U.S. patent application number 13/666776 was filed with the patent office on 2013-05-30 for system for cooling a sample in an apparatus for processing the sample.
This patent application is currently assigned to LEICA MIKROSYSTEME GMBH. The applicant listed for this patent is LEICA MIKROSYSTEME GMBH. Invention is credited to Reinhard LIHL, Robert RANNER.
Application Number | 20130133342 13/666776 |
Document ID | / |
Family ID | 48287994 |
Filed Date | 2013-05-30 |
United States Patent
Application |
20130133342 |
Kind Code |
A1 |
LIHL; Reinhard ; et
al. |
May 30, 2013 |
SYSTEM FOR COOLING A SAMPLE IN AN APPARATUS FOR PROCESSING THE
SAMPLE
Abstract
For cooled processing of a sample, a system for cooling the
sample includes a holding device (22) for receiving the sample in a
sample holder (20), as well as a cooling chamber (12) that
surrounds the position (P) of the sample mounted on the holding
device. Provided in the cooling chamber (12) is a window through
which a tool receptacle (16) for receiving a tool (W) for
processing the sample projects into the cooling chamber (12). The
holding device (22) is coolable to a settable temperature by means
of a fluid coolant, and ensures cooling of the sample. For this, a
coolant, e.g. liquid nitrogen, flows through a coolant conduit of
the holding device (22), which conduit is furnished with the
coolant at the input end (31) and opens at the output end (41) into
the cooling chamber (12), which in this fashion is filled with
coolant gas.
Inventors: |
LIHL; Reinhard; (Wien,
AT) ; RANNER; Robert; (Wien, AT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LEICA MIKROSYSTEME GMBH; |
Wien |
|
AT |
|
|
Assignee: |
LEICA MIKROSYSTEME GMBH
Wien
AT
|
Family ID: |
48287994 |
Appl. No.: |
13/666776 |
Filed: |
November 1, 2012 |
Current U.S.
Class: |
62/62 ; 165/80.1;
62/129; 62/407 |
Current CPC
Class: |
G01N 1/06 20130101; G01N
1/42 20130101; B28D 7/02 20130101; B28D 7/043 20130101; B28D 1/003
20130101 |
Class at
Publication: |
62/62 ; 165/80.1;
62/407; 62/129 |
International
Class: |
F28F 9/00 20060101
F28F009/00; F25D 31/00 20060101 F25D031/00; F25D 17/04 20060101
F25D017/04 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 29, 2011 |
AT |
A1762/2011 |
Claims
1. A system for cooling a sample for processing of the sample in a
processing device, comprising: a holding device configured to
receive a sample for processing via a sample holder; a cooling
chamber including a window, the cooling chamber surrounding the
position of the sample mounted on the holding device; a tool
receptacle configured to receive a tool for processing the sample,
the tool receptacle being positionable through the window such that
it projects into the cooling chamber; and wherein the holding
device is coolable to an adjustable nominal temperature by a fluid
coolant, the holding device comprising a coolant conduit through
which the fluid coolant can flow, the coolant conduit having an
input end configured to supply the fluid coolant and an output end
that opens into the cooling chamber.
2. The system according to claim 1, wherein the cooling chamber is
configured to hold in its interior a gas atmosphere that is
constituted by the coolant and surrounds at least the sample.
3. The system according to claim 2, wherein the cooling chamber
comprises, in addition to the window, an opening that is arranged
on the upper side of the cooling chamber, while the cooling chamber
is otherwise substantially closed off with respect to the
environment of the apparatus.
4. The system according to claim 1, wherein the holding device has
a temperature control system configured to guide a liquid cryogen
in the coolant conduit and evaporate it, and configured to guide
only gaseous cryogen into the cooling chamber.
5. The system according to claim 4, further comprising a
temperature sensor associated with the temperature control system,
the temperature sensor arranged at the output end of the coolant
conduit in order to monitor the passage of liquid cryogen.
6. The system according to claim 1, wherein the coolant conduit
comprises at the input end a coolant connector configured to be
connected to a coolant line of an external coolant vessel.
7. The system according to claim 1, wherein the holding device is
arranged on a pivot arm that enables pivoting of the sample around
a pivot axis with respect to the tool receptacle.
8. The system according to claim 7, wherein the pivot arm is
arranged outside the cooling chamber, and wherein a base of the
holding device and/or the sample holder projects through an opening
into the cooling chamber.
9. The system according to claim 8, wherein the opening is
configured to be closed off by a shield that is pivotable together
with the holding device or the sample holder.
10. The system according to claim 7, wherein the coolant conduit
comprises at the input end a coolant connector that is configured
to be connected to a coolant line and is oriented coaxially with
the pivot axis.
11. The system according to claim 10, wherein the pivot arm is held
by a joint located to a first side of the cooling chamber, and the
coolant connector is arranged on a second side of the cooling
chamber, the second side being located opposite the first side.
12. The system according to claim 1, wherein the cooling chamber
together with the holding device and pivot arm are detachably
mountable as an add-on unit on an apparatus for processing samples,
the cooling chamber being detachably connectable to the apparatus
via a connection interface, and the window being provided in the
connection interface.
13. An apparatus for processing samples, comprising: a holding
device configured to receive a sample holder, the sample holder
configured to hold a sample to be processed; an observation device
for observing the sample; a cooling chamber including a window, the
cooling chamber surrounding the position of the sample mounted on
the holding device; a tool receptacle in the cooling chamber
configured to receive a tool for processing the sample, the tool
receptacle being positionable through the window such that it
projects into the cooling chamber; and wherein the holding device
is coolable to an adjustable nominal temperature by a fluid
coolant, the holding device comprising a coolant conduit through
which the fluid coolant can flow and which can be supplied with the
coolant at the input end and opens into the cooling chamber at the
output end
14. A method for cooled processing of a sample in an apparatus for
processing samples, comprising the steps of: receiving a sample to
be processed in a sample holder on a holding device of the
apparatus, the holding device having a coolant conduit including an
input end and an output end which opens into a cooling chamber that
surrounds the sample during processing; cooling the sample via a
fluid coolant flowing through the coolant conduit on the holding
device; and processing the sample with at least one tool clamped in
the apparatus.
15. The method according to claim 14, wherein after cooling the
holding device, the coolant flows into the cooling chamber and
creates a cold gas atmosphere therein.
16. The method according to claim 14, wherein the cooling chamber
contains a gas atmosphere that is constituted by the coolant and
surrounds at least the sample.
17. The method according to claim 14, wherein a liquid cryogen is
guided and evaporated in the coolant conduit of the holding device,
such that only gaseous cryogen travels into the cooling
chamber.
18. The method according to claim 14, wherein the liquid cryogen is
liquid nitrogen.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority of Austrian patent
application number A 1762/2011 filed Nov. 29, 2011, the entire
disclosure of which is incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The invention relates to the processing of samples under
cooled conditions. The invention further relates to a system for
cooling a sample for processing of the sample in a processing
device.
BACKGROUND OF THE INVENTION
[0003] Processing apparatuses of the kind recited are manufactured
for the preparation of samples in particular for producing
microtome sections. For this, for example, tissue samples to be
investigated are embedded in synthetic resin and these samples are
processed by means of a milling cutter into the shape of truncated
pyramids (so-called "trimming"). The samples trimmed in this
fashion are then sectioned in a microtome, with the result that
tissue sections having a thickness in the micrometer or nanometer
range are obtained, which can then be investigated.
[0004] The Applicant has developed a unit suitable for such
purposes, which is described in EP 1 923 686 A2=US 2008-0115640 A1
and is already on the market in an implementation under the
designation "Leica EM TXP." FIG. 1 is a perspective view of this
unit 100. Housed inside a cover 101 is a processing tool (not
visible in FIG. 1; e.g. milling cutter, saw, grinding disc) with
which a prepared sample to be processed (hereinafter a "sample") is
processed. The sample is located, for example, on a sample holder
(not shown) that is held by a sample receptacle 104 and projects
into cover 101 through an opening 105 thereof.
[0005] Cover 101 serves as an accidental contact protector during
sample processing. The lower part of cover 101 can moreover be used
as a collection pan for polishing agent or other liquids that are
directed onto the sample. The upper part of cover 101 is
transparent and removable; it is equipped with a switching element
that interrupts rotation of the tool is the cover is removed.
[0006] Apparatus 100 comprises an observation device 103, for
example a stereomicroscope, that serves for viewing of the sample.
If applicable, a measurement device that enables monitoring and/or
measurement of the sample can be provided in the observation
device. In a preferred variant of the invention, for example, a
measuring eyepiece is used in the stereomicroscope; with this the
sample itself, but also the progress of the processing action, can
be accurately measured. Other systems, such as e.g. video cameras
and the like, can also be utilized as observation device 103.
[0007] To allow the sample to be cooled or lubricated during
processing, unit 101 can be equipped with a pump 106; via an inflow
107a, a cooling or lubricating agent is delivered (from a reservoir
container, not depicted) to pump 106 and is conveyed via an outflow
107b from pump 106 to the sample.
[0008] Sample mount 104 is held in an arm 102 that is pivotable
around a horizontal axis S that extends perpendicular to the
viewing direction of observation device 103. The pivoting of sample
mount 104 by means of the arm allows the sample to be brought into
different working positions, for example a measurement position, a
processing position, and a monitoring position.
[0009] In the processing position (which is not shown in FIG. 1,
but see FIG. 3) the longitudinal axes of sample receptacle 104 and
of the clamping apparatus for the processing tool lie substantially
parallel to one another; in the unit shown, the two longitudinal
axes are then located horizontally. FIG. 1 depicts the monitoring
position, in which sample receptacle 104 is pivoted downward from
the processing position and the sample surface is thus positioned
exactly in the beam path of stereomicroscope 103. This enables
optical monitoring and analysis of the sample surface. The sample
mount is rotatable in sample receptacle 104 around its longitudinal
axis, which extends perpendicular to axis S. The sample can thus be
rotated by means of a rotary knob 108 in such a way that all
regions of the sample can be viewed through stereomicroscope 103,
and/or edges of the sample can be processed. In the additional
measuring position, which is located, for example, approximately
20.degree. above the processing position, precise measurement of,
for example, the sample edges is possible using suitable measuring
apparatuses in observation device 103.
[0010] This known unit of the Applicant is, however, like other
conventional units of this kind, designed principally for
processing hard samples or at least dimensionally stable samples,
and not for processing samples that are soft at room
temperature.
[0011] Processing of samples at low temperatures is described, for
example, in the Applicant's DE 40 28 806 C2=U.S. Pat. No.
5,299,481, which discloses a microtome having a cooling chamber
accessible from above. Cooling of the sample and of other cooled
parts in the cooling chamber occurs here exclusively by way of the
gaseous cryogen with which the chamber is charged. This prevents
the deposition of moisture from the environment onto the sample as
ice (as a result of displacement by the gas), as well as direct
contact by the sample with cooling liquid; but it does considerably
complicate reliable setting of the sample temperature, and limits
the achievable cooling performance.
SUMMARY OF THE INVENTION
[0012] It is therefore an object of the invention to make possible
the processing of samples while the samples are cooled to a desired
settable temperature, while at the same time condensation of
cooling liquid and/or moisture/ice on the sample and the sample
environment is to remain precluded.
[0013] The stated object is achieved by a system for cooling a
sample of the kind mentioned earlier, in that according to the
present invention, the holding device can be cooled to a settable
temperature by means of a fluid coolant, the holding device
comprising a coolant conduit through which the coolant can flow and
which for that purpose is furnished with the coolant at the input
end and opens into the cooling chamber at the output end; in
addition, there is provided in the cooling chamber a window through
which a tool receptacle (of the sample processing apparatus), which
serves to receive a tool for processing the sample, is positionable
in a manner projecting into the cooling chamber, and in that
context usefully is arranged without contact with the chamber.
[0014] The stated object is likewise achieved according to the
present invention, in the context of the processing of samples
under cooled conditions, by a method having the steps of: [0015]
receiving a sample to be processed, in a sample holder, onto a
holding device of the apparatus, [0016] cooling the sample, and
[0017] processing the sample with the aid of at least one tool
clamped in the apparatus, such that sample cooling and sample
processing can of course in most cases be carried out in
overlapping fashion, the sample being cooled via the holding
device, which in turn is cooled by means of a fluid coolant to a
settable temperature, the coolant flowing through a coolant conduit
of the holding device, which conduit is furnished with the coolant
at the input end, and at the output end opens into a cooling
chamber that surrounds the sample during processing.
[0018] This approach allows the stated object to be achieved in
surprisingly efficient fashion. Cooling of the sample occurs not as
a result of contact with coolant, but by heat transfer via the
holding device. The interior of the chamber is filled only with
coolant gas, which serves less for cooling than for the
displacement of (as a rule, moist) ambient air, which avoids
undesired condensation of moisture as ice. The tool as such is not
cooled (only indirectly via the coolant gas inside the chamber);
cooling of the tool is dispensable, and results in a simplification
of the configuration of the apparatus.
[0019] According to an aspect of the invention it is advantageous,
as already indicated, if the cooling chamber is designed to hold in
its interior a gas atmosphere that is constituted by the coolant
and surrounds at least the sample. For this, after cooling the
holding device the coolant can flow into the cooling chamber, and
can create therein a cold gas atmosphere. Outflow of the gas can be
enabled by the fact that the cooling chamber comprises, in addition
to a window, an opening that is arranged on the upper side of the
cooling chamber, although the cooling chamber is otherwise (i.e.
aside from the aforesaid window and the opening) substantially
closed off from the environment of the apparatus. "Substantially
closed off" means here that the chamber comprises no openings that,
when the processing system is in the operating state, permit an
inflow of ambient air or the like, although minor gaps, e.g.
between movable parts, can be permitted if, for example, coolant
gas can penetrate through them to a sufficient extent and thereby
suppress any inflow of gases from outside. The cooling chamber can
thus contain a gas atmosphere that is constituted by the coolant
and surrounds at least the sample.
[0020] In order to allow reliable setting of the temperature of the
sample on the holding device, a temperature control system can be
provided which is designed to guide a liquid cryogen, in particular
liquid nitrogen, in the coolant conduit and evaporate it, and to
allow only gaseous cryogen to travel into the cooling chamber. A
temperature sensor associated with the temperature control system,
which sensor is arranged at the output end of the coolant conduit
in order to monitor the passage of liquid cryogen, is suitable for
preventing the cryogen from traveling in a liquid state into the
cooling chamber.
[0021] For provision of the coolant, the coolant conduit can
comprise at the input end a coolant connector that is designed for
connection of a coolant line of an external coolant vessel.
[0022] In a particularly advantageous refinement of the invention,
the holding device is arranged on a pivot arm that enables pivoting
of the sample around a pivot axis with respect to the tool
receptacle. The pivot arm can be arranged outside the cooling
chamber, such that a base of the holding device and/or the sample
holder projects through an opening into the cooling chamber. This
opening can furthermore be closed off by a shield that is pivotable
together with the holding device or the sample holder. The
previously mentioned coolant connector can moreover be oriented
coaxially with the pivot axis. In a favorable embodiment, the
arrangement of the coolant connector and pivot arm can be such that
the pivot arm is held by a joint located to the side of the cooling
chamber, and the coolant connector is arranged on that side of the
cooling chamber which is located opposite the joint.
[0023] According to a further aspect of the invention, the system
for sample cooling is removable, so that the cooling chamber
together with the holding device and pivot arm is embodied in a
sample cooling arrangement that is removable from the sample
processing apparatus. In the context of a removable system, the
cooling chamber can have a connection interface by way of which it
is detachably mountable on the aforementioned apparatus for
processing samples; the aforesaid window, through which a tool
receptacle projects in the state mounted on the apparatus, is
provided in this context inside the connection interface.
[0024] A further aspect of the invention relates to an apparatus
for processing samples of the kind recited earlier, in which
apparatus the holding device together with a cooling chamber is
embodied in accordance with the above-described system according to
the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The invention, along with further details and advantages,
will be explained below with reference to an exemplifying
embodiment, namely a sample processing apparatus having an
arrangement for sample cooling that is removable as an add-on unit,
which arrangement is shown in the appended drawings. In the
individual drawings, in schematic form:
[0026] FIG. 1 is a perspective view of a processing apparatus of
the existing art;
[0027] FIG. 2 is a perspective view of the processing apparatus in
accordance with the exemplifying embodiment, having a mounted
arrangement for sample cooling in the monitoring position for
observation of the sample;
[0028] FIG. 3 shows the processing apparatus of FIG. 2 in the
processing position;
[0029] FIG. 4 is a perspective view of the arrangement in the
removed state;
[0030] FIG. 5 is a detail view of the arrangement in the processing
position;
[0031] FIG. 6 shows the processing apparatus as in FIG. 3, although
here the arrangement is shown in a sectioned depiction (horizontal
section);
[0032] FIG. 7 shows the arrangement as in FIG. 4, but in a
sectioned depiction with a horizontally extending section
plane;
[0033] FIG. 8 is a perspective view of the cooling block of the
arrangement;
[0034] FIG. 9 is a block diagram of the temperature regulator;
[0035] FIG. 10 is a sectioned view of the coolant pump; and
[0036] FIG. 11 shows the cooling chamber and cooling block in a
further sectioned view with a vertically extending section
plane.
DETAILED DESCRIPTION OF THE INVENTION
[0037] The exemplifying embodiment described below represents a
further development of the unit discussed earlier with reference to
FIG. 1, in which the cover and sample mount are now embodied as a
combinedly removable device with sample cooling. Be it noted that
the embodiment shown is not to be understood as a limitation of the
invention; one skilled in the art can instead effect numerous
variations and configurations of the invention.
[0038] Referring to FIGS. 2 and 3, a sample processing apparatus 10
according to the present invention with sample cooling is shown. In
the Figures, the apparatus is equipped with a removable arrangement
11 for sample cooling, which at the same time contains a cooling
chamber 12 that surrounds the sample during processing; the basic
body of the apparatus corresponds to the sample processing
apparatus (e.g. of the "Leica EM TXP" type) described earlier with
reference to FIG. 1, without cover and sample holder including the
pivot arm. The description given above with regard to the apparatus
of FIG. 1, in particular with regard to the various working
positions and the associated processing of the sample, and to the
observation device (stereomicroscope), thus applies in the same
fashion, aside from the sample cooling made possible according to
the present invention, to the apparatus according to the present
invention, and reference is made in supplementary fashion to the
description in the Applicant's EP 1 923 686 A2 (or US 2008/0115640
A1) and DE 10 2006 054 609 A1 (or US 2008/0118312 A1), both of
which are herewith incorporated in their entirety as part of the
present disclosure.
[0039] Apparatus 10 further comprises, as already mentioned
earlier, an observation device 13 (e.g. stereomicroscope) as well
as a pump 14 with which the sample can be supplied with a liquid
during processing; for processing with grinding discs, for example,
a low-temperature-compatible liquid can be introduced as a grinding
agent for wet grinding. Tube 15 can be guided, on the upper side of
the cooling chamber, through a separate opening in order to bring
the liquid to position P of the sample. The lower part of chamber
12 can in turn serve as a collection pan for said liquid. It is
significant in this context that in the processing position, the
sample and the tool are held in substantially horizontal axes,
since this allows excess grinding liquid to flow off quickly and
decreases undesired deposition of solids.
[0040] Arrangement 11 for sample cooling is shown in FIG. 4 in the
removed state. The removable unit 11 performs essentially two
tasks, for the implementation of which two assemblies respectively
corresponding to the tasks are provided: [0041] 1. Delimiting the
processing space: A cooling chamber 12 comprises a
temperature-regulated outer wall and a shield 29 for sealing the
pivotable sample holder 20. An opening 43 on the upper side of the
chamber allows the prepared sample to be observed, and furthermore
serves to allow evaporated coolant gas to flow out in controlled
fashion. [0042] 2. Prepared sample cooling: A pivot arm 21, which
is pivotable around the horizontal axis S (pivot axis) extending
through the cooling chamber, contains a holding device 22 for
positioning a sample holder 20 (FIG. 5). Holding device 22 is
equipped with a cooling block having flowthrough conduits for a
coolant, preferably a cryogenic liquid such as liquid nitrogen. The
coolant is evaporated and travels into the cooling chamber through
an outlet opening for the cold gas.
[0043] Arrangement 11 thus integrates the components of the system
according to the present invention for sample cooling into a system
that advantageously is removable as a unit.
[0044] Arrangement 11 is mounted on apparatus 10 by means of a
connection interface 17 that is embodied on chamber 12 and that
surrounds a window 47. Upon mounting onto apparatus 10, the chamber
is positioned like a cap over tool receptacle 16, so that the tool
receptacle projects through window 47 into the interior of chamber
12 but without touching components of the chamber. A tool mounted
on tool receptacle 16 can thus move freely inside window 47 to the
extent necessary for processing the sample.
[0045] Arrangement 11 can be brought with the aid of pivot arm 21
into a variety of working positions, e.g. a processing position
(FIG. 3) and a monitoring position (FIG. 2) for observing the
prepared surface of the processed sample. Pivot arm 21 is fastened
pivotably on processing apparatus 10 by way of a joint 23 that is
arranged on one side of cooling chamber 12. In the embodiment
shown, joint 23 is mounted permanently on processing apparatus 10,
and a detachable connecting point is located between the joint and
pivot arm (see FIGS. 4 and 7).
[0046] FIG. 5 is an enlarged partial view of arrangement 11
(mounted on the apparatus) in the processing position, the upper
part of cooling chamber 12 having been removed for clarity (the
removed part is depicted with dashed lines). The previously
mentioned tool receptacle 16, e.g. in the form of a collet chuck,
is provided for receiving a processing tool (at position W), and is
rotatable around its longitudinal axis at a settable rotation
speed, and positionable in the direction of that longitudinal axis.
In addition, the entire tool receptacle 16 can be displaced
laterally with respect to the position of the sample, e.g. for
eccentric grinding; actuation of this displacement motion occurs
laterally on the housing, as described in more detail in DE 10 2006
054 609 A1 or US 2008/0118312 A1.
[0047] The sample is positioned at a predefined position P with
respect to tool W or tool receptacle 16 with the aid of a sample
holder 20. The sample is symbolized here by its position P. Sample
holder 20 is embodied preferably as a separate detachable
component, and is fastened in a holding device 22 so that a sample
present on sample holder 20 is entirely located in the interior of
cooling chamber 12. Holding device 22 is held by pivot arm 21 at a
distance from pivot axis S and comprises a base 25, oriented with
respect to the pivot axis, which projects through a passthrough
opening 42 into chamber 12 and whose inwardly directed end is set
up for fastening and cooling of sample holder 20 together with the
sample.
[0048] Referring again to FIG. 2, arrangement 11 comprises a
connector piece 30 having a connector 31 for the delivery of liquid
nitrogen (LN2) that serves as a coolant. This connector 31 serves
as a coolant connector for detachable connection to a filling hose
(plastic with insulation, of known type). The filling hose is in
communication, for example, with an external coolant reservoir,
e.g. an LN2 dewar.
[0049] FIGS. 6 and 7, in which arrangement 11 is shown in a
sectioned depiction (with a horizontal section plane along pivot
axis S), illustrate the layout of conduit 24 for conveying the
coolant or liquid nitrogen to holding device 22. The liquid
nitrogen travels through connector piece 30 via a hose part 33 into
holding device 22. The connector piece 30, hose part 33, and
holding device 22 are thermally insulated on the outside.
[0050] Connector 31 is preferably embodied coaxially with pivot
axis S, by the fact that is located rotationally symmetrically with
its axis in pivot axis S, and permits a rotation with respect to
base part 32, attached to the chamber, of connector piece 30. The
result is that the hose connector remains stationary even in the
context of rotation of the sample mount; the rotation in connector
piece 30 occurs between base part 32 and the attached part (FIG. 4)
carrying connector 31. The connector connection is thereby
decoupled from pivoting motions of pivot arm 21. This increases
security, avoids damage to the filling hose upon pivoting as well
as undesired motions of the coolant reservoir, and facilitates
stable positioning of the processing apparatus. The connector
connection can be embodied with a non-rotating coolant hose
connection of known type. Connector piece 31 is located on cooling
chamber 12 preferably opposite the position of joint 23 of the
pivot arm.
[0051] The liquid nitrogen flows along conduit 24 through holding
device 22 in a cooling block 26, evaporates there, and travels as a
cold gas through base 25 into cooling chamber 12. The pump for
conveying liquid nitrogen (not shown) is regulated, with the aid of
temperature sensors and using a heating device (see below with
reference to FIG. 9), in such a way that only gaseous nitrogen
travels into the cooling chamber. Gaseous nitrogen has two
advantages: on the one hand, as a cold gas, it cools the chamber
and processing tools. Secondly, the chamber is purged with the dry
gas, and the formation of ice crystals on the cold surfaces and on
the sample is thus prevented. The gas emerges principally via
observation opening 43 located on top.
[0052] FIG. 8 shows cooling block 26 in a separate perspective
view; the left side portion of the cooling block is removed in FIG.
8, and in addition the upper side of the cooling block is removed,
making visible the meandering layout of coolant conduit 24. A
heating cartridge 34 is housed in an orifice 44 of the cooling
block, and a (first) temperature sensor 35 in a second orifice 45.
Multiple orifices are introduced into the body of cooling block 26
on the upper and the lower side of the cooling block, the ends of
each pair of orifices being connected by depressions, with the
result that a conduit extending back and forth between the left and
right side of the cooling block is formed, serving as a coolant
conduit 24. The depressions are closed off by side parts 28 that
are respectively attached on the left and right like a cover, thus
producing a linear conduit that here is split into two branches
(upper and lower branch 24a, 24b). At the outlet end the two
branches of conduit 24 are guided through the base and lead to exit
openings 41 at that end of the base at which sample holder 20 is
also attached. The conduit thus opens at the output end (namely,
with both branches) into coolant chamber 12.
[0053] FIG. 9 is a block diagram of the control system for setting
a desired temperature T of the sample by means of a temperature
control loop having heating system 34 and temperature sensor 35.
This control loop, as well as thermal insulation with respect to
the unit, enables a desired sample temperature to be set, in
conjunction with a control unit (temperature control system 50) for
setting the desired sample temperature with a heat-up function
after processing is complete. The heating system also makes it
possible to avoid condensation of ambient moisture on the outer
side of cooling chamber 12 and holding device 22. An LN2-compatible
coolant pump 51 delivers liquid nitrogen, provided from coolant
reservoir 37, to the cooling block.
[0054] Referring to FIG. 10 (sectioned view), pump 51 is
[?implemented], for example, by means of a membrane pump 52 that is
embodied on cover plate 38 of LN2 reservoir 37 with a pump head 57,
immersed into the coolant, that is located in a manner immersed
into the liquid nitrogen preferably close to the bottom of the LN2
reservoir. As a result of the design selected here, membrane pump
52 is located with its rubber membrane 53 outside the LN2 reservoir
and is separated from the valves in pump head 57 and particular
from the cold liquid. Membrane 53 is moved back and forth by an
eccentric motor 54 (that moves around axis 55). The result is to
produce a moving gas column in pump tube 56 that connects membrane
pump 52 to pump head 57, and a (slight) positive and negative
pressure is thus alternatingly generated in pump headspace 58 at
the end of pump tube 56, with the result that two valves 61, 62
located in pump head 57 alternatingly open and close in order to
convey LN2. Each of the two valves 61, 62 is embodied in the form
of a ball having a conical sealing seat, and in the pressureless
state is closed by the dead weight of the relevant ball. First
valve 61 serves as an inlet valve; it connects between an inlet
opening 60 to the liquid space of reservoir 37 and pump headspace
58, and opens when there is negative pressure in the latter. Second
valve 62, here referred to as a "delivery valve," connects pump
headspace 58 to a riser tube 59; it opens when there is positive
pressure in pump headspace 58. When there is negative pressure in
pump headspace 58, in a first step of a pumping operation liquid
nitrogen flows through the inlet valve. In the next step, when a
positive pressure is produced in pump headspace 58 by membrane pump
52, inlet valve 61 closes while delivery valve 62 is opened, and
the liquid is forced into riser tube 59. When the pump headspace is
once again brought to negative pressure in a new cycle, delivery
valve 62 closes again and the cycle begins ab initio. Riser tube 59
leads through cover plate 38 and opens at its upper end into a
connector 63 for the coolant hose (not shown), which is connected
to connector 31 of sample cooling arrangement 11. The delivery
capacity can thus be very accurately regulated by way of the
rotation speed of membrane pump 52; eccentric motor 54 of the
membrane pump is operated, for example, as a stepping motor. At the
same time, the mechanism of pump head 57 is very robust and
insensitive to temperature changes and icing.
[0055] Nitrogen delivery via coolant pump 51 is controlled as a
function of the setpoint temperature T. The rotation speed ranges
of pump 51 are defined in the software of temperature control
system 50 in such a way that for each settable value of the
setpoint temperature, the liquid nitrogen becomes gaseous within
the meanders of conduit 24. The resulting nitrogen gas is guided
through openings 41 into chamber 12 and acts as a protective gas
against ice deposits on the cold surfaces in the interior of the
chamber. Heating system 35 is operated at only low output, and
serves to increase the control accuracy and temperature
consistency; without a heating system, the temperature would be
several K below the setpoint temperature.
[0056] A second temperature sensor 36, preferably arranged close to
exit openings 41, for example in a separate orifice 46, can be
provided in order to prevent liquid nitrogen from getting into the
cooling chamber, said sensor. If the temperature at temperature
sensor 36 drops below the temperature of liquid nitrogen, or more
precisely to a limit value just thereabove, the nitrogen is
converted into the gas phase by additional heating.
[0057] The chamber and other external surfaces can additionally be
heated in order to prevent the condensation of water.
[0058] FIG. 11 shows arrangement 11 in a sectioned view, with a
horizontal section through the longitudinal axis of the holding
device. In this sectioned depiction, conduit 24 in cooling block 25
is visible in multiply sectioned fashion because of its meandering
layout.
[0059] Consistent with pivotability, a geometry of passthrough
opening 42 for the sample holder as an elongated or slot-shaped
opening is useful. A shield 29 that is prolonged in wing-like
fashion along the pivoting direction on both sides is provided on
base 25 in order to close off opening 42 in the various working
positions. Passthrough opening 42 is closed off by shield 29 in
every pivot position, and undesired emergence of cold gas at this
point is suppressed. Provided at the attachment of shield 29 are
wave spring washers 39 that counteract lifting of the shield away
from the edge of opening 42.
[0060] With the aid of the invention it is possible to process
samples that are too soft for processing at room temperature, by
cooling them to a temperature at which said processing is possible,
for example below an associated glass transition temperature. A
typical temperature range for processing is, for example,
-120.degree. C. to 170.degree. C. Examples of sample materials for
which the invention enables processing are, for example, polymer-
or rubber-based samples (e.g. structures made of wire or the like
embedded in rubber material), as well as biological samples.
[0061] The invention is not to be limited to the specific
embodiments disclosed, and modifications and other embodiments are
intended to be included within the scope of the invention.
PARTS LIST
[0062] 10 Apparatus for sample processing
[0063] 11 Sample cooling arrangement
[0064] 12 Cooling chamber
[0065] 13 Observation device/stereomicroscope
[0066] 14 Pump
[0067] 15 Tube
[0068] 16 Tool receptacle
[0069] 17 Interface
[0070] 20 Sample holder
[0071] 21 Pivot arm
[0072] 22 Holding device
[0073] 23 Joint
[0074] 24 Conduit for coolant
[0075] 25 Base (cooling block)
[0076] 26 Cooling block
[0077] 27 Body (of cooling block)
[0078] 28 Side part (of cooling block)
[0079] 29 Shield
[0080] 30 Connector piece
[0081] 31 Coolant connector
[0082] 32 Base of connector piece
[0083] 33 Hose part
[0084] 34 Heating system/heating cartridge
[0085] 35 First temperature sensor
[0086] 36 Second temperature sensor
[0087] 37 Reservoir
[0088] 38 Cover plate of reservoir
[0089] 39 Wave spring washers
[0090] 41 Exit opening
[0091] 42 Passthrough opening
[0092] 43 Observation opening
[0093] 44, 45, 46 Orifices
[0094] 47 Window
[0095] 50 Temperature control system
[0096] 51 Coolant pump
[0097] 52 Membrane pump
[0098] 53 Membrane
[0099] 54 Eccentric motor
[0100] 55 Eccentric axis
[0101] 56 Pump tube
[0102] 57 Pump head
[0103] 58 Pump headspace
[0104] 59 Riser tube
[0105] 60 Inlet opening
[0106] 61 Inlet valve
[0107] 62 Delivery valve
[0108] 63 Connector for coolant hose
[0109] S Pivot axis
[0110] P Position of sample
[0111] W Tool
[0112] T Setpoint temperature
[0113] 100 Apparatus (existing art)
[0114] 101 Cover
[0115] 102 Arm (pivot arm)
[0116] 103 Observation device/stereomicroscope
[0117] 104 Sample receptacle
[0118] 108 Rotary knob for sample mount
[0119] 105 Opening (in cover)
[0120] 106 Pump
[0121] 107a, 107b Inflow and outflow of pump
[0122] 108 Rotary knob for sample mount
* * * * *