022] FIG. 9 is a perspective view of certain components as
assembled in the imaging system shown in FIG. 2.
[0023] FIG. 10 is a plan front view of certain components as
assembled in the imaging system shown in FIG. 2.
[0024] FIG. 11 is a plan, right side view of the components shown
in FIG. 10.
[0025] FIG. 12 is a perspective view of a light source as can be
used with the imaging system shown in FIG. 2.
[0026] FIG. 13 is a perspective view of a sample mount with the
light source shown in FIG. 12, viewed from a different angle.
[0027] FIG. 14A is a plant top view of the light source shown in
FIG. 12.
[0028] FIG. 14B is a cross-sectional view along the plane A-A of
the light source shown in FIG. 14A.
[0029] FIG. 15 is a exploded, perspective view of certain
components of the sample mount and the light source shown in FIG.
13.
[0030] FIG. 16 is a functional block diagram of an illumination
duration control circuit as can be used with the light source shown
in FIG. 12.
[0031] FIG. 17 is a functional block diagram of an automated sample
analysis system in which the imaging system according to the
invention can be used.
DETAILED DESCRIPTION Of CERTAIN INVENTIVE EMBODIMENTS
[0032] Embodiments of the invention will now be described with
reference to the accompanying figures, wherein like numerals refer
to like elements throughout. The terminology used in the
description presented herein is not intended to be interpreted in
any limited or restrictive manner, simply because it is being
utilized in conjunction with a detailed description of certain
specific embodiments of the invention. Furthermore, embodiments of
the invention may include several novel features, no single one of
which is solely responsible for its desirable attributes or which
is essential to practicing the inventions herein described.
[0033] The imaging system disclosed here is an automated assembly
that positions a sample plate and obtains images of samples stored
in the wells of the plate. In some embodiments, the imaging system
stores the images in a digital storage device for further
analysis.
[0034] FIG. 1A is a high-level block diagram of an imaging system
100. In this embodiment, the imaging system 100 has an assembly 105
that is controlled by controllers and logic 110. The assembly 105
includes a stage 115 that holds and transports target samples to be
imaged by an image capture device 120. The imaging system 100
employs an optics assembly 125 to enhance the view of the target
samples before the image capture device 120 obtains the images of
the samples. An illuminator 130 is configured as part of the
assembly 105 to direct light at the samples held in the stage
115.
[0035] The assembly 105 also includes a translator 135 that
provides the structural support members and actuators to move any
one combination of the stage 115, image capture device 120, optics
125, or illuminator 130. The translator 135 may be configured to
move the combination of components in one, two, or three
dimensions. As will be discussed in detail below, in some
embodiments the stage 115 remains stationary while the translator
135 moves the image capture device 120 and optics 125 to a desired
well position in a sample plate held by the stage 115. In other
embodiments of the imaging system 100, the translator 135 moves the
stage 115 in a first axis and the image capture device 120 and
optics 125 in a second axis which is substantially perpendicular to
the first axis.
[0036] The controllers and logic 110 of the imaging system 100
provide instructions to and coordinate the activities of the
components of the assembly 105. The controllers may include a
microprocessor, controller, microcontroller, or any other computing
device. The logic includes the instructions to cause the controller
to perform the tasks or processing described here.
[0037] FIG. 1B is high-level block diagram of an imaging system
150. The imaging system 150 includes an assembly 155 in
communication with controllers and logic 160. The assembly 155 may
also be in communication with a data storage device 190, which
itself may be configured for communication with the controllers and
logic 160. The controllers and logic 160 control and coordinate the
activities of the components of the assembly 155.
[0038] In this embodiment, the assembly 155 includes a sample plate
mount 165 suitably configured to receive micro-titer plates of
various configurations and sizes. Alternatively, the sample plate
mount 165 can be configured to receive any sample matrix that
carries samples, regardless of whether the samples are stored in
individuals sample wells, rest on the surface of the sample matrix
(e.g., as droplets), or are embedded in the sample matrix. A source
of flash lighting 180 is arranged to direct light bursts to the
samples stored in the micro-titer plate carried by the sample plate
mount 165. An inventive system and method of providing the flash
lighting 180 will be discussed with reference to FIG. 16.
[0039] The assembly 155 includes a compound lens 175 that
cooperates with a digital camera 170 to acquire images of the
samples in the sample plate. The compound lens 175 may consist, for
example, of an objective lens, a zoom lens, and additional optics
chosen to provide the digital camera 170 with the desired image
from the light from the samples. In one embodiment, as will be
discussed further below, the compound lens 175 may be motorized
(i.e., provided with one or more actuators) so that the controllers
and logic 160 can automatically focus the scene, zoom on the scene,
and set the aperture.
[0040] In this embodiment, the assembly 155 includes an x-y
translator that moves either the sample plate mount 165 or the
compound lens 175, or both. Of course, if the digital camera 170 is
coupled to the compound lens 175, the x-y translator moves both the
digital camera 170 and the compound lens 175. In some embodiments,
the x-y translator 185 is configured to move the sample plate mount
165 in two axis, e.g., x and y coordinates. Alternatively, the x-y
translator 185 moves the compound lens 175 in two axis, while the
sample plate mount 165 remains stationary. In yet another
embodiment, the x-y translator consists of multiple and separate
actuators that move independently from one another the sample mount
165 or the compound lens 175.
[0041] It should be noted that the assembly 155, the controllers
and logic 160, and the data storage 190 are depicted as separate
components for schematic purposes only. That is, in some
embodiments of the imaging system 150 it is advantageous to, for
example, integrate the data storage device 190 into the assembly
155 and to include the controllers and logic 160 as part of one or
more of the components shown as being part of the assembly 155.
Similarly, the sample mount 165, digital camera 170, compound lens
175, flash lighting 180, and x-y translator 185 need not all be
configured as part of a single assembly 155 as shown.
[0042] Exemplary ways of using and constructing embodiments of the
imaging system 100 or 150 will be described in detail below with
reference to FIGS. 2-16, which depict a specific embodiment of the
imaging system. Of course, since there are multiple ways to
implement the imaging system, the following description of the
specific embodiment should not be taken to limit the full scope of
the inventive imaging system.
[0043] Illustrative Embodiment
[0044] With reference to FIGS. 2-6 and 9-11, perspective and plan
views of an imaging system 200 according to the invention are
illustrated. The imaging system 200 includes a sample plate mount
210 that receives a sample plate 212. An x-translator having an
actuator 218 (see FIG. 4) is coupled to the sample plate mount 210
to move the sample plate mount 210 into position above a light
source 216 and below a lens assembly 230. A digital camera 214 is
coupled to the lens assembly 230 to capture images of the wells in
the sample plate 212. A y-translator having an actuator 220 (see
FIG. 3) is coupled to the lens assembly 230 to move the lens
assembly 230 into position over a desired well of the sample plate
212.
[0045] Support Platform
[0046] The digital camera 214, lens assembly 230, sample plate
mount 210, light source 216, x-translator 218, and y-translator 220
are mounted on a platform 240 (see FIG. 2). The platform 240
generally consists of several structural members, brackets, or
walls, e.g., base 242, side wall 244, front wall 250, bracket 252,
bracket 246, post 248, and support member 254. The light source 216
can be fastened to the base 242. Rails 256 and 258, which support
the lens assembly 230 are fastened to the wall 250 of the platform
240 and to the support member 254. The sample plate mount 210 is
supported by a rail 262 and an outport guide 253 of the support
member 254. The rail 262 is supported through attachment to the
side wall 244 and the post 248. Of course, there are multiple,
equivalent alternatives to providing support for and configuring
the lens assembly 230, sample plate mount 210, light source 216,
and x-, y-translators 218 and 220 on the platform 240.
[0047] The platform 240 may be constructed of any of several
suitable materials, including but not limited to, aluminum, steel,
or plastics. Because in some applications it is critical to keep
vibration of the platform 240 to a minimum, materials that provide
rigidity to the platform 240 are preferred in such applications.
With regard to the rails 256, 258, and 262, these are preferably
manufactured with very smooth surfaces to carry the lens assembly
230 or the sample plate mount 210 in a smooth fashion, thereby
avoiding vibrations. As illustrated in FIGS. 3 and 9, supporting
the lens assembly 230 may be done by coupling the linear plain
bearings 264 and 266 to the rails 256 and 258. A similar coupling
using a "bushing" 267 (see FIG. 10) may be employed to fasten the
sample plate mount 210 to the rail 262. Bearings 264, 266, and 267
are chosen to provide smooth bearing surfaces for smooth
translation of the load, e.g., the lens assembly 230 or the sample
plate mount 210.
[0048] Sample Plate Mount
[0049] The sample plate mount 210 may be constructed from any rigid
material, e.g., steel, aluminum, or plastics. Preferably the sample
plate mount 210 is configured to accommodate, either directly or
through the use of adapters, various standard sizes of micro-titer
plates. Micro-titer plates that maybe used with the sample plate
mount 210 include, but are not limited to, crystallography plates
manufactured by Linbro, Douglas, Greiner, and Corning. As will be
described further below, the sample plate mount 210 is coupled to
an actuator 218 for moving the sample plate mount 210 in one
axis.
[0050] Translators
[0051] The imaging system 200 includes two independent translators.
Typically, the sample plate mount 210 and the lens assembly 230
move on a plane that is substantially parallel to a plane defined
by the sample plate 212 carried by the sample plate mount 210. In
one embodiment, the controllers and logic 110 or 160 can control
x-, y-translators to position the sample plate mount 210 and the
lens assembly 230 at the coordinates of a specific well of the
sample plate 212.
[0052] An x-axis translator for moving the sample plate mount 210
consists of an actuator 218 (see FIG. 4) that rotates a threaded
rod 219 (or "lead screw") about its axis in clockwise or
counter-clockwise directions. In the embodiment shown in FIGS. 3,
4, and 10, the actuator 218 is coupled to the rod 219 via a belt
(not shown) and pulleys 221 and 221'. The sample plate 210 mount is
fastened to a "bushing" 267 (see FIG. 10) that rides on the rail
262. The sample plate mount 210 is also supported by the outport
guide 253 (see FIGS. 6 and 11) of the support member 254. The
"bushing" 267 is additionally coupled in a known manner to the rod
219. When the actuator 218 turns in one direction, its power is
transmitted via the belt and pulleys 221 and 221' to the rod 219,
which then moves the "bushing" 267 and, thereby, moves the sample
plate mount 210 in a linear direction.
[0053] A y-axis translator for moving the lens assembly 230
consists of an actuator 220 (see FIG. 3) that rotates a threaded
rod 260 about its axis in clockwise or counter-clockwise
directions. In the embodiment shown in FIGS. 3, 6, and 9, for
example, the actuator 220 is coupled to the rod 260 through a
slotted disc coupling (not shown). The lens assembly 230 is coupled
to bearings 264 and 266 that respectively ride on rails 256 and
258. The bearings 264 and 266 are coupled to the rod 260 through
plate 255 and the bracket 257 (see FIG. 6) in a known manner. When
the actuator 220 turns in one direction, its power is transmitted
via the slotted disc coupling to the rod 260, which then moves the
bearings 264 and 266 and, thereby, moves the lens assembly in a
linear direction.
[0054] The actuators 218 and 220 may be direct current gear motors
or 3-phase servo motors, for example. Of course, the type of motors
employed as the actuators 218 or 220 will depend on, among other
things, the weight of the sample plate mount 210 plus sample plate
212 or the lens assembly 230 and the digital camera 214. Another
factor in determining the type of motor is the desired speed. In
one embodiment, actuators 218 and 220 having a positioning
precision of 10-microns are used. Suitable motors may be obtained
from PITMANN of Harleysville, Pa.
[0055] In the embodiment of the x-, y-translators described above,
each translator mechanism independently translates along an axis of
motion each of the sample plate mount 210 and the lens assembly
230. However, it should be noted that in other embodiments of the
imaging system 200, it may be desirable to maintain the lens
assembly stationary and only move the sample plate mount 210, which
would then have one or more translators to position the sample
plate mount 210 anywhere in an x-y coordinate area. Similarly, the
imaging system 200 may be configured so that an x-y translator (or
set of x-, y-translators) moves the lens assembly in the x-y
coordinate area, while the sample plate mount 210 remains
stationary over the light source 216. In one embodiment, the x-,
y-translators employ optical sensors 285 and 287 (see FIG. 5) as to
sense the start or end positions ("home positions") of the lens
assembly 230 or the sample plate mount 210.
[0056] In yet another embodiment, the imaging system 200 may also
include a z-axis translator (not shown) to lift or lower the sample
plate mount 210, lens assembly 230, or light source 216. The z-axis
translator may consist of, for example, an actuator, a lead screw,
one or more rails, and appropriate bearings and fasteners.
[0057] The actuators 218 and 220 may be governed by a controller
(not shown). Suitable controllers may be obtained from J R Kerr
Automation Engineering of Flagstaff, Ariz. The controller may be
configured to interpret high level commands from a computing
device. In one embodiment, when a specific axis is addressed, the
controller causes the actuator 220, for example, to move and keeps
count of the travel distance and final location. The controller can
be programmed to move the actuator 220 at varying speed, torque,
and acceleration.
[0058] Image Capture Device
[0059] In some embodiments of the imaging system 200, the image
capture device can be a film camera, a digital camera, a CMOS
camera, a charge coupled device (CCD), and the like, or some other
apparatus for capturing an image of an object. The embodiments of
the imaging system 200 described here employ a digital camera 214.
A suitable digital camera 214 is, for example, a CMOS digital
camera. However, it should be apparent that several digital
photography devices could also be employed. The CMOS camera 214 is
preferred because it provides random access to the image data and
is relatively low cost. In conventional imaging systems for
crystallography, a CMOS camera is typically not used because in
those systems the level of light is insufficient for this type of
camera. In contrast, the imaging system 200 is configured to
provide the level of light necessary to allow use of a CMOS
camera.
[0060] The digital camera 214 can be a CMOS camera having a pixel
resolution of 1280.times.1024 pixels, Bayer color filter, a pixel
size of 7.5.times.7.5 microns, and a data interface governed by the
IEEE 1394 standard (commonly known as "Firewire"). The digital
camera 124 may be fully digital and not require a frame grabber.
The digital camera 124 may also have a centered pixel area, e.g. a
1024.times.1024 or 800.times.600 pixel subset of the array, which
enhances the image quality since the edges of the array where
optical distortions increase are avoided. In one embodiment, the
digital camera 214 is connected separately to a host computer (not
shown) via a Firewire data interface. This allows for rapid
transfer of large amounts of image data, e.g., five images per
second.
[0061] Lens Assembly
[0062] One embodiment of the lens assembly 230 includes an
objective lens 231, a zoom lens 233, and an adapter 235. These
optical components are chosen to provide suitable field of view,
magnification, and image quality. The objective lens 231, zoom lens
233, and adapter 235 may be purchased from, for example, Navitar
Inc. of Rochester, N. Y.
[0063] In one embodiment, the zoom lens 233 may be the "12X
UltraZoom" zoom lens manufactured by Navitar. The zoom lens 233 may
provide a 12:1 zoom factor, a focus range of about 12-mm, and an
aperture of about 0.14. The zoom lens 233 preferably includes
adapters for mounting the objective lens 231. The zoom lens 233 may
have actuators 233A, 233B, and 233C for providing, respectively,
automatic aperture adjustment, autozoom, and autofocus
functionality. In one embodiment, actuators 233B and 233C have gear
reductions of 262:1. Of course, the gear reduction ratio is chosen
to suit the particular application. For example, a 5752:1 gear
ratio for the focus actuator 233C may be too slow for some
applications of the imaging system 200. The actuators 233A, 233B,
and 233C may be obtained from Navitar or from MicroMo Electronics,
Inc. of Clearwater, Fla.
[0064] The objective lens 231 may be, for example, a 5X Mitutoyo
Infinity Corrected Long Working Distance Microscope Objective
(model M Plan Apo 5) microscope accessory. The objective lens 231
is coupled to the zoom lens 233. Since the light source 216
delivers sufficient light to the sample plate 212, the lens
assembly 230 is configured to allow for setting a small aperture in
order to increase the depth of field. The objective lens 231
preferably provides a working distance that allows adequate room
beneath the lens assembly 230 to manipulate a sample plate 212 and
provide a photo-filter carriage 237 in the image path. In one
embodiment, the working distance of the objective lens 231 is about
34-mm.
[0065] The adapter 235 serves to allow use of the digital camera
214. The adapter 235 may be, for example, a 1X Adapter model number
1-6015 sold by Navitar. Of course, different combinations of
objective lenses 231 and adapters 235 may be used, e.g., a 2X
Adapter and 2X Objective combination. The combination of 1X Adapter
and 5X Objective provides a suitable image for most applications of
the imaging system 200. In some embodiments, it is desirable to use
a 0.67X Adapter 235 with a 10X Objective 231, for example, to
provide a higher image resolution.
[0066] The optical components of the lens assembly 230 can be
provided with actuators for remote and automatic control. To allow
software control of the optical components, controllers and control
logic (not shown) can control the actuators 233A, 233B, 233C, and
233D. The actuators (e.g., dc motors) may be coupled to the
aperture of the, magnification and focus of the zoom lens 233, as
well as the photo-filter carriage 237. In some embodiments, the
actuators 233A, 233B, 233C, and 233D are preferably provided with
encoders to provide position information to the controllers. In one
embodiment, the actuators on the lens assembly 230 are 17-mm direct
current motors with 100:1 gear reducers. These motors may be
obtained from PITMANN.RTM. of Harleysville, Pa.
[0067] The lens assembly 230 may also include a photo-filter
carriage 237 that is configured to hold optical filters (not
shown). For example, the photo-filter carriage 237 can hold
polarization plates or color light filtering plates. FIG. 8
illustrates one embodiment of a photo-filter carriage 237 that may
be used with the imaging system 200. The photo-filter carriage 237
includes a filter wheel 237A for receiving one or more
photo-filters (not shown) in openings 237B. The photo-filters may
be held in place in the filter wheel 237A in a variety of ways. For
example, in the embodiment illustrated in FIG. 8, caps 237C in
cooperation with suitable fasteners hold the photo-filters in
place. The filter wheel 237A may be coupled to an actuator 233D for
remote and automatic control of the filter wheel 237A. The actuator
233D and the filter wheel 237A may be fastened, in a conventional
manner, to a clamp 237D that is coupled to, for example, the
objective lens 231 or the zoom lens 233 (see FIGS. 1 and 9). In one
embodiment, a polarization filter is coupled to a filter wheel so
that the polarization filter covers about 90 degrees of the wheel.
In this embodiment, the polarization filter can be rotated so that
the applied polarization varies between zero and ninety degrees.
Thus, the use of the polarization filter with a polarized light
source can provide analysis of the effect of samples on polarized
light. For example, when a polarized light source and the
polarization filter are cross-polarized then minimal light should
get to the objective lens 231, unless the sample re-orients the
polarized light, such as can happen when the light passes through
crystals.
[0068] The digital camera 214 in combination with the lens assembly
230 provides a broad depth of field to allow imaging of objects
such as protein crystals at varying depths within a sample droplet
stored in a sample well of a sample plate 212. In one embodiment,
the lens assembly 230 has a 12:1 zoom lens and, in cooperation with
the digital camera 214, can provide a 1 micron optical resolution.
In some embodiments, the lens assembly 230 and the digital camera
214 may be integrated as a single assembly.
[0069] Light Source
[0070] The light source 216 will now be described with reference to
FIGS. 12-15. FIG. 12 shows a perspective view of the light source
216. Since the crystallization of substances is often highly
sensitive to temperature changes, the light source 216 is
preferably configured to minimize the amount of heat transferred to
the sample plate 212, e.g., by isolating and removing heat
generated by the electronics 1408 and illuminators 1402 (see FIG.
14B).
[0071] Housing
[0072] With reference to FIGS. 12, 14B and 15, the light source 216
includes a housing 1202 adapted to store one or more illuminators
1402 (see FIGS. 14B and 15), cooling elements 1404, heat reflecting
glass 1406, light diffuser plate 1206, and corresponding
electronics 1405 and 1408. In one embodiment, the housing 1202
consists of a plurality of walls that serve as structural support
for the internal components and that substantially isolate the
internal components from the external environment. The housing 1202
can be constructed of a variety of materials including, but not
limited to, stainless steel, aluminum, and hard plastics. A
material with a low coefficient of heat transfer is preferred so as
to substantially keep heat generated within the housing 1202 from
reaching the outside through the walls of the housing 1202.
However, depending on the application, use of metals is appropriate
when cooling elements 1404 are provided. In some embodiments, one
or more of the internal surfaces of the walls of the housing 1202
may be coated with a suitable material that absorbs or reflects
various types of radiation and prevents them from reaching the
outside of the housing 1202.
[0073] In the embodiment of the light source 216 shown in FIGS.
12-14B, the top wall 1204A of the housing 1202 has an opening to
receive and support a light diffuser plate 1206. The plate 1206
serves to diffuse light from the illuminators 1402 onto the sample
plate 212. The plate 1206 may be, for example, a sheet of
translucent plastic. In one embodiment, inside the housing 1202 and
adjacent and below the plate 1206, a heat reflecting glass ("hot
mirror") 1406 (see FIG. 14B) is provided. The heat reflecting glass
1406 prevents most infra-red energy from exiting the housing
1202.
[0074] The wall 1204B of the housing 1202 may be provided with a
plurality of orifices 1208 that allows a cooling element 1404, such
as fan, to draw air into the housing 1202 for cooling the internal
components. A wall 1204C (see FIG. 14B) of the housing 1202 can be
fitted with an opening 1410 for receiving a duct that guides forced
air out of the housing 1202. A wall 1204D (see FIG. 13) of the
housing 1202 can be fitted with a power plug 1208 communications
port 1302. The housing 1202 is preferably adapted to isolate an
operator of the imaging system 200 from high voltages that may be
used to fire the illuminators 1402.
[0075] Of course, the housing 1202 may be configured in a variety
of ways not limited to that detailed above. For example, the
ventilation openings 1208 on wall 1204B may be replaced by one or
more fans built into the wall 1204B or the wall 1204E. Moreover,
depending on the specific location of the light source 216 in any
given application of the imaging system 200, the ventilation
openings 1208 may be located on the bottom wall (not shown) of the
housing 1202, for example.
[0076] Illuminators
[0077] With reference to FIGS. 14B and 15, the light source 216
includes one or more illuminators 1402 that generate light rays.
The illuminators 1402 may be, for example, incandescent bulbs,
light emitting diodes, or fluorescent tubes of various types
including, but not limited to, mercury- or neon-based fluorescent
tubes. In one embodiment, the illuminators 1402 are two xenon
tubes. Xenon tubes are well known in the relevant technology and
are readily available. The xenon tubes 1402 can include
borosilicate glass that absorbs ultra-violate radiation. Xenon
tubes are preferred because they produce sufficient light to allow
use of a CMOS camera 214 in the imaging system 200. Xenon tubes are
also preferred since they provide a broad spectrum of light rays,
which enables use of color to enhance detection of crystal growth
in the wells of the sample plate 212.
[0078] The actual dimensions of the illuminators 1402 are chosen to
suit the specific application. For example, in the imaging system
200 the xenon tubes 1402 are long enough to cover one dimension of
the sample plate 212 so that it is not necessary to move the light
source 216 when the lens assembly 230 or sample plate mount 210 are
repositioned. As shown in FIG. 14B, the illuminators 1402 may be
supported on a board 1405, which may also support electronics for
control of the illuminators 1402.
[0079] Off-axis Lighting
[0080] In one embodiment, two illuminators 1402 are positioned to
provide both on-axis and off-axis lighting of the wells in the
sample plate 212. As used here, the imaging axis of the lens
assembly means the principal axes of the lens assembly. For
example, first and second xenon tubes 1402 can be positioned,
respectively, a first and second distance from the imaging axis of
the lens assembly 230. Typically, the first and second distances
are substantially equal in length, and the first xenon tube is
positioned opposite the imaging axis from the second xenon
tube.
[0081] In one embodiment, the xenon tubes 1402 are mounted about an
inch on either side of the area directly under the lens assembly
230. This configuration allows the use of an indirect lighting
effect when only one xenon tube is fired. That is, when two xenon
tubes are positioned off the imaging axis, the controllers and
logic 110 or 160 can control the tubes to provide on-axis or
off-axis illumination of the sample plate 212. One xenon tube can
be fired to provide off-axis illumination of the sample plate 212.
When the two xenon tubes are fired simultaneously a more
conventional backlit scene is obtained. In some applications,
off-axis illumination is preferred because it produces shadows on
small objects in a sample droplet stored in a well of the sample
plate 212. The shadows caused by off-axis lighting enhance the
ability of the controllers and logic 110 or 160, or an operator, to
detect objects in the sample.
[0082] In one embodiment, for example the imaging system 150 shown
in FIG. 1B, the controllers and logic 160 control the assembly 155
to capture two images of a droplet in a well plate of the sample
plate 212. The imaging system 150 captures one image with the light
source 216 lighting the sample with a first xenon tube. The imaging
system 150 captures a second image with the light source 216
lighting the sample with the second xenon tube. The controllers and
logic 160 can then combine the data from both images and perform an
analysis based on the combined data. This results in enhanced
characterization of the sample since the combination of the images
typically provides more information about crystallization of the
sample than a single image acquired with standard back lighting of
the scene.
[0083] Filters
[0084] In one embodiment, a source filter 270 (FIG. 2) may be
inserted in a filter slot 272 so that the filter 270 is interposed
between the light source 216 and the sample plate 212. The various
filters 270 may be inserted and removed from the filter slot 272 by
a plate handler. Thus, the filter 270 may be automatically removed,
or exchanged with another filter, by the imaging system 200. The
source filter 270 may be any type of filter, such as a wavelength
specific filter (e.g. red, blue, yellow, etc.) or a polarization
filter.
[0085] Flash Mode
[0086] In one embodiment of the imaging system 200, the light
source 216 includes one or more illuminators 1402 (e.g.,
fluorescent tubes) adapted to provide flash lighting. That is the
illuminators 1402 are controlled to illuminate only momentarily the
sample plate 212 as the digital camera 214 captures an image of a
well in the sample plate 212. This arrangement provides benefits
over known devices in which illuminators remain in the on-position
throughout the entire time that the sample plate 212 is handled by
an imaging system. In the imaging system 200, since the
illuminators 1402 are turned on for only a fraction of a second per
image, very little heat radiation is transferred to the wells of
the sample plate 212. Hence, one benefit of this configuration is
that the imaging system 200 can provide high illumination levels
for the camera 214 while minimizing energy or radiation transfer to
the samples in the sample plate 210. An exemplary control circuit
1600 that provides controlled flash lighting is described below
with reference to FIG. 16.
[0087] Flash Lighting Circuitry
[0088] FIG. 16 is a functional block diagram of an illumination
duration ("flash") control circuit 1600 for an illuminator 1402.
Although only one illuminator 1402 and control circuit 1600 is
shown, multiple illuminators 1402 can be used and independently
controlled using additional control circuits 1600. The illuminator
1402 can be, for example, a xenon tube having a length greater than
the maximum width of the sample plate 212 to be used in the imaging
system 100, 150, or 200. By having such a dimension, the
illuminator 1402 can be located underneath and along one axis of
the sample plate 212 to illuminate all the wells in one row or
column of the sample plate 212 without repositioning the
illuminator 1402.
[0089] A first end of the illuminator 1402 is connected to a first
capacitor 1602 and a first resistor 1604. The opposite end of the
first resistor 1604 is connected to a power supply 1606. The power
supply 1606 may be controlled by a dedicated RS232 line, for
example. The opposite or second end of the first capacitor 1602
that is not connected to the illuminator 1402 is connected to
ground or a voltage common.
[0090] The second end of the illuminator 1402 is connected to the
anode of a first silicon controlled rectifier ("SCR") 1607 and a
first terminal of a second capacitor 1608, respectively. An SCR is
a solid state switching device that can provide fast, variable
proportional control of electric power. A resistor 1620 is
connected between the first terminal of the second capacitor and
the cathode of a second SCR 1610. The second terminal of the second
capacitor 1608 is connected to an anode of the second SCR 1610. The
cathode of the first SCR 1607 is connected to the ground or voltage
common potential. The cathode of the second SCR 1610 is connected
to the cathode of the first SCR 1607 and is similarly connected to
ground or the voltage common potential. The anode of the second SCR
1610 is also connected to a second resistor 1614 that connects the
anode of the second SCR 1610 to the power supply 1606.
[0091] A trigger 1612 of the illuminator 1402 is connected to the
gate of the first SCR 1607 so that both can be triggered
simultaneously. This common connection controls the trigger 1612 of
the illuminator 1402 and the start of illumination. The gate of the
second SCR 1610 controls a stop or end of illumination.
[0092] The duration of illumination provided by the illuminator
1402 can be controlled as follows. Initially, the first and second
SCRs 1607 and 1610, respectively, are not conducting. The first
capacitor 1602 is charged up to the level of the voltage of the
power supply 1606 using the first resistor 1604. The power supply
1606 can, for example, charge the first capacitor to 300 volts or
more.
[0093] The size of the first capacitor 1602 relates to the amount
of energy that can be transferred to the illuminator 1402. The
illuminator 1402 provides an illumination based in part on the
amount of energy provided by the first capacitor 1602. The first
capacitor 1602 can be one capacitor or a bank of capacitors. The
first capacitor 1602 can be, for example, a 600 .mu.F
capacitor.
[0094] The size of the resistors 1620 and 1614 are determined in
part by the desired voltage rise time on the second capacitor 1608.
Smaller resistors 1620 and 1614 allow the second capacitor 1608 to
charge quickly. However, the second SCR 1610 can inadvertently
trigger if the voltage impulse at its anode is too great. Thus, the
value of the resistors 1620 and 1614 are typically chosen to allow
the second capacitor 1608 to recharge before the next image flash
trigger, but not to recharge so quickly as to inadvertently trigger
conduction in the second SCR 1610.
[0095] The resistor 1620 provides an electrical path from the anode
of the first SCR 1607 to ground or voltage common to allow the
second capacitor 1608 to charge.
[0096] The illuminator 1402 is ready to trigger once the first
capacitor 1602 is charged. The second capacitor 1608 is charged by
the power supply 1606 through the second resistor 1614 concurrent
with the charging of the first capacitor 1602. The second capacitor
1608 is chosen to be large enough to generate a current potential
that shuts off the first SCR 1607 and, thus, to terminate
illumination by the illuminator 1402. The second capacitor 1608 can
be a single capacitor or can be a bank of capacitors. The second
capacitor 1608 can be, for example, a 20 .mu.F capacitor.
[0097] After the first and second capacitors 1602 and 1608 have
been charged, the duration of illumination can be controlled. The
illuminator 1402 initially illuminates when the trigger signal is
provided to the control of the illuminator 1402 and the gate of the
first SCR 1607. The illuminator 1402 can include a triggering
circuit that triggers the illuminator 1402 in response to a logic
signal. If the illuminator 1402 does not include this circuit, an
external triggering circuit can be included.
[0098] The first SCR 1607 conducts in response to the trigger
signal. The first SCR 1607 then continues to conduct even in the
absence of a gate signal. The first SCR 1607 can be shut off by
interrupting the current through the SCR or by reducing the voltage
drop across the first SCR 1607 to below the forward voltage of the
device.
[0099] The second SCR 1610 is controlled by a stop signal generator
1616 to connect the second capacitor 1608 in parallel with the
first SCR 1607. However, the second capacitor 1608 is charged in
opposite polarity to the voltage drop across the first SCR 1607.
Thus, when the second SCR 1610 initially conducts, the voltage from
the second capacitor 1608 is placed in opposite polarity across the
first SCR 1607 thereby shutting off the first SCR 1607.
[0100] After the first SCR 1607 is triggered by a gate signal and
begins to conduct, the second end of the illuminator 1402 and the
first terminal of the second capacitor 1608 are pulled to ground
via the first SCR 1607. The illuminator 1402 then illuminates in
response to the current flowing through the illuminator 1402. The
second SCR 1610 controls turn-off of the illuminator 1402. The
second SCR 1610 begins to conduct when a stop signal is applied to
the gate of the second SCR 1610. This pulls the second terminal of
the second capacitor 1608 to ground. Because a capacitor resists
instantaneous voltage changes, the voltage across the second
capacitor 1608 momentarily causes the voltage at the anode of the
first SCR 1607 to be pushed below the ground or voltage common
potential. A negative voltage at the anode of the first SCR 1607
results in a loss of current flowing through the first SCR 1607,
which results in shut down of the first SCR 1607. The second
capacitor 1608 discharges almost immediately. The illuminator 1402
shuts off when the first SCR 1607 turns off because there is no
longer a current path through the illuminator 1402.
[0101] Thus, a microprocessor, controller, or microcontroller can
be programmed to control the trigger 1612 and stop signal generator
1616. The processor controls the trigger signal to initiate
illumination with the illuminator 1402. The processor then controls
the stop signal to control termination of the illuminator 1402. The
processor can thus control the trigger and stop signals to control
the duration of the illumination. The processor can control the
duration of the illumination (a "flash") in predetermined intervals
or can control the duration of the illumination over a range of
time. For example, the processor can control the duration of the
flash in microsecond steps across an interval of approximately 20
.mu.S - 600 .mu.S. Alternatively, the processor can control the
lower range of the duration of the flash to be 0, 20, 40, 50, 75,
100, 150, 200, 250, 300, 350, 400, 450, 500, or 550 .mu.S. In
another alternative, the processor can control the upper range of
the duration of the flash to be 40, 50, 75, 100, 150, 200, 250,
300, 350, 400, 450, 500, 550 or 600 .mu.S. In one embodiment, the
digital camera 214 issues the signal to turn on the illuminator
1402 so that the "flash" will be in synchronization with the
electronic shutter of the digital camera 214.
[0102] The power supply 1606 can be a controllable high voltage
power supply. The microprocessor, controller, or microcontroller
can also control the output voltage of the power supply 1606 to
further control the illumination provided by the illuminator 1402.
For example, the microprocessor can control the output voltage of
the power supply 1606 to vary the illumination provided by the
illuminator 1402 for the same illumination duration. Thus, for a
given illumination duration, the microprocessor can control the
power supply 1606 to a lower output voltage to minimize the
illumination. Similarly, for the same illumination duration, the
microprocessor can control the power supply 1606 to a higher output
voltage, thereby increasing the illumination.
[0103] The microprocessor can control the output voltage of the
power supply 1606 over a range of, for example, 180-300 volts. The
illuminator 1402 may not consistently illuminate for voltages below
180 volts when the illuminator 1402 is a xenon flash tube. The
microprocessor can control the output voltage of the power supply
1606 using a digital control word. Thus, the microcontroller can
control the output voltage of the power supply 1606 in steps
determined in part by the number of bits in the control word and
the tunable range of the power supply 1606. The microcontroller
can, for example provide a 10-bit control word, an 8-bit control
word, a 6-bit control word, a 4-bit control word, or a 2-bit
control word. Alternatively, the power supply 1606 output voltage
can be continuously variable over a predetermined range.
[0104] Thus, the microcontroller can control a level of
illumination by controlling the illumination duration, the power
supply 1606 output voltage, or a combination of the two. The
microprocessor's ability to control the combination of the two
permits a wider range of brightness outputs than if only one
parameter were controllable. The microprocessors ability to control
both illumination duration and power supply 1606 output voltage is
advantageous for different lens zoom conditions. When magnification
is low, such as when the lens is zoomed out, a relatively small
amount of light is required. When magnification is high, a
relatively large amount of light is required to capture an image.
Use of filters and varying apertures may also be used to adjust the
amount of light from the light source.
[0105] Operation
[0106] The imaging system 200 includes software modules that
control and direct the lens assembly 230 to perform the following
functions. In one embodiment, the imaging system 200 is configured
to automatically control the brightness of the image. For example,
after the camera 214 captures an image of a well of the sample
plate 212, the software determines whether the brightness is within
predetermined thresholds. If the brightness does not fall within
the thresholds, the controllers and logic of the imaging system 200
iteratively adjust the illumination intensity of the illuminators
1402 to adjust the brightness of the images until the brightness
falls within the thresholds. In some embodiments, the brightness of
the image may be evaluated based on a predetermined region (or set
of pixels) of the image captured.
[0107] The imaging system 200 can also be configured with software
to automatically focus the image. An exemplary autofocus routine is
as follows. Once the lens assembly 230 is positioned over a sample
of the sample plate 210, the objective lens 231 is moved along its
imaging axis to a predetermined starting position. The camera 214
then acquires an image of the sample and/or well at that focus
position. In one embodiment, the software obtains a "focus score."
This may be done, for example, by examining the brightness values
of a set of pixels (e.g., a 500.times.3 pixel area) in the captured
image, applying a low pass filter, and computing the sum of the
squares of the differences in brightness of adjacent pixels for the
set of pixels. The position and focus score data points are stored
in an array. The objective lens 231 is moved to the next
predetermined incremental position on its imaging axis, and the
process of acquiring an image, computing the focus score, and
storing the position and focus score values is repeated. This
process continues until the objective lens 231 has been moved to
all the predetermined or desired positions, e.g., until it reaches
a predetermined end position by incrementally moving in a
predetermined step size from the starting position. In one
embodiment, the step size depends at least in part upon a
predetermined maximum number of images to be acquired during the
autofocus routine.
[0108] Next, the software searches the lens position/focus score
array to identify the lens position with the best focus score. In
one embodiment, the software then proceeds to compute the lens
positions that are midway from the best focus score position to
positions adjacent to it in the array. That is, the software
examines the array of positions already imaged, finds the nearest
position greater than the lens position associated with the best
focus score, and calculates a "midpoint" position between them. A
similar process is performed with regard to the nearest lens
position that is less than the best focus score position. The
software then acquires images at the midpoint positions and obtains
corresponding focus scores. The software once again evaluates the
array to identify the image with the best focus score, using a step
size that is, say, one-half of the initial step size. These tasks
are repeated until, for example, a maximum number of images
acquired during autofocus, or a minimum step size, has been
reached.
[0109] In some embodiments, the imaging system 200 performs the
processes of autofocusing and automatically adjusting the
brightness, as described above, for each sample of a sample plate
212 received by the imaging system 200. After the desired
brightness and focus are set, the imaging system 200 then captures
an image and stores it in, for example, the data storage 190. In
one embodiment, the automatically determined brightness and focus
are also stored for each sample. In another embodiment, the
software of the imaging system 200 calculates and stores a value
associated with the mean of the brightness and focus positions for
the aggregate of samples of the first plate. This value is then
associated with each of the position/focus score data points in the
array. Subsequent plates are examined using the mean brightness and
focus as initial imaging values.
[0110] The imaging system 200 may also include additional
functionality related to automatically finding the edges of a
droplet in a well of a sample plate 212. In one embodiment, after
the edges of the drop have been found, the imaging system 200 finds
the centroid of the droplet and moves the lens assembly 230 to the
centroid. The imaging system 200 then determines the magnification
required to image substantially only that area corresponding to the
droplet, adjusts the zoom, and acquires the image.
[0111] In another embodiment, the imaging system 200 may be
configured to perform automatic adjustment of aperture. In this
embodiment, the imaging system 200 receives settings for either
maximum image resolution or maximum depth of field. The imaging
system 200 then determines the corresponding aperture by, for
example, looking at one or more tables having values correlating
aperture with maximum resolution and/or maximum depth of field. Of
course, magnification data may be part of these tables.
[0112] In yet another embodiment, the imaging system 200 may be
configured to perform automatic zoom of a substance in a sample
stored in a well of the sample plate 212. In one embodiment, for
example, the imaging system identifies a "crystal-like object" in
the sample, calculates its centroid, moves the lens assembly 230
and digital camera 214 to the centroid, adjusts the zoom level, and
captures an image of the "crystal-like object." In another
embodiment, the imaging system 200 can be configured to capture an
image of a sample or a crystal-like object, perform image analysis
of the image, adjust imaging parameters (e.g., focus, aperture,
zoom, illumination filtering, image filtering, brightness, etc.)
and retake an image of the sample or crystal-like object. The
imaging system 200 can perform this process iteratively until
predetermined thresholds (e.g., contrast, edge detection, etc.) are
met.
[0113] Thus, in one embodiment of the imaging system 200, the
imaging system receives a sample plate 212 and for each sample
performs the following functions including, automatic adjustment of
brightness and aperture, autofocus, automatic detection of the
sample droplet, and acquisition and storage of images. The imaging
system 200 stores the aperture, brightness, focus position, drop
position and/or size. The imaging system 200 may then use mean
values of these factors as initial imaging settings for subsequent
plates.
[0114] To increase the amount of data available for analysis of the
sample, or crystal detection, in some embodiments an illumination
source filter 270 (FIG. 2) may be inserted in the filter slot 272
so that the filter 270 is interposed between the light source 216
and the sample plate 212. In one embodiment the various filters 270
may be inserted and removed from the filter slot 272 by a plate
handler. Thus, the filter 270 may be automatically removed or
exchanged by the imaging system 200. Alternatively, or
additionally, an image filter (such as those that may be placed in
the photo-filter carriage 237) may be interposed between the sample
droplet in the sample plate 212 and the objective lens 231. In one
embodiment, the image filter includes a polarization filter that
provides a variable amount of polarization on the light incident on
the objective lens 231. The use of these filters can be
automatically controlled by imaging software routines and/or
determined by operator defined variables.
[0115] The motorized control of aperture, focus, and zoom of the
lens assembly 230 in conjunction with remote control of the light
source 216 (e.g., brightness and direction of illumination) allows
dynamic optimization of contrast, field of view, depth of field,
and resolution.
[0116] Imaging System Integrated With Automated Sample Analysis
System
[0117] FIG. 17 depicts a functional block diagram of an automated
sample analysis system 1700 having an imaging system 100, 150, or
200. The system 1700 includes controllers and logic 1760 for
controlling various subsystems housed in a cabinet 1702. The system
1700 can further include a shelf access door 1712 for allowing
access to a removable shelf system 1720 and/or a stationary shelf
system 1722. In one embodiment, a removable shelf access door 1710
can be provided. The system 1700 can include a transport assembly
1730 that can consist of a plate handler 1732, an elevator assembly
1734, and a rotatable platform 1736. The system 1700 can further
include an environmental control subsystem 1765 that employs a
refrigeration unit 1762 and/or a heater 1764.
[0118] In one embodiment, the system 1700 also includes an imaging
system 200 as has been described in above. The imaging system 200,
having subcomponents 210, 214, 216, 218, 220, and 230, which are
fully detailed above with reference to FIGS. 2-16, can be housed in
the cabinet 1702. This arrangement ensures that the samples in the
sample plates remain at all times within the confines of a
controlled environment. That is, once a sample plate is stored in
the cabinet 1702, it is unnecessary to expose the sample plate to
the environment external to the cabinet since the system 1700 is
capable of automatically (i.e., without operator intervention)
carry out the imaging of the sample within the cabinet 1702.
[0119] Embodiments of an automated sample analysis system 1700
having an imaging system in accordance with the invention are
described in the related United States Provisional Patent
Application entitled "AUTOMATED SAMPLE ANALYSIS SYSTEM AND METHOD,"
having attorney Docket Number DPINTL.012PR, which is referenced
above.
[0120] While the above detailed description has shown, described,
and pointed out novel features of the invention as applied to
various embodiments, it will be understood that various omissions,
substitutions, and changes in the form and details of the device or
process illustrated may be made by those skilled in the art without
departing from the spirit of the invention. The scope of the
invention is indicated by the appended claims rather than by the
foregoing description. All changes which come within the meaning
and range of equivalency of the claims are to be embraced within
their scope.
* * * * *