US3244877A

US3244877A - Adjustable specimen holder for an electron microscope with heat conducting feathered leaf springs

Info

Publication number: US3244877A
Application number: US174200A
Authority: US
Inventors: Herrmann Karl-Heinz; Loebe Wolfram; Wilke Felix
Original assignee: Siemens Corp
Current assignee: Siemens and Halske AG; Siemens Corp
Priority date: 1961-02-28
Filing date: 1962-02-19
Publication date: 1966-04-05
Anticipated expiration: 1983-04-05
Also published as: DE1165780B; NL273485A

Description

Aprll 5, 1966 KARL-HEINZ HERRMANN ETAL 3,244,877

ADJUSTABLE SPECIMEN HOLDER FOR AN ELECTRON MICROSCOPE WITH HEAT CONDUCTING FEATHERED LEAF SPRINGS Filed Feb. 19, 1962 2 Sheets-Sheet l 6 'l ,2, 77 5 J///% E//////// Hi a \ JHHHHHHI \\\\\\\w MAM d 14/42 April 5, 1966 ADJUSTABLE SPECIMEN HOLDER FOR AN ELECTRON MICROSCOPE WITH HEAT CONDUCTING FEATHERED LEAF SPRINGS KARL-HE|NZ HERRMANN ETAL 3, 7

2. Sheets-Sheet 2 I N VEN TORS ZZ/A /Z//Z- 7 K ATTORNEYS United States Patent many Filed Feb. 19, 1962, Ser. No. 174,200 Claims priority, application7Germany, Feb. 28, 1961,

s tllaims. cl. zso-ias The invention disclosed herein is concerned with an electron microscope equipped with a specimen adjusting table which is not supported symmetrically to the radiation axis, that is, which is adjustable by means of two drives which are arranged within the microscope housing and which act perpendicularly one with respect to the other. Such specimen adjusting tables comprise basically the table proper, which may be termed the table body, in which is arranged a cone for receiving the specimen cartridge, hereinafter briefly referred to as receiving cone.

Undesired motions of the specimen occur disturbingly, especially in the case of electron microscopes which are provided with means for heating the specimen, and also upon employing normal specimen cartridges, such motions being in the latter case caused by the heating of the table body due to the effect of the electron beam, resulting in heat expansion of the table. These specimen motions cease only when a thermal equilibrium is attained between the cartridge, the table and the microscope. The attainment of the thermal equilibrium is in known constructions delayed, particularly as a result of the poor heat conductioin which exists between the table and the microscope.

The above indicated drawbacks are also observed in connection with electron microscopes equipped with the known specimen adjusting tables and provided with means for cooling the specimen.

The object of the present invention is to provide an electron microscope equipped with a specimen adjusting table of the indicated kind, wherein a thermal equilibrium between the cartridge, the table body and the microscope, is quickly attained, thereby reducing the duration and extent of the specimen motions.

This object is, ccording to the invention, realized by the provision of means for drawing oif heat from the specimen table, particularly from the receiving cone, to the microscope, which does not hinder the adjustability of the specimen adjusting table. Such means can be provided, for example, in the form of flexible mechanical connections. A preferred embodiment of the invention comprises a leaf spring which conducts the heat well, and which is constructed feathered to form a plurality of relatively narrow spring fingers so as to provide for good thermal contact with parts of the microscope.

This measure may be supported by arranging the receiving cone in heat insulating manner in the table body. The heat conduction to the table, and therewith the temperature increase thereof which results in heat expansion causing the motion of the specimen, is held as small as possible, owing to the heat insulated arrangement of the specimen cartridge and therewith of the receiving cone in which is arranged the heat source.

Since the specimen adjusting table is disposed within the vacuum space of the electron microscope, the heat insulation between the receiving cone and the table will be best when there is little direct of indirect connection between these two parts which extends over other parts.

In order to construct this ideal case as best as possible, the receiving cone is in a preferred embodiment of the invention by means of screws suspended in heat insulating relation in the table body. Upon using for this purpose screws which are made of a heat insulating material, the receiving cone will have practically no heat conducting connection with the table body. The screws may be arranged so that they permit adjustment of the height of the receiving cone by moving it and therewith the specimen cartridge relative to the table in the direction of the radiation axis.

In order to facilitate the centering of the receiving cone, which is in the described manner suspended in heat insulating relation in the table, there may be provided ring shaped or bar shaped or punctiform webs which are carried by and extend from the surface facing respectively the other part of the receiving cone and/or the table. In a preferred embodiment of this variant of the electron microscope according to the invention, the web is made of heat insulating material, thus also practically excluding heat condition over these centering elements.

It will be understood that the effect of the above indicated measures for avoiding a temperature increase of the specimen table, which results in a disturbing specimen motion particularly in the case of a specimen adjusting table which is not symmetrically supported with respect to the radiation axis, can be supported by likewise heat insulating the specimen cartridge with respect to the receiving cone therefor.

Further details of the invention will now be described with reference to the accompanying drawing showing the parts of the embodiment of an electron microscope which are of interest in connection therewith.

FIGS. 1 and 3 are sectional views;

FIG. 2 shows an elevational view; and

FIG. 4 schematically illustrates an electron microscope with portions thereof broken away.

As will be seen particularly from FIGS. 1, and 3, the specimen adjusting table comprises basically the table body 1 in which is arranged the receiving cone 2 for the specimen cartridge ill. The table It is in known manner equipped with

rollers

3, 3 or the like, such rollers supporting the table with respect to the drives d, d, non-symmetrically to the radiation axis. This is the reason for the tendency of the table body 1, responsive to heating thereof, as a consequence of the heating of the specimen cartridge and heat conduction over the receiving cone, to execute due to heat expansion motions relative to the radiation axis, thereby producing disturbing motions of the specimen.

In order to avoid these motions, there: are provided means which are to serve for the drawing oil of heat from the receiving cone to the microscope. These means comprise leaf springs 5 and 6 which are in this embodiment fastened to the receiving cone 2, the ends of these leaf springs which lie in engagement with the microscope proper being feathered. The advantage of such feathering of the leaf springs is, that a good heat contact is obtained even in the presence of irregularities in the corresponding engagement plane of the microscope.

In the illustrated embodiment, the receiving cone is arranged in the table body 1 in heat insulating manner, by means of screws '7 and 8 which also permit adjustment of the height of the receiving cone and therewith corresponding position of the specimen.

The receiving cone 2, which is in this way in heat insulating manner suspended by the screws which are preferably made of heat insulating material, is for the centering thereof provided with an annular or ring shaped web or rib 9, such rib having a small cross sectional area and lying in engagement with the table 1 only with a cor- (D respondingly small contact surface. It will be seen particularly from FIG. 1, that there is no other connection between the table body 1 and the receiving cone 2, so that the intermediate space between these parts is nearly completely formed by heat insulating vacuum. It will be realized that the annular rib may receive different form and that it need not be made of metal but may form an independent part made of suitable heat insulating material. Likewise, the specimen or object cartridge 10 may be provided with similar ribs or webs 11.

The specimen cartridge (not shown) can be inserted in the described specimen adjustment table in heat insualting manner, thus resulting in a minimum heat conduction from the specimen, which may be heated by suitable means provided in the cartridge, over the receiving cone 2 to the table, thereby assuring quick attainment of the equilibrium between the respective parts and the microscope.

FIG. 4 shows the arrangement of the specimen adjustment table provided according to the invention with means 5 and 6 for leading off heat from the table proper or body 1 of the electron microscope 4d. The table proper in which is inserted the specimen or object cartridge lltl, is situated above the pole piece system 41 of the objective lens, whose winding is designated by the numeral 42. The beam generation system of the apparatus is positioned above the table 1 and primarily cornprises the cathode 43, Wehnett cylinder 44 and the anode 45. The electron beam leaving this system is bundled in a condenser, the pole piece arrangement of which is designated by the numeral 46 and which has the two energizing coils 4'7 and 48.

The invention may also be advantageously used in connection with an electron microscope provided with means for cooling the specimen. A thermal equilibrium will in such case likewise be attained very quickly.

Changes may be made within the scope and spirit of the appended claims which define what is believed to be ew and desired to have protected by Letters Patent.

We claim:

1. An electron microscope with a specimen adjustment table which is supported nonsymmetrically with respect to the radiation axis, said table comprising a table body, and a receiving cone arranged therein for receiving a specimen cartridge, heat conducting feathered leaf springs operatively extending between said table and the adjacent portion of the microscope, for producing a heat-conducting connection between the specimen adjusting table and the microscope, said springs being constructed to permit unrestricted adjustment ofthe specimen adjustment table.

2. An electron microscope according to claim 1, comprising means for arranging said receiving cone in heat insulating manner in said table.

3. An electron microscope according to claim 2, comprising screw means made of heat insulating material for suspending said receiving cone in said table in heat insulating relation with respect thereto.

An electron microscope according to claim 3, wherein said screw means are arranged so as to permit adjustmerit of the height of the receiving cone relative to the table body.

5. 'An electron microscope according to claim 4, comprising means interposed between said table and said receiving cone for centering the latter in the table.

6. An electron microscope according to claim 5, wherein said centering means is made of heat insulating material.

Reterences Cited by the Examiner UNITED STATES PATENTS 2,347,348 4/1944 Young 250--49.5 2,380,209 7/1945 Bachrnan et al. 25049.5 2,728,840 12/1955 Columbe 250--49.5 2,826,701 3/1958 Columbe 25049.5 2,845,540 7/1958 Franken et a1. 250-49.5 2,858,444 10/195 Leisengang 250-495 RALPH G. NILSON, Primary-Examiner.

Claims

1. AN ELECTRON MICROSCOPE WITH A SPECIMEN ADJUSTMENT TABLE WHICH IS SUPPORTED NONSYMMETRICALLY WITH RESPECT TO THE RADIATION AXIS, SAID TABLE COMPRISING A TABLE BODY, AND A RECEIVING CONE ARRANGED THEREIN FOR RECEIVING A SPECIMEN CARTRIDGE, HEAT CONDUCTING FEATHERED LEAF SPRINGS OPERATIVELY EXTENDING BETWEEN SAID TABLE AND THE ADJACENT PORTION OF THE MICROSCOPE, FOR PRODUCING A HEAT-CONDUCTING CONNECTION BETWEEN THE SPECIMENT ADJUSTING TABLE AND THE MICROSCOPE, SAID SPRINGS BEING CON-