U.S. patent number RE35,868 [Application Number 08/565,580] was granted by the patent office on 1998-08-11 for apparatus for imaging particles in a liquid flow.
This patent grant is currently assigned to Toa Medical Electronics Co., Ltd.. Invention is credited to Tokihiro Kosaka.
United States Patent |
RE35,868 |
Kosaka |
August 11, 1998 |
**Please see images for:
( Certificate of Correction ) ** |
Apparatus for imaging particles in a liquid flow
Abstract
An apparatus for imaging and analyzing particle components in a
sample liquid flow containing particle components such as blood and
urine, or fine particles of organic high polymer in suspension or
the like. A conventional particle imaging flow cytometer is
combined with a light source such as a lamp with small coherence,
and an image intensifier with gate function of high response, so
that a clear particle image without a deflection or interference
fringe is obtained. Thus, in the apparatus having the still imaging
function, by using the image intensifier with a high speed gate
function, even with a light source of a long luminous time such as
a lamp, a clear still image of a particle flowing at high speed is
obtained.
Inventors: |
Kosaka; Tokihiro (Kakogawashi,
JP) |
Assignee: |
Toa Medical Electronics Co.,
Ltd. (Kobe, JP)
|
Family
ID: |
18241947 |
Appl.
No.: |
08/565,580 |
Filed: |
November 30, 1995 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
933737 |
Aug 24, 1992 |
05272354 |
Dec 21, 1993 |
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Foreign Application Priority Data
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Nov 20, 1991 [JP] |
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3-331282 |
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Current U.S.
Class: |
250/574;
356/336 |
Current CPC
Class: |
G01N
15/1427 (20130101); G01N 15/1463 (20130101); G01N
15/1459 (20130101); G01J 2001/4493 (20130101); G01N
2015/1477 (20130101); G01N 2015/1465 (20130101) |
Current International
Class: |
G01N
15/14 (20060101); G01N 015/06 () |
Field of
Search: |
;250/573-575
;356/39,336,338,343 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Allen; Stephone B.
Attorney, Agent or Firm: Jones, Tullar & Cooper,
P.C.
Claims
What is claimed is:
1. An apparatus for imaging particles in a liquid flow, the liquid
flow forming a sheath flow by passing a sheath of liquid around a
sample flow containing particles to be detected, emitting light to
the sample flow, detecting light signals from the particles,
processing the signals in a signal processing unit, and analyzing
the particles, comprising:
a light source for illuminating particles by emitting incoherent
light which does not induce interference, to a sample flow region
of the liquid flow;
an image intensifier for receiving the transmitted light of the
particles in the sample flow region, for intensifying an input,
feeble image, and producing a bright image, said image intensifier
having a shutter;
a video camera for capturing the image of the image intensifier and
generating a video signal;
an image processing unit for processing the video signal from the
video camera;
a signal processing unit; and
detecting means for detecting the existence of particles in the
sample flow region and generating a particle signal S1;
wherein:
the image intensifier is an image intensifier provided with a high
speed gate; and
the signal processing unit generates a trigger signal S2 for
emitting the light from the light source for illuminating a
particle on the basis of the detection of the particle signal S1,
and while the light source is radiating, generating a gate signal
S3 for opening the shutter of the image intensifier.
2. An apparatus for imaging particles in a liquid flow of claim 1,
wherein the light source for illuminating particles is always
radiated, and the signal processing unit generates the gate signal
S3 for opening the shutter of the image intensifier on the basis of
the detection of the particle signal S1.
3. An apparatus for imaging particles in a liquid flow for forming
a sheath flow by passing a sheath of liquid around a sample flow
containing particles to be detected, emitting light to the sample
flow, detecting light signals from the particles, processing the
signals in a signal processing unit, and analyzing the particles,
comprising:
a light source for illuminating particles for emitting incoherent
light to a sample flow region of the liquid flow;
spectral means for dividing the transmitted light of the particles
in the sample flow region into components of three wavelength
regions of red, green and blue;
a plurality of image intensifiers for receiving the transmitted
light from a respective one the divided three components, each
image intensifier having a shutter;
a plurality of video cameras for capturing the images of a
respective image intensifier and each generating a video
signal;
an image processing unit for processing the video signals from the
video cameras as signals R, G, B;
a signal processing unit; and
detecting means for detecting the existence of particles in the
sample flow region and generating a particle signal S1;
wherein;
the image intensifier is an image intensifier provided with a high
speed gate; and
the signal processing unit generates a trigger signal S2 for
emitting the light from the light source for illuminating a
particle on the basis of the detection of the particle signal S1,
and while the light source is being radiated, generating a gate
signal S3 for opening the shutters of the image intensifiers.
4. An apparatus for imaging particles in a liquid flow of claim 3,
wherein the light source for illuminating particles is always
radiated, and the signal processing unit generates the gate signal
S3 for opening the shutters of the image intensifiers on the basis
of the detection of the particle signal S1. .Iadd.5. An apparatus
for imaging particles in a liquid flow, the liquid flow forming a
sheath flow by passing a sheath of liquid around a sample flow
containing particles to be detected, emitting light to the sample
flow, detecting light signals from the particles, processing the
signals and analyzing the particles, comprising:
a light source for illuminating particles by emitting light to a
sample flow region of the liquid flow;
an image intensifier for receiving light of the particles in the
sample flow region, for intensifying an input, feeble image, and
producing a bright image, said image intensifier having a
shutter;
a video camera for capturing the image of the image intensifier and
generating a video signal;
an image processing unit for processing the video signal from the
video camera; and
a signal processing unit wherein:
the image intensifier is an image intensifier provided with a high
speed gate; and
the signal processing unit generates a gate signal for opening the
shutter
of the image intensifier. .Iaddend..Iadd.6. An apparatus for
imaging particles in a liquid flow, the liquid flow forming a
sheath flow by passing a sheath of liquid around a sample flow
containing particles to be detected, emitting light to the sample
flow, detecting light signals from the particles, processing the
signals, and analyzing the particles, comprising:
a light source for illuminating particles by emitting light to a
sample flow region of the liquid flow;
an image intensifier for receiving light of the particles in the
sample flow region, for intensifying an input, feeble image, and
producing a bright image, said image intensifier having a
shutter;
a video camera for capturing the image of the image intensifier and
generating a video signal;
an image processing unit for processing the video signal from the
video camera;
a signal processing unit; and
detecting means for detecting the existence of particles in the
sample flow region and generating a particle signal wherein:
the image intensifier is an image intensifier provided with a high
speed gate; and
the signal processing unit generates a gate signal for opening the
shutter
of the image intensifier. .Iaddend..Iadd.7. An apparatus for
imaging particles in a liquid flow of claim 6, wherein the light
source for illuminating particles is always radiated, and the
signal processing unit generates the gate signal for opening the
shutter of the image intensifier on the basis of the detection of
the particle signal. .Iaddend..Iadd.8. An apparatus for imaging
particles in a liquid flow, the liquid flow forming a sheath flow
by passing a sheath of liquid around a sample flow containing
particles to be detected, emitting light to the sample flow,
detecting light signals from the particles, processing the signals,
and analyzing the particles, comprising:
a light source for illuminating particles by emitting light to a
sample flow region of the liquid flow;
an image intensifier for receiving light of the particles in the
sample flow region, for intensifying an input, feeble image, and
producing a bright image, said image intensifier having a
shutter;
a video camera for capturing the image of the image intensifier and
generating a video signal;
an image processing unit for processing the video signal from the
video camera;
a signal processing unit; and
detecting means for detecting the existence of particles in the
sample flow region and generating a particle signal wherein:
the image intensifier is an image intensifier provided with a high
speed gate; and
the signal processing unit generates a trigger signal for emitting
the light from the light source for illuminating a particle on the
basis of the detection of the particle signal, and while the light
source is radiating, generating a gate signal for opening the
shutter of the image
intensifier. .Iaddend..Iadd.9. An apparatus for imaging particles
in a liquid flow of claim 8, wherein the light source for
illuminating particles is always radiated, and the signal
processing unit generates the gate signal for opening the shutter
of the image intensifier on the basis of the detection of the
particle signal. .Iaddend.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for imaging particles
in a liquid flow, and in particular to an imaging flow cytometer
for imaging and analyzing particle components in a sample liquid
containing particle components such as blood and urine, or fine
particles such as organic high polymer particles in suspension, or
the like, and more particularly to an imaging flow cytometer
capable of obtaining a clear still image of particles flowing at
high speed (for example, 5 m/sec. or more) even with a light source
of a long light emission time such as a lamp, by using an image
intensifier with a high speed gate function, in a flow cytometer
with still imaging function.
To image particles in a sample liquid flowing at a high speed of
several meters per second in a flow cell, using a flow cytometer,
as conventionally shown in FIG. 1, it is generally know to capture
a particle image free of vibration, by the combination of a pulse
laser light source 29 capable of emitting an intense light only for
a moment and a video camera 43. In a flow cell 14, a sheath flow 15
is formed by passing sheath liquid around the sample flow including
the particles 16 to be detected, and this sample fine flow 15 is
illuminated with laser light from an argon laser generator 10. The
light signal (the scattered light or fluorescent light) from the
particle is detected by a light detector (photo-multiplier or the
like) 22, and a signal S1 is sent to a signal processing unit 24 to
be processed, thereby analyzing the particles. The sheath flow is a
flow covered with a laminar sheath liquid around the suspension of
particles in order to pass the particles neatly in one row
precisely in the middle of the liquid flow. Also shown in FIG. 1 is
a pulse emission trigger signal S4, a laser power supply 27, an
image processing unit 46, condenser lenses 12, 31, objective lenses
20, 33, a projection lens 41, and a beam stopper 18.
In the Japanese Laid-open Patent Sho. 62-254037, it is disclosed to
image only particles with specific characteristics, by detecting
the particles by the image pickup device nearly simultaneously, by
providing the flow cytometer with a streak image pickup device, and
processing the imaging signal only when matched with a
predetermined characteristic value. It is also disclosed to use a
high sensitivity camera and a camera tube as the image pickup
device, and picture the entire image instantly.
The Japanese Laid-open Patent Sho. 63-94156 discloses a flow
cytometer in which the light source for detecting particles is
always illuminated, passing of a cell is detected by a cell
detector, and after delaying for a specific time in a delay
circuit, the light source for the laser pulse for imaging is turned
on to picture the cell.
In the conventional particle imaging flow cytometer shown in FIG.
1, sine the laser light source possesses a high coherence, the
interference fringe is often obvious in the obtained particle
image, so that the image quality is not so high. Besides, since the
laser light source presents a monochromatic light, a color image of
the particles is not obtained. Besides, the pulse laser light
source, of the gas type, is large in size, and the power source is
also large in scale, and is very expensive.
By using a xenon flash lamp small in coherence as the light source,
a clear image without an interference fringe may be obtained, but
the luminous time of the xenon flash lamp is generally long, 1
.mu.sec or more, and in this case the image may deviate unless the
sheath flow velocity is 0.3 m/sec. or less. At the flow velocity of
0.3 m/sec., however, the intrinsic high processing ability of the
flow cytometer, that is, the large number of cells analyzed per
unit of time is not achieved.
Besides, neither publication refers to imaging of still pictures of
particles by using in image intensifier with high speed gate, which
is a feature of the present invention.
OBJECT AND SUMMARY OF THE INVENTION
It is hence a primary object of the present invention to provide an
apparatus capable of obtaining a clear particle image without
deflection or on interference fringe, by combining the optical
system of the conventional particle imaging flow cytometer with a
lamp of small coherence and an image intensifier with a gate
function capable of responding at high speed.
To achieve the above object, the present invention provides a first
imaging flow cytometer for forming a sheath flow by passing sheath
liquid around a sample flow containing particles to be detected,
emitting light to this sample fine flow, detecting light signals
from the particles, processing the signals in a signal processing
unit, and analyzing the particles, comprising:
a light source for imaging particles by emitting incoherent light,
that is, light which does not induce interference, to a sample fine
flow region downstream of the detecting region of the particle
detecting light,
an image intensifier to be focused by the transmission light of the
particles in the sample fine flow region,
a video camera for capturing the image of the output plane of the
image intensifier, and
an image processing unit for processing the video signal from the
video camera, wherein
the image intensifier is an image intensifier provided with a high
speed gate, and
the signal processing unit generates a trigger signal S2 for
emitting the light from the light source for imaging a particle by
delaying a specific time from detection of the particle signal S1,
and while the light source is radiating, a gate signal S3 for
opening the shutter of the image intensifier is generated.
The present invention presents a second imaging flow cytometer, in
which, in the first apparatus, the light source for imaging
particles is always radiated, and the signal processing unit
generates a gate signal S3 for opening the shutter of the image
intensifier by a specific time delay from the detection of particle
signal S1.
The present invention also presents a third imaging flow cytometer
for forming a sheath flow by passing sheath liquid around a sample
flow containing particles to be detected, emitting light to this
sample fine flow, detecting light signals from the particles,
processing the signal in a signal processing unit, and analyzing
the particles, comprising:
a light source for image particles for emitting incoherent light to
the sample fine flow region downstream of the detection region of
the particle detecting light,
spectral means for dividing the transmission light of the particles
in the sample fine flow region into components of three wavelength
regions of red, green and blue,
image intensifiers to be focused by the transmission lights divided
in three components,
video cameras for capturing the images of output planes of the
image intensifiers, and
an image processing unit for processing the video signals from the
video cameras as signals R, G, B, wherein
the image intensifiers are image intensifiers provided with high
speed gates, and
the signal processing unit generates a trigger signal S2 for
emitting the light from the light source for imaging a particle by
delaying for a specific time from the detection of the particle
signal S1, and while the light source is being radiated, a gate
signal S3 for opening the shutters of the image intensifiers is
generated.
The present invention also presents a fourth imaging flow
cytometer, in which, in the third apparatus, the light source for
imaging particles is always radiated, and the signal processing
unit generates a gate signal S3 for opening the shutters of the
image intensifiers in a specific time delay from the detection of
the particle signal S1.
The apparatus of the present invention comprises two systems, that
is, the particle detecting system and the particle imaging system.
The particle imaging system is installed at the downstream side of
the particle detecting system in the sample fine flow. When the
particle detection signal S1 is detected, the signal processing
unit generates a trigger signal S2 in a specific time delay, and
the light source for imaging a particle is illuminated to capture a
still image of the particle passing through the sample fine flow by
a video camera. The delay of a specific time is the time required
for the particle to move from the particle detection region to the
imaging region.
In order to obtain a still image of the particle flowing at high
speed, the luminous time must be short. If the luminous time is
long, a blurry image is captured. Besides, a sufficient quantity of
light is also needed.
In the present invention, by generating a gate signal S3 while the
particle imaging light source is emitting light, the image
intensifier is operated to obtain a still image of the particle.
The image intensifier intensifies the input feeble image, and
produces a bright image. The image intensifier with a high speed
gate function operates as an image intensifier only when the gate
signal is ON. Accordingly, regardless of the luminous time of the
light source, by turning on the gate signal for a short time while
the light source is luminous, a bright and sharp still image is
obtained. The still picture obtained by the image intensifier is
captured by the video camera, and processed in the image processing
unit.
In the third apparatus of the present invention, the transmission
light is divided into red, green and blue components, and for these
three images there are three image intensifiers with a high speed
gate and three monochromatic video cameras so that video signals of
R, G, B components are obtained for one image. That is, one color
image is obtained.
In the second and fourth apparatus, by always emitting the imaging
light source, by operating the image intensifier by the gate signal
S3 only when desired to capture, a still image is obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic explanatory diagram of a conventional
apparatus.
FIG. 2 is a schematic explanatory diagram showing an embodiment of
an imaging flow cytometer of the present invention.
FIG. 3 is a schematic explanatory diagram showing another
embodiment of an imaging flow cytometer of the present
invention.
FIG. 4 is a diagram for explaining the timing of each signal in an
imaging flow cytometer of the present invention.
FIG. 5 is a diagram for explaining the structure and operating
principle of an image intensifier.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, some of the preferred embodiments of
the present invention are described in detail below.
FIG. 2 shows an imaging flow cytometer for forming a sheath flow by
passing sheath liquid around a sample flow containing particles 16
to be detected, emitting light to this sample fine flow 15,
detected light signals from the particles, processing the signals
in a signal processing unit 24, and analyzing the particles,
comprising:
a light source 28 for imaging particles by emitting incoherent
light, that is, light which does not induce interference, to a
region of the sample fine flow downstream of the detecting region
of the particle detecting light,
an image intensifier 38 to be focused by the transmission light of
the particles in the sample fine flow region,
a video camera 42 for capturing the image of the output plane of
the image intensifier 38, and
an image processing unit 44 for processing the video signal from
the video camera 42, wherein
the image intensifier 38 is an image intensifier provided with a
high speed gate, and
the signal processing unit 24 generates a trigger signal S2 for
emitting the light from the light source 28 for imaging a particle
by delaying a specific time from detection of the particle signal
S1, and while the light source 28 is illuminating, a gate signal S3
for opening the shutter of the image intensifier 38 is
generated.
In the imaging flow cytometer rated immediately above, the light
source 28 for imaging particles is always radiated, and the signal
processing unit 24 generates a gate signal S3 for opening the
shutter of the image intensifier 38 by a specific time delay from a
the detection of the particle signal S1.
FIG. 3 shows an imaging flow cytometer for forming a sheath flow by
passing sheath liquid around a sample flow containing particles 16
to be detected, emitting light to a sample fine flow 15, detecting
light signals from the particles, processing the signal in a signal
processing unit 24, and analyzing the particles, comprising:
a light source 28 for imaging particles for emitting incoherent
light to a region of the sample fine flow downstream of the
detection region of the particle detecting light,
spectral means 35 for dividing the transmission light of the
particles in the sample fine flow region into components of three
wavelength regions of red, green and blue,
image intensifiers 38a, 38b, 38c to be focused by the transmitted
light divided in three components,
video camera 42a 42b, 42c for capture the images of the output
planes of the image intensifiers 38a, 38b, 38c, and
an image processing unit 45 for processing the video signs from the
video cameras 42a, 42b, 42c as signals R, G, B, wherein
the image intensifiers 38a, 38b, 38c are image intensifiers
provided with high speed gates, and
the signal processing unit 24 generates a trigger signal S2 for
emitting the light from the light source 28 for imaging a particle
by delaying for a specific time from the detection of the particle
signal S1, and while the light source 28 is being radiated, a gate
signal S3 for opening the shutters of the image intensifiers 38a,
38b, 38c is generated.
In the imaging flow cytometer rated immediately above, the light
source 28 for imaging particles is always radiated, and the signal
processing unit 24 generates a gate signal S3 for opening the
shutters of the image intensifiers 38a, 38b, 38c in a specific time
delay from the detection of the particle signal S1.
The apparatus of the present invention comprises two systems, that
is, the particle detecting system and the particle imaging system.
The particle imaging system is installed at the downstream side of
the particle detecting system in the sample fine flow 15. When the
particle detection signal S1 is detected, the signal processing
unit 24 generates a trigger signal S2 in a specific time delay, and
the light source 28 for imaging a particle is illuminated to
capture a still image of the particle passing through the sample
fine flow by a video camera 42. The specific time delay is the time
required for the particle to move from the particle detecting
region to the image capturing region.
In order to obtain a still image of the particle flowing at high
speed the luminous time must be short. If the luminous time is
long, a blurry image is captured. Besides, a sufficient quantity of
light is also needed.
In the present invention, by generating a gate signal S3 while the
particle imaging light source 28 is emitting light, the image
intensifier 38 is operated to obtain a still image of the particle.
The image intensifier intensifies the input feeble image, and
produces a bright image. The image intensifier with a high speed
gate function operates as an image intensifier only when the gate
signal is ON. Accordingly, regardless of the luminous time of the
light source, by turning on the gate signal for a short time while
the light source is luminous, a bright and sharp still image is
obtained. The still image obtained by the image intensifier is
captured by the video camera 42, and processed in the image
processing unit 44.
In the apparatus of FIG. 3, the transmission light is divided into
red, green and blue components, and for these three images there
are three image intensifiers 38a, 38b, 38c each with a high speed
gate and three monochromatic video cameras 42a, 42b, 42c, so that
video signals of R, G, B components are obtained for one image.
That is, one color image is obtained.
In the apparatus of FIGS. 2 and 3, a still image is obtained by
always emitting the imaging light source 28, by operating the image
intensifier by the gate signal S3 only when desired.
The apparatus of FIG. 2 is realized by combining the conventional
image flow cytometer shown in FIG. 1 with the light source 28 for
imaging a particle for emitting incoherent light, and the image
intensifier 38 with high speed gate to be focused by the
transmission light of particles, and others.
As an example of the light source 28 which is small in coherence, a
xenon lamp or a halogen lamp may be used, and the lamp may be
either of the flash emission type or of the continuous emission
type.
The sample flow containing the particle 16 to be detected is led
into a flow cell 14 composed of a transparent material such as
glass and plastic, and a sheath liquid is supplied to cover the
circumference of the sample flow, thereby forming a sheath flow The
laser light from the laser light source 10 is emitted to the sample
fine flow 15 through the condenser lens 12. The light signal
(scattered light or fluorescent light) from the particle is
detected by the light detector 22 through objective lens 20 and
beam stopper 18, and the signal S1 is sent to the signal processing
unit 24 to be processed. The strobe luminous trigger signal S2 from
the signal processing unit 24 is sent to the power supply of strobe
26 to emit the light from the light source 28 for imaging a
particle, and incoherent light is emitted to the sample fine flow
region downstream of the detection region of the particle detection
light through collimator lens 30 and condenser lens 32. The light
transmission from the particle passes through the objective lens 34
and the projection lens 36, and is focused on the photoelectric
plane (input plane) of the image intensifier 38 with high speed
gate function. The image of the output plane of the image
intensifier 38 is projected to the video camera 42 through relay
lens 40 to be captured, and the video signal is sent to the image
processing unit 44 to be processed.
FIG. 5 is a diagram for explaining the operating principle of the
image intensifier 38. The gate function of the image intensifier 38
is realized generally by polarity control of the potential of the
photoelectric plane 50 against the microchannel plate (MCP) 56.
That is, when the potential of the photoelectric plane 50 is
positive, the photoelectrons released from the photoelectric plane
50 not reach the MCP 56, and it thereby serves as a shutter in a
closed state. On the contrary, when the potential of the
photoelectric plane 50 is negative, the photoelectrons reaches the
MCP 56, and the shutter is opened. This response of the gate
function is usually as fast as several nanoseconds. Numerals 52, 54
are electronic lenses, and 58 is a fluorescent plane.
Supposing the sheath flow velocity to be 5 m/sec. and the allowance
of image deflection to be 0.3 .mu.m, the exposure time to the CCD
plane of the video camera is 60 nsec. or less. Hence, by setting
the gate ON time within 60 nsec., a deflection-free particle image
is obtained.
If taken by using an ordinary lamp and video camera in a short
exposure time of 60 nsec. or less, only an almost black image is
obtained, but by adding the image intensifier 38 having a light
amplification power of a thousand to tens of thousands of times, a
bright image is obtained.
The control of the timing for turning on the gate of the image
intensifier 38 is explained by reference to FIG. 4. From the
scattered light or signal S1 of fluorescent intensity obtained from
the detection system as the convention flow cytometer, the particle
is detailed passing through the detection area of the flow cell 14.
Next, waiting until the particle reaches the video camera capturing
area located in the downstream direction of the detection area, the
gate of the image intensifier 38 is turned on for a period of
scores of nanoseconds. When using a lamp of the flash emission
type, first a trigger for illuminating the flash is applied, then
the gate is turned on. The time from the issue of the trigger for
lighting the flash till the gate of the image intensifier 38 is
turned on depends on the delay time t1 from the issue of the
trigger to the lamp till the emission intensity L reaches the peak.
Meanwhile, S2 is a strobe luminous trigger signal, S3 is a gate ON
signal of image intensifier, and tm is the time that the particle
moves from the laser detection area to the video camera capturing
area.
By turning on the gate of the image intensifier 38, photoelectrons
depending an the particles image focused on the photoelectric plane
50 are released, and these photoelectrons are put into the MCP
(microchannel plate) 56, and are amplified several thousand times.
The amplified photoelectrons further excite the fluorescent plane
58 which is the output plane, and a particle image amplified
several thousand times is obtained. The image on the fluorescent
plane 58 is focused on the CCD plane of the video camera 42 through
the relay lens 40 or optical fiber.
The video camera 42 is available in the field cumulative type and
frame cumulative type depending on whether the light cumulative
time is 1/60 sec. or 1/30 sec., and where the vertical resolution
is more important, the frame cumulative type should be used. In
this case, in order to obtain a satisfactory particle still image,
the exposure time by the gate function is limited to only one
exposure in an even-number field period. One exposure means
multiple exposures are prohibited. Therefore, all particles passing
through the flow cell detection unit cannot be taken, and an
application for taking a specific particle only is desired.
As the light source 28 for particle imaging, by using a white light
source such as xenon lamp or halogen lamp, a color image of the
particle difficult to obtain in the conventional laser light source
can be obtained. An embodiment for this purpose is shown, in FIG.
3. Three sets each of image intensifiers each with a gate function
and monochromatic video cameras are provided, and filters or prisms
for separating (resolving) the light from the particle into the
three primary colors of red, green and blue are disposed before the
input planes of the individual image intensifiers 38a, 38b, 38c,
and the image is amplified in each color and is captured by the
video cameras 42a 42b, 42c. The video signals from the individual
video cameras are obtained as color video signals of R (red), G
(green) and B (blue). Numerals 35a, 35b, 35c are spectral means
(for example, dichroic mirrors), and 36a, 36b, 36c are projection
lenses, 40a, 40b, 40c are relay lenses, and 45 is an image
processing unit. The other components and their function are same
as in FIG. 2.
The present invention, being thus constructed, brings about the
following effects.
(1) Using the image intensifier with a high speed response gate, a
blur-less, clear particle image of a particle flowing at high speed
is obtained by a lamp light source of a relatively long luminous
time such as xenon lamp, without using a pulse laser light source
of short luminous time and a large quantity of light.
(2) Since an incoherent light source such as a xenon lamp is used
as the light source, a particle image without interference fringe
may be obtained. The lamp is an inexpensive and small light source,
and the apparatus may be reduced in cost and in size.
(3) When the particle image is separated into red, green and blue
light, and image intensifiers and video cameras are provided for
individual images, a color image which was difficult to obtain in
the monochromatic light (laser light source) can be obtained.
(4) In the apparatus of FIGS. 2 and 3, a blurless, sharp image is
obtained even if the light source for particle imaging is always
radiated.
Having described preferred embodiments of the invention with
reference to the accompanying drawings, it is to be understood that
the invention is not limited to those precise embodiments, and that
various changes and modifications may be effected therein by one
skilled in the art without departing from the scope or spirit of
the invention as defined in the appended claims.
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