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March 11, 1947.
2,417,213
R. G, PlCARD
DEVICE FOR INDIRECT HEATING OF MATERIALS
Filed Dec. 28, 1944
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2,417,213
Patented Mar. 11, 1947
UNITED STATES PATENT OFFICE
2,417,213
DEVICE FOR INDIRECT HEATING OF
MATERIALS
Robert G. Pica-rd, Collingswood, N. 01., assignor to
Radio Corporation of America, a corporation
of Delaware
Application December 28, 1944, Serial No. 570,091
6 Claims. (Cl. 250-495)
1
The present invention relates to the indirect
heating of materials and more particularly to a
means for raising the temperature of specimens
while under examination in electron microscopes,
electron di?i'action cameras, or other vacuum
equipment.
‘
In the examination of specimens in a vacuum,
such as electron microscopes, the temperature of
_
2
sealed by a plate l8 which is welded or otherwise
fastened in place in leak-proof relation.
For generating the heat to be radiated, current
conducting wires 20 are led into the chamber II
and there terminate in a ?lament 2|, preferably
in the shape of a flat spiral which is located in
juxtaposed relation to the lens IS. The wires 20
are in a circuit including a suitable source of cur
rent 23 and a variable resistance 24, the latter
the specimen generally remains substantially
serving to control the heat developed in the ?la
10
constant, which is entirely satisfactory under
ment 2!. When assembled for use as shown in
most observation conditions, but leaves the ob
Fig. l, the lens i6 is in close proximity to the
server uninformed as to how a specimen reacts
specimen carried by the apertured end of the
when its temperature is raised above that exist
specimen holder 25 which enters the opposite side
ing in the vacuum chamber. In other words, it
of the specimen chamber 14. The holder 25 lo
15
is important to know the effect of abnormal tem
cates the specimen in alignment with the beam of
perature upon a material or specimen under ob‘
servation.
Some of the objects of the present invention
are: to provide a device for raising the tempera
electrons from the electron gun 26, which is of
well known form and enters an end of the micro
scope or diffraction camera column. Thus,
while the specimen is subject to the normal heat
ture of a specimen in a vacuum chamber so that 20 of the projected electrons, it can also be heated
it can be examined in this heated condition; to
provide means for indirectly heating a specimen
in a vacuum chamber; to provide an indirect
heating unit which can be readily mounted in
at will by energizing the ?lament 2| thereby to
raise the temperature of the specimen to allow
it to be studied under the changed condition. By
varying the resistance 24 the radiated heat can
an electron microscope or electron diffraction 25 be controlled as desired.
camera in a position to focus heat upon a speci
The specimen holder 25 is moved into the posi_
men for examination purposes; and to provide
tion of focus by means of the controlling meoh~
other improvements as will hereinafter appear.
anism 21, which may be of the type disclosed in
In the accompanying drawings, Fig. 1 repre
the copending application Serial No. 500,620,
30
sents a fragmentary axial section of the column
?led August 31, 1943, by Frank E. Runge for
of an electron microscope showing an indirect
"Electron-optical instruments.” which is assigned
heating unit embodying one form of the present
to the same assignee as the instant application.
invention; Fig. 2 represents a perspective of the
What is claimed is:
unit; and Fig. 3 represents a section on line III
1. An indirect heating unit comprising a closed
35 casing having an aperture in one end, said casing
III of Fig. 1.
Referring to the drawings, one form of the
having a portion arranged to enter the evacuated
present invention comprises a casing l0 forming
chamber of an electron microscope and assume a
a chamber II to be evacuated and having a cap
extension of reduced diameter to provide a De
position with said aperture in juxtaposed rela
tion to a specimen, said portion having a port
ripheral shoulder l2 to abut the gasket i3 and so 40 communicating with the interior of said chamber,
prevent air leakage when the extension enters
the specimen chamber l4 formed in the column
a lens mounted in said aperture, an electrical
?lament in said casing aligned with said lens, and
l5 of the microscope or diffraction camera. When
an electrical circuit including a source of cur
so assembled the gasket I3 is compressed between
rent and leads connected to said ?lament.
45
the shoulder l2 and the column 15 by atmos
2. 'An indirect heating unit comprising a closed
pheric pressure when the chamber 1 4 is exhausted.
casing having an aperture in one end, said casing
The end of the cap extension is apertured and
having a portion arranged to enter the evacu
threaded for adjustably mounting a lens l6, pref
ated chamber of an electron microscope and
erably of the rock salt type or sylvite, for focus
assume a position with said aperture in juxta
ing the heat (infra-red) radiation upon the speci 50 posed
relation to a specimen, said portion having
men. Source of heat may be focused on speci
a
port
communicating with the interior of said
men by cap screw arrangement shown. A port I‘!
chamber a lens mounted in said aperture, an
is provided in the extension so that the chamber
electrical spiral ?lament in said casing aligned
II is also evacuated with the specimen chamber
with and parallel to said lens, and an electrical
55
id. The outer end of the casing 10 is vacuum
2,417,218
3
4
for mounting a specimen in the path of said
circuit including a source of current and leads
connected to said ?lament.
3. An indirect heating unit comprising a closed
beam, means including 9, source of heat to sub
casing having an aperture in one end, said casing ,
ject said specimen to radiated heat, and means
to focus said supplemental heat upon said speci
having a portion arranged to enter the evacuated
men.
6, In a device operating under vacuum con
ditions, the combination of an evacuated cham
her, an electron gun arranged to project an elec
tron beam into said chamber, a holder in said
a lens mounted in said aperture, an electrical 10 chamber for mounting a specimen in the path
of said beam, means including a source of heat
spiral ?lament in said casing aligned with and
chamber of an electron microscope and assume
a position with said aperture in juxtaposed rela~
tion to a specimen, said portion having a port
communicating with the interior of said chamber
parallel to said lens, an electrical circuit includ
ing a source of current and leads connected to
said ?lament, and means in said circuit for vary
ing the voltage applied to said ?lament.
to subject said specimen to radiated heat, and
means to control the temperature of said sup
plemental means.
ROBERT G. PICARD.
16
4. In a device operating under vacuum con
REFERENCES CITED
ditions, the combination of an evacuated cham
ber, an electron gun arranged to project an elec
The following references are of record in the
tron beam into said chamber, a holder in said
file of this patent:
chamber for mounting a specimen in the path 20
UNITED STATES PATENTS
of said beam, and means including a source of
Number
Name
Date
heat to subject said specimen to radiated heat.
2,275,234
Ruedy ____________ __ Mar. 3, 1942
5. In a device operating under vacuum condi
2,309,104
Dircksen et a1. ____ __ Jan. 26, 1943
tions, the combination of an evacuated chamber,
an electron gun arranged to project an electron 25
beam into said chamber, a holder in said chamber
1,594,635
1,533,605
Skogland ________ __ Aug. 3, 1926
Pelton et al. ______ __ Apr, 14, 1925
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