PARTICLE-BEAM APPARATUS SUCH AS AN ELECTRON MICROSCOPE OR THE LIKE
United States Patent 3823321
A particle-beam apparatus such as an electron microscope or the like has a housing containing a beam generator for generating a particle beam, and a specimen carrier for receiving a specimen to be investigated in the apparatus. The specimen carrier is penetrable by the beam and is displaceable within the housing transversely to the beam. An adjusting mechanism for effecting the transverse displacement of the specimen carrier is disclosed and includes two pivotally mounted positioning levers having end portions facing the specimen carrier and movable in mutually perpendicular directions. The first positioning lever is rigidly connected to the specimen carrier. A bearing assembly disposed outside the region of the specimen carrier is also provided and includes a pivot bearing for receiving the end portion of the first positioning lever in force-locking engagement therein. The pivot bearing has a center of rotation about which the first positioning lever is pivotable. A displaceable mount accommodates the bearing and the second positioning lever engages the mount for adjusting the displacement of the center of rotation with respect to the particle beam.
US Patent References:
Corpuscular radiation apparatus
Riecke - April 1963 - 3086112
Specimen holding device with means to tilt, rotate and shift the specimen
Watanabe et al. - March 1966 - 3240934
ELECTRON MICROSCOPE SPECIMEN STAGE WHICH MAINTAINS SPECIMEN POSITION WHEN SUBJECTED TO THERMAL FLUCTUATIONS
Suzuki - October 1911 - 3612863
ADJUSTING DEVICE FOR CORPUSCULAR-BEAM APPARATUS
Heide - December 1971 - 3628013
Corpuscular radiation apparatus
Riecke - April 1963 - 3086112
Specimen holding device with means to tilt, rotate and shift the specimen
Watanabe et al. - March 1966 - 3240934
ELECTRON MICROSCOPE SPECIMEN STAGE WHICH MAINTAINS SPECIMEN POSITION WHEN SUBJECTED TO THERMAL FLUCTUATIONS
Suzuki - October 1911 - 3612863
ADJUSTING DEVICE FOR CORPUSCULAR-BEAM APPARATUS
Heide - December 1971 - 3628013
Application Number:
05/383712
Publication Date:
07/09/1974
Filing Date:
07/30/1973
View Patent Images:
Export Citation:
Assignee:
Siemens Aktiengesellschaft (Munich, DT)
Primary Class:
Other Classes:
250/311
International Classes:
H01J37/20; H01J37/20
Field of Search:
250/311,442,491,456,440
Primary Examiner:
Lawrence, James W.
Assistant Examiner:
Anderson B. C.
Attorney, Agent or Firm:
Kenyon & Keynon Reilly Carr & Chapin
Parent Case Data:
This is a continuation of application Ser. No. 275,561 filed July 27, 1972, now abandoned.
Claims:
What is claimed is
1. In a particle-beam apparatus such as an electron microscope having a housing containing a beam generator for generating a particle beam, and a specimen carrier for receiving a specimen to be investigated in the apparatus, the specimen carrier being penetrable by the beam and being displaceable within the housing transversely to the beam, and an adjusting mechanism for effecting the traverse displacement of the specimen carrier, said adjusting mechanism comprising first and second pivotally mounted positioning levers having respective end portions facing the specimen carrier and movable in mutually perpendicular directions, said first positioning lever being rigidly connected to the specimen carrier; and a bearing assembly disposed outside the region of the specimen carrier and comprising a pivot bearing for receiving the end portion of said first positioning lever in force-locking engagement therein, said pivot bearing having a center of rotation through which axes transverse and parallel to the particle beam pass, said first positioning lever being pivotable about said axes, and displaceable mounting means for accommodating said bearing and for shifting said center of rotation with respect to the particle-beam, comprising a carriage slideably mounted inside the housing of the apparatus, said pivot bearing being securely mounted on said carriage, and said end portion of said second positioning lever engaging said carriage for adjusting the displacement thereof with respect to the particle beam, said second positioning lever engaging said mounting means for adjusting the displacement of said mounting means for adjusting the displacement of said center of rotation with respect to the particle beam; and spring pressure means for spring loading said first positioning lever for holding the same in force-locking engagement with said pivot bearing.
2. The adjusting mechanism of claim 1, said end portion of said first positioning lever being in engagement with said pivot bearing, said first positioning lever being an elongated member having rotational symmetry about its longitudinal axis and being seated in said pivot bearing so as to be tiltable about an axis passing through said center of rotation.
3. The adjusting mechanism of claim 2, said first positioning member being rotatably held so as to be rotatable about said longitudinal axis.
4. In a particle-beam apparatus such as an electron microscope having a housing containing a beam generator for generating a particle beam, and a specimen carrier for receiving a specimen to be investigated in the apparatus, the specimen carrier being penetrable by the beam and being displaceable within the housing transversely to the beam, and an adjusting mechanism for effecting the transverse displacement of the specimen carrier, said adjusting mechanism comprising first and second pivotally mounted positioning levers having respective end portions movable in mutually perpendicular directions, the end portion of said first positioning lever being apportioned into two subsidiary portions, said first positioning lever being rigidly connected to the specimen carrier at one of said subsidiary portions; and a bearing assembly disposed outside the region of the specimen carrier and comprising a pivot bearing for receiving said first positioning lever in force-locking engagement therein at the other one of said two subsidiary portions, said pivot bearing having a center of rotation through which axes transverse and parallel to the particle beam pass, said first positioning lever being pivotable about said axes, and displaceable mounting means for accommodating said bearing and for shifting said center of rotation with respect to the particle beam, comprising a carriage slideably mounted inside the housing of the apparatus, said pivot bearing being securely mounted on said carriage, and said end portion of said second positioning lever engaging said carriage for adjusting the displacement thereof with respect to the particle beam, said second positioning lever engaging said mounting means for adjusting the displacement of said center of rotation with respect to the particle beam; and spring pressure means for spring loading said first positioning lever for holding the same in force-locking engagement with said pivot bearing.
1. In a particle-beam apparatus such as an electron microscope having a housing containing a beam generator for generating a particle beam, and a specimen carrier for receiving a specimen to be investigated in the apparatus, the specimen carrier being penetrable by the beam and being displaceable within the housing transversely to the beam, and an adjusting mechanism for effecting the traverse displacement of the specimen carrier, said adjusting mechanism comprising first and second pivotally mounted positioning levers having respective end portions facing the specimen carrier and movable in mutually perpendicular directions, said first positioning lever being rigidly connected to the specimen carrier; and a bearing assembly disposed outside the region of the specimen carrier and comprising a pivot bearing for receiving the end portion of said first positioning lever in force-locking engagement therein, said pivot bearing having a center of rotation through which axes transverse and parallel to the particle beam pass, said first positioning lever being pivotable about said axes, and displaceable mounting means for accommodating said bearing and for shifting said center of rotation with respect to the particle-beam, comprising a carriage slideably mounted inside the housing of the apparatus, said pivot bearing being securely mounted on said carriage, and said end portion of said second positioning lever engaging said carriage for adjusting the displacement thereof with respect to the particle beam, said second positioning lever engaging said mounting means for adjusting the displacement of said mounting means for adjusting the displacement of said center of rotation with respect to the particle beam; and spring pressure means for spring loading said first positioning lever for holding the same in force-locking engagement with said pivot bearing.
2. The adjusting mechanism of claim 1, said end portion of said first positioning lever being in engagement with said pivot bearing, said first positioning lever being an elongated member having rotational symmetry about its longitudinal axis and being seated in said pivot bearing so as to be tiltable about an axis passing through said center of rotation.
3. The adjusting mechanism of claim 2, said first positioning member being rotatably held so as to be rotatable about said longitudinal axis.
4. In a particle-beam apparatus such as an electron microscope having a housing containing a beam generator for generating a particle beam, and a specimen carrier for receiving a specimen to be investigated in the apparatus, the specimen carrier being penetrable by the beam and being displaceable within the housing transversely to the beam, and an adjusting mechanism for effecting the transverse displacement of the specimen carrier, said adjusting mechanism comprising first and second pivotally mounted positioning levers having respective end portions movable in mutually perpendicular directions, the end portion of said first positioning lever being apportioned into two subsidiary portions, said first positioning lever being rigidly connected to the specimen carrier at one of said subsidiary portions; and a bearing assembly disposed outside the region of the specimen carrier and comprising a pivot bearing for receiving said first positioning lever in force-locking engagement therein at the other one of said two subsidiary portions, said pivot bearing having a center of rotation through which axes transverse and parallel to the particle beam pass, said first positioning lever being pivotable about said axes, and displaceable mounting means for accommodating said bearing and for shifting said center of rotation with respect to the particle beam, comprising a carriage slideably mounted inside the housing of the apparatus, said pivot bearing being securely mounted on said carriage, and said end portion of said second positioning lever engaging said carriage for adjusting the displacement thereof with respect to the particle beam, said second positioning lever engaging said mounting means for adjusting the displacement of said center of rotation with respect to the particle beam; and spring pressure means for spring loading said first positioning lever for holding the same in force-locking engagement with said pivot bearing.
Description:
BACKGROUND OF THE INVENTION
The invention relates to a particle-beam apparatus such as an electron microscope or the like having a movable specimen carrier for receiving specimens to be investigated. The particle-beam apparatus is equipped with an adjusting mechanism for displacing the specimen carrier transversely with respect to the beam.
It is known to heat or cool specimens that have been placed in the evacuated interior space of particle-beam apparatus such as electron microscopes. The specimens are held in specimen carriers displaceable transversely with respect to the beam. Because of the unavoidable heat transfer between the specimens and their carrier on the one hand, and the mechanical positioning devices acting on the specimen carrier on the other hand, a heat flow occurs which causes changes in the length of the positioning device. These length changes are detrimental, particularly in high-resolution investigations, because the specimen drifts out of the path of the electron beam.
It is known from Deutsche Offenlegungsschrift 1,959,424 to provide a holder for carrying the specimen which can pivot about a center of rotation which is fixed with respect to the apparatus and can be moved longitudinally relative to the wall of the housing. The mount forms the positioning member for a direction transverse to the axis of the particle beam. A second positioning lever engages the mount for a second positioning direction which is also transverse to the direction of the particle beam and is furthermore, perpendicular to the positioning direction of the holder. The point of application of the second positioning lever is located on a line of action passing through the center of the specimen. The center of rotation is fixed with respect to the housing and is also located on this line of action. This known construction results in a stable position of the specimen also when the positioning device is heated or cooled. A disadvantage of this arrangement is that only little space is available for accommodating the specimen carrier on the holder.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a particle-beam apparatus such as an electron microscope or the like wherein the adjusted position of the specimen remains essentially stable with respect to the particle beam in the presence of temperature changes.
It is another object of the invention to provide a particle beam apparatus having means for positioning the specimen carrier which affords space for larger specimen carriers as well as for facilitating the insertion and removal of specimens.
It is still another object of the invention to provide an adjusting mechanism for the specimen carrier of a particle-beam apparatus which affords considerable flexibility in positioning the specimen with respect to the particle beam.
The invention concerns a particle-beam apparatus such as an electron microscope or the like wherein a specimen carrier is provided to receive specimens to be investigated. The specimen carrier can be penetrated by the particle beam and is displaceable transversely with respect to the beam within the apparatus housing. An adjusting mechanism effects the transverse displacement of the specimen carrier.
According to a feature of the invention, the adjusting mechanism has two pivotally mounted positioning levers which effect the displacement of the specimen carrier. The levers have respective end portions that face the specimen carrier and that are movable in mutually perpendicular directions. The first one of the two levers is rigidly connected to the specimen carrier. The pivot bearing of a bearing assembly disposed outside the specimen carrier receives the end portion of the first lever in force-locking engagement therein and has a center of rotation about which the first lever is pivotable.
The bearing assembly also has a displaceable mount for accommodating the pivot bearing and for shifting the center of rotation with respect to the particle beam. The second lever engages the mount for adjusting the displacement of the center of rotation with respect to the particle beam.
By moving the center of rotation away from the region of the specimen carrier, the adjusting mechanism according to the invention makes it possible to use larger specimen carriers. The specimens can be inserted and removed more easily and, if desired can also be made larger. Although the specimen carrier is outside the region of the pivot bearing and its center of rotation, it is nonetheless preferably near the pivot bearing. Thus, the end portion of the first positioning lever can be viewed as being apportioned into two subsidiary portions with the first positioning lever rigidly connected to the specimen carrier at one of the subsidiary portions. The pivot bearing then receives the first positioning lever in force-locking engagement therein at the other one of said two subsidiary portions.
The pivot bearing assembly establishes the condition for supporting the specimen carrier with a tumbling motion. According to still another feature and in a preferred embodiment of the invention, the first positioning lever is configured so as to be rotationally symmetrical with respect to its longitudinal axis; this permits displacement in a first direction transverse to the direction of the beam, as well as in a second direction, parallel to the direction of the beam, that is along the Z-axis of the apparatus. Thus the first lever is seated in the pivot bearing so as to be tiltable about respective axes passing through the center of rotation. According to a further feature the first lever can be rotated about its longitudinal axis, whereby the specimen is tilted with respect to the beam, pivot bearing is preferably attached to a slide which is movably guided in the apparatus housing and is actuated by the free end portion of the second positioning lever, that is, the end portion thereof facing the specimen carrier.
Although the invention is illustrated and described herein as a particle-beam apparatus such as an electron microscope or the like, it is nevertheless not intended to be limited to the details shown since various modifications may be made therein within the scope and the range of the claims. The invention, however, together with additional objects and advantages will be best understood from the following description and in connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
The drawing illustrates a cross-section taken through the housing column of an electron microscope. The section is taken at the elevation of the specimen carrier and illustrates the positioning mechanism according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawing, the housing 1 of the electron microscope accommodates in its interior 2 the electromagnetic objective lens 3 having a central pole piece bore 4. The electron beam of the electron microscope passes through the bore 4. A specimen carrier 5 is brought into the area of the bore 4. The carrier 5 receives specimens 6 which are to be investigated. The specimen carrier 5 can be moved transversely within the apparatus housing 1. The displacement is effected by means of two pivotally borne levers 7, 8 having respective end portions 9 and 10 facing the specimen carrier 5. The ends can be displaced in mutually perpendicular directions to displace the specimen carrier 5. By means of a pivot bearing part 11, arranged outside of the area of the specimen carrier, the lever 7 engages a pivot bearing 12 in a force-locking manner. The center of rotation 13 of the bearing 12 can be moved relatively to the particle-beam and can be adjusted in position by the second positioning lever 8. The center of rotation 13 of the pivot bearing 12 constitutes at the same time the pivot point for the positioning lever 7. For the illustrated embodiment, the positioning lever 7 is configured so as to be rotationally symmetrical and is therefore supported in the pivot bearing 12 so that it can carry out a tumbling motion. For example, the lever 7 can be tilted laterally about an axis passing through the center of rotation 13. The pivot bearing 12 and the pivot bearing part 11 are configured so that the positioning lever 7 is in addition supported so as to be rotatable about its longitudinal axis 14. This makes it possible to tilt the specimen 6 relative to the particle beam.
The pivot bearing part 12 is attached to a slide 15 which is movably guided in the apparatus housing 1 by means of a slide bearing 16. The slide 15 is actuated by the free end 10 of the positioning lever 8. The positioning lever 8 can pivot about the pivot bearing 17, which is fixed relative to the apparatus. The end 18 of lever 8 extends through the housing 1 of the electron microscope whereat the lever is driven by a spindle 19 which functions together with a counter-spring arrangement 20.
The positioning lever 7 is actuated via a second spindle 21 which is accessible outside of the apparatus housing 1 and cooperates with a counter-spring arrangement 22. The specimen is tilted, if the positioning lever 7 is rotated about its longitudinal axis 14 in the direction of the arrow 23. The counter-spring arrangement 22 can be rotated by means of a ball bearing arrangement 25 which is attached on the outside of the housing 1. If the part 24 is rotated 90° relative to the position shown in the drawing, operating spindle 21 results in a displacement of the specimen 6 along the Z-axis of the apparatus, that is, in the direction of the particle beam.
To obtain the force coupling between the pivot bearing part 11 and the pivot bearing 12, the positioning lever 7 is loaded with spring pressure means in the form of a spring 26 which urges the positioning lever 7 into the interior 2 of the housing 1 and into force-locking engagement with bearing 12.
With the invention a particle-beam apparatus such as an electron microscope is provided wherein the adjusted portion of the specimen under investigation and through which the particle beam passes, remains essentially stable with respect to the particle beam also in the presence of temperature changes.
The invention relates to a particle-beam apparatus such as an electron microscope or the like having a movable specimen carrier for receiving specimens to be investigated. The particle-beam apparatus is equipped with an adjusting mechanism for displacing the specimen carrier transversely with respect to the beam.
It is known to heat or cool specimens that have been placed in the evacuated interior space of particle-beam apparatus such as electron microscopes. The specimens are held in specimen carriers displaceable transversely with respect to the beam. Because of the unavoidable heat transfer between the specimens and their carrier on the one hand, and the mechanical positioning devices acting on the specimen carrier on the other hand, a heat flow occurs which causes changes in the length of the positioning device. These length changes are detrimental, particularly in high-resolution investigations, because the specimen drifts out of the path of the electron beam.
It is known from Deutsche Offenlegungsschrift 1,959,424 to provide a holder for carrying the specimen which can pivot about a center of rotation which is fixed with respect to the apparatus and can be moved longitudinally relative to the wall of the housing. The mount forms the positioning member for a direction transverse to the axis of the particle beam. A second positioning lever engages the mount for a second positioning direction which is also transverse to the direction of the particle beam and is furthermore, perpendicular to the positioning direction of the holder. The point of application of the second positioning lever is located on a line of action passing through the center of the specimen. The center of rotation is fixed with respect to the housing and is also located on this line of action. This known construction results in a stable position of the specimen also when the positioning device is heated or cooled. A disadvantage of this arrangement is that only little space is available for accommodating the specimen carrier on the holder.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a particle-beam apparatus such as an electron microscope or the like wherein the adjusted position of the specimen remains essentially stable with respect to the particle beam in the presence of temperature changes.
It is another object of the invention to provide a particle beam apparatus having means for positioning the specimen carrier which affords space for larger specimen carriers as well as for facilitating the insertion and removal of specimens.
It is still another object of the invention to provide an adjusting mechanism for the specimen carrier of a particle-beam apparatus which affords considerable flexibility in positioning the specimen with respect to the particle beam.
The invention concerns a particle-beam apparatus such as an electron microscope or the like wherein a specimen carrier is provided to receive specimens to be investigated. The specimen carrier can be penetrated by the particle beam and is displaceable transversely with respect to the beam within the apparatus housing. An adjusting mechanism effects the transverse displacement of the specimen carrier.
According to a feature of the invention, the adjusting mechanism has two pivotally mounted positioning levers which effect the displacement of the specimen carrier. The levers have respective end portions that face the specimen carrier and that are movable in mutually perpendicular directions. The first one of the two levers is rigidly connected to the specimen carrier. The pivot bearing of a bearing assembly disposed outside the specimen carrier receives the end portion of the first lever in force-locking engagement therein and has a center of rotation about which the first lever is pivotable.
The bearing assembly also has a displaceable mount for accommodating the pivot bearing and for shifting the center of rotation with respect to the particle beam. The second lever engages the mount for adjusting the displacement of the center of rotation with respect to the particle beam.
By moving the center of rotation away from the region of the specimen carrier, the adjusting mechanism according to the invention makes it possible to use larger specimen carriers. The specimens can be inserted and removed more easily and, if desired can also be made larger. Although the specimen carrier is outside the region of the pivot bearing and its center of rotation, it is nonetheless preferably near the pivot bearing. Thus, the end portion of the first positioning lever can be viewed as being apportioned into two subsidiary portions with the first positioning lever rigidly connected to the specimen carrier at one of the subsidiary portions. The pivot bearing then receives the first positioning lever in force-locking engagement therein at the other one of said two subsidiary portions.
The pivot bearing assembly establishes the condition for supporting the specimen carrier with a tumbling motion. According to still another feature and in a preferred embodiment of the invention, the first positioning lever is configured so as to be rotationally symmetrical with respect to its longitudinal axis; this permits displacement in a first direction transverse to the direction of the beam, as well as in a second direction, parallel to the direction of the beam, that is along the Z-axis of the apparatus. Thus the first lever is seated in the pivot bearing so as to be tiltable about respective axes passing through the center of rotation. According to a further feature the first lever can be rotated about its longitudinal axis, whereby the specimen is tilted with respect to the beam, pivot bearing is preferably attached to a slide which is movably guided in the apparatus housing and is actuated by the free end portion of the second positioning lever, that is, the end portion thereof facing the specimen carrier.
Although the invention is illustrated and described herein as a particle-beam apparatus such as an electron microscope or the like, it is nevertheless not intended to be limited to the details shown since various modifications may be made therein within the scope and the range of the claims. The invention, however, together with additional objects and advantages will be best understood from the following description and in connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
The drawing illustrates a cross-section taken through the housing column of an electron microscope. The section is taken at the elevation of the specimen carrier and illustrates the positioning mechanism according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawing, the housing 1 of the electron microscope accommodates in its interior 2 the electromagnetic objective lens 3 having a central pole piece bore 4. The electron beam of the electron microscope passes through the bore 4. A specimen carrier 5 is brought into the area of the bore 4. The carrier 5 receives specimens 6 which are to be investigated. The specimen carrier 5 can be moved transversely within the apparatus housing 1. The displacement is effected by means of two pivotally borne levers 7, 8 having respective end portions 9 and 10 facing the specimen carrier 5. The ends can be displaced in mutually perpendicular directions to displace the specimen carrier 5. By means of a pivot bearing part 11, arranged outside of the area of the specimen carrier, the lever 7 engages a pivot bearing 12 in a force-locking manner. The center of rotation 13 of the bearing 12 can be moved relatively to the particle-beam and can be adjusted in position by the second positioning lever 8. The center of rotation 13 of the pivot bearing 12 constitutes at the same time the pivot point for the positioning lever 7. For the illustrated embodiment, the positioning lever 7 is configured so as to be rotationally symmetrical and is therefore supported in the pivot bearing 12 so that it can carry out a tumbling motion. For example, the lever 7 can be tilted laterally about an axis passing through the center of rotation 13. The pivot bearing 12 and the pivot bearing part 11 are configured so that the positioning lever 7 is in addition supported so as to be rotatable about its longitudinal axis 14. This makes it possible to tilt the specimen 6 relative to the particle beam.
The pivot bearing part 12 is attached to a slide 15 which is movably guided in the apparatus housing 1 by means of a slide bearing 16. The slide 15 is actuated by the free end 10 of the positioning lever 8. The positioning lever 8 can pivot about the pivot bearing 17, which is fixed relative to the apparatus. The end 18 of lever 8 extends through the housing 1 of the electron microscope whereat the lever is driven by a spindle 19 which functions together with a counter-spring arrangement 20.
The positioning lever 7 is actuated via a second spindle 21 which is accessible outside of the apparatus housing 1 and cooperates with a counter-spring arrangement 22. The specimen is tilted, if the positioning lever 7 is rotated about its longitudinal axis 14 in the direction of the arrow 23. The counter-spring arrangement 22 can be rotated by means of a ball bearing arrangement 25 which is attached on the outside of the housing 1. If the part 24 is rotated 90° relative to the position shown in the drawing, operating spindle 21 results in a displacement of the specimen 6 along the Z-axis of the apparatus, that is, in the direction of the particle beam.
To obtain the force coupling between the pivot bearing part 11 and the pivot bearing 12, the positioning lever 7 is loaded with spring pressure means in the form of a spring 26 which urges the positioning lever 7 into the interior 2 of the housing 1 and into force-locking engagement with bearing 12.
With the invention a particle-beam apparatus such as an electron microscope is provided wherein the adjusted portion of the specimen under investigation and through which the particle beam passes, remains essentially stable with respect to the particle beam also in the presence of temperature changes.