A sample filter holder is disclosed for use with a microscope for holding the filter in a planar condition on the stage of the microscope so that automatic focusing of the microscope can be performed on particle samples dispersed on the filter. The holder includes a base having a well that communicates with an inlet port which is connected to a suction pump. A screen assembly is positioned within the well. The screen assembly includes a disk having a screen positioned on its top surface and secured to the disk at the peripheral edge of the screen. Small bores allow the outer surface of the screen to communicate with the well. The filter is placed on the screen and is held in a flat disposition by the suction forces

Berry, Anthony

Nerren, Billy H.

English

NASA Technical Reports Server

United States Patent 1191 
Berry et al. 
[113 Patent Number: 4,981,345 
[45] Date of Patent: Jan. 1, 1991 
[54] SAMPLE HOLDER SUPPORT FOR 
[75] Inventors: Anthony Berry, Huntsville; B a y  H. 
Nerren, Meridianville, both of Ala. 
[73] Assignee: The United States of America as 
represented by the Administrator of 
the National A ~ M I I ~ ~ C #  and Space 
Administration, Washington, D.C. 
MIcR0sc0PEs 
[21] Appl. No.: 523,675 
[22] Filed: May 15,1990 
[51] Int. (3.5 ...................... G02B 21/26; G02B 21/32; 
B25B 11/00 
[52] US. Cl. ....................................... 3!50/529; 269/21 
[58] Field of Search ............... 350/529, 248, 238, 239, - 350/507, 532, 536; 269/21,22 
~561 References Cited 
U.S. PATENT DOCUMENTS 
3,328,022 6/1967 Miller .................................... 269/21 
4,744,550 5/1988 Oglesbee ............................... 269/21 
4,943,148 7/1990 Mondragon et al. ............... 350/529 
Primary Examiner-Bruce Y. Arnold 
Assistant Exnminer-James Phan 
Attorney, Agent, or Firm-William J. Sheehan; Jerry L. 
Seemann; John R. Manning 
A sample filter holder for use with a microscope for 
holding the filter in a planar condition on the stage of 
the microscope so that automatic focusing of the micro- 
scope can be performed on particle samples dispersed 
on the filter. The holder includes a base having a well 
communicating with an inlet port which is connected to 
a suction pump. A screen assembly is positioned within 
the well. The screen assembly includes a disk having a 
screen positioned on its top surface and secured to the 
disk at the peripheral edge of the screen. Small bores 
communicate the outer surface of the screen with the 
well. The filter is placed on the screen and is held in a 
flat disposition by the suction forces. 
[571 ABSTRACT 
12 Claims, 1 Drawing Sheet 
https://ntrs.nasa.gov/search.jsp?R=19910012232 2020-03-24T06:59:20+00:00Z
U.S. Patent Jan. 1,1991 
,30 
4,981,345 
48 
4.98 1,345 
2 
a planar condition on the stage of a microscope, the 
holding apparatus having a base member adapted to be 
positioned on the stage and having an inlet port commu- 
nicating with a well within the base, the well opening at 
the top of the base for receiving a screen assembly hav- 
ing a planar screen surface which is positioned about the 
opening of the top. The filter pad is disposed on the 
screen assembly and the inlet port of the base is con- 
nected to a source of sub-atmospheric pressure to draw 
a suction at the screen and thus the filter pad. The 
screen includes a plurality of spaced apart apertures so 
that the suction force on the filter is substantially 
equally applied across the surface of the filter to draw it 
against the planar surface of the screen. The filter is 
thereby maintained flat about its entire surface and the 
samples carried on the filter are thus in a substantially 
planar disposition for focusing upon by the microscope 
for analysis and counting without the need for refocus- 
ing at different locations across the filter. 
BRIEF DESCRIPTION OF THE DRAWINGS 
The particular features and advantages of the inven- 
tion as well as other objects will become apparent from 
the following description taken in connection with the 
accompanying drawings, in which: 
FIG. 1 is a perspective view of a microscope includ- 
ing sample holding apparatus constructed in accor- 
dance with the principles of the present invention; 
,- 
1 
SAMPLE HOLDER SUPPORT FOR 
MIcR0sc0PEs 
ORIGIN OF THE INVENTION 
The invention described herein was made by employ- 
ees of the United States Government and may be manu- 
factured and used by or for the Government for Gov- 
ernment purposes without the payment of any royalties 
thereon or therefor. 
BACKGROUND OF THE INVENTION 
This invention relates to microscope sample holder 
supports and more particularly to a support for holding 
the filter pad on which particulate is to be viewed and 
focused through a programmed microscope to permit 
automatic focusing of the particles for analysis and 
counting. 
In the art of microscopic particle analysis the particu- 
late is deposited on a very thin filter pad in the form of 
a disk or wafer which is placed on a support at the 
microscope stage and held in place by mechanical rings 
which are positioned on the edge of the filter pad. Thus, 
the only portion of the filter pad that is held and main- 
tained flat is the edge of the filter pad. State of the art 
high quality microscopes used as an image analyzer for 
particle counting can be programmed to move in three 
planes and has a limited depth of field automatic focus- 
ing capability in the Z-plane. When the microscope 
focuses on or “sees” a particle, it displays it on a screen 
where the size and number of particles can be made 
automatically. However, because of the limited depth 
of field of the automatic focusing features, if the filter 
pad on which the particles are carried is not planar, the 
microscope will not focus properly and thus will not see 
nor count the particles outside of its depth of field. 
Because the filter pads of the prior art were merely 
maintained flat at the peripheral edge, with the edge in 
focus, substantial portions of the remainder of the filter 
pads which are outside the focusing range could not be 
maintained. It has therefore been the practice in the 
prior art to manually focus the microscope in the Z- 
plane and manually refocus after the microscope has 
moved to a different point in the X-Y plane. 
SUMMARY OF THE INVENTION 
Consequently, it is a primary object of the present 
invention to provide a filter pad holder for use with a 
microscope to permit particle analysis to be performed 
automatically, the particles being dispersed on the filter 
It is another object of the present invention to pro- 
vide a sample holder for microscopes that permit a filter 
pad on which the samples are dispersed to be held pla- 
nar so that focusing of the microscope on the samples 
may be readily performed. 
It is a further object of the present invention to pro- 
vide holding apparatus for supporting a filter pad carry- 
ing particles for analysis in a planar disposition for use in 
a microscope having automatic focusing features used 
for particle analysis, the apparatus comprising a base 
carrying a planar screen or plate having apertures on 
which the filter pad is disposed, the base having means 
for communicating the screen with a source of sub- 
atmospheric pressure so that the filter pad is drawn 
against the screen. 
Accordingly, the present invention provides holding 
apparatus for supporting a sample carrying filter pad in 
Pad. 
5 
10 
I5 
20 
25 
30 FIG. 2 is a perspective view of the sample holding 
apparatus illustrated in FIG. 1 at a greatly enlarged 
scale; 
FIG. 3 is a vertical cross sectional view taken 
through the apparatus of FIG. 2 with the coupling 
FIG. 4 is a top plan view of the screen assembly of the 
FIG. 5 is an elevational view of the screen assembly. 
35 removed; 
holding apparatus removed from the base; and 
40 DESCRIPTION OF THE PREFERRED 
EMBODIMENT 
Referring now to the drawings, FIG. 1 illustrates a 
microscope 10 which preferably may be of the type 
which is program driven to move the stage 12 in three 
45 planes and can automatically focus in the Z-plane. The 
microscope per se does not form any part of the present 
invention and the details thereof are not deemed neces- 
sary to the disclosure of the holding apparatus of the 
present invention, the holding apparatus being gener- 
50 ally indicated at 14. The samples, Le., the particles to be 
analyzed and counted are disposed conventionally on a 
filter pad which is a thin disk in the order of 30 microns, 
the filter pad being constructed of selected material 
55 such as acetate, teflon, paper, polyester or other mate- 
rial which is compatible with the liquid solvent in 
which the particles are suspended so that the liquid may 
flow through the filter and leave the particles dispersed 
thereon for sample analysis. As aforesaid, when per- 
60 forming sample analysis and particle counting, unless 
the particles are disposed in a flat or planar disposition 
the automatic focusing feature of the microscope is not 
effective because of the limited depth of field for auto- 
matic focus. In the prior art the filter pad holders were 
65 annular rings which only held the filter pad flat about 
the peripheral edge of the filter so that the automatic 
focusing capability could not be performed and focus- 
ing had to be done manually. 
4 
4,98 1,345 
3 
To overcome this problem of the prior art, the hold- modifications which do not depart from the spirit of the 
ing apparatus of the present invention provides a base invention are intended to be included within the scope 
16 in the form of a block which may be constructed of of the appended claims. 
any convenient material such as stainless steel, the base Having thus set forth the nature of the invention, 
having an inlet port 18 which may be threaded inter- 5 what is claimed herein is: 
nd1Y for receiving a fluid coupling 20. The inkt port 18 1. A sample filter holder for use with a microscope so 
Communicates though a Channel 22 to an annular CaV- that the filter can be maintained in a substantially flat 
itY 24 centrally disposed in the base and which opens disposition, said holder comprising a base having a well 
onto a well 26 which in turn opens Onto and is recessed formed therein, an inlet port communicating with said 
below a Counterbored opening 28 in the upper surface 10 well, a screen assembly having a substantially planar 
30 Of the base. Thus* the well 26 in flow COmmuniCa- filter support surface positioned in said well with said 
coupling is connected to a conduit 32 which in turn is sembly including flow communicating 
connected to a vacuum pump 34 for drawing a sub- said surface with said well, and means for connecting 
l5 said inlet port to a source of suction for drawing said atmospheric pressure or vacuum in the well 26. 
Positioned in the counterbore 28 and resting on a filter against said surface. 
ledge 36 at the junction between the counterbore and a 1, wherein said 
tiOn with the Coupling 20. AS illustrated in FIG. 1, the surface disposed for receiving a filter thereon, said as- 
2. A filter holder as recited in 
tapered 38 Of the 26 is a Screen flow passage means comprises bores extending through 
said screen assembly and communicating with A d  well. 40* the Screen comprising a disk 42 
having a diameter adapted to be received within the 20 
‘Ounterbore 28 and having a thickness so that when 
positioned on the ledge 36 it is disposed slightly below 
the surface 30 Of the base A thin wafer 44 Of fine 
screening material such as a 0.010 inch thick screen 
having pore diameters of approximately 0.0039 inch is 25 
disk 42 coaxial with the disk, the screen having a smaller 
peripheral diameter the disk. Both the disk 42 and 
the screen wafer 44 may be of stainless steel and the 
3. A filter holder as recited in claim 1, wherein said 
base has an upper surface, a peripheral ledge formed in 
said well recessed below said upper surface, said screen 
assembly including a disk positioned on said ledge, and 
a hub 
4. A filter holder as recited in claim 3, wherein said 
said screen being disposed on said disk and secured 
thereto at said peripheral edge* 
5. A filter holder as recited in claim 4, wherein said 
said screen and said disk and communicating with said 
6. A filter holder as recited in claim 5, wherein said 
in said well. 
fastened about its periphery to the upper surface Of the assembly includes a Screen having a peripheral edge, 
of the wafer may be silver 
from the screen 44 is a small diameter hub 46 
extends therefrom and is received within the well 26 
with the cavity 24. me outside diameter of the 
smaller than the diameter of the cavity 24 so that there extending through said hub- 
is a space between the hub and the wall of the 7. In combination with a microscope for analyzing 
cavity. ~ ~ ~ e d  through the 44 and the disk 42 samples dispersed on a filter at the stage of the micro- 
are a plurality of spaced apart bores @, 17 such bores Scope, a holder for supporting said filter in a substan- 
being illustrated including one which extends through 40 tially Planar disposition, said holder comprising a base 
two radially spaced apart locations. n e  diameter ofthe ing with said well, a screen assembly having a substan- 
bores 48 which preferably are formed by drilling is tially planar filter support surface positioned in said well 
approximately 0.06 inch and all but the one in the hub with said Surface disposed for receiving a filter thereon, 
communicates with the well 26, the bore in the hub 45 said assembly including flow Passage means CO~INU& 
communicating directly with the cavity 24. cating said surface with said well, and means for con- 
In use, a filter pad is placed on the upper surface of necting said inlet port to a source Of  suction for drawing 
the screen assembly 40 with substantially the major said filter against said surface. 
portion of the filter disposed on the screen wafer 44. A 8. The combination aS recited in claim 7, wherein said 
vacuum is then drawn by the pump 34 and the vacuum 50 flow Passage means comprises bores extending through 
communicates through the bores @, Some of the vat- said screen assembly and communicating with said well. 
uum being leaked between the Screen wafer 44 and the 9. The combination as recited in claim 7, wherein said 
surface of the disk 42 so that a substantially equalized base has an upper surface, a Peripheral ledge formed in 
sub-atmospheric pressure is applied to the underside of said well recessed below said upper surface, said screen 
the filter through the tiny pores of the screen. Since the 55 assembly including a disk positioned on said ledge, and 
screen 44 is planar, the filter is pulled into a substantially a hub disposed in said well. 
planar disposition so that when the microscope 10 is 10. The combination as recited in claim 9, wherein 
focused on a particle disposed on the filter, the remain- said assembly includes a screen having a peripheral 
ing particles will be within the depth of the field capa- edge, said screen being disposed on said disk and se- 
bilities for the automatic focusing features of the micro- 60 cured thereto at said peripheral edge. 
scope thereby overcoming the difficulties encountered 11. The combination as recited in claim 10, wherein 
in the prior art. said flow passage means comprises bores extending 
Numerous alterations of the structure herein dis- through said screen and said disk and communicating 
closed will suggest themselves to those skilled in the art. with said well. 
However, it is to be understood that the present disclo- 65 12. The combination as recited in claim 11, wherein 
sure relates to the preferred embodiment of the inven- said flow passage means further comprises at least one 
tion which is for purposes of illustration only and not to bore extending through said hub. 
be construed as a limitation of the invention. All such 
to the 3o 
disk. Concentric with the disk 42 at the surface remote flow passage comprises bores extending through 
hub 46, which is approximately 0.3 inch is slightly 35 flow passage means further comprises at least one bore 
the hub 46, and the others being divided along having a Well formed therein, an hdet port COmmUniCat- 
* * * * *  


Sample holder support for microscopes

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