The present invention relates to an imaging device for optical-microscopic imaging of an object, particularly an optical microscope having an adjustable objective, and a method for optical microscopy.
In optical microscopy, it is typically necessary to set the position of an object (sample) in relation to the microscope and particularly in relation to the objective of the microscope and possibly change the position in a predetermined way during the microscopic imaging or observation or between different imaging or observation steps. The mutual arrangement (relative position) must be adjustable in all three spatial directions. For some applications, there is the additional requirement of variation of the observation angle, i.e., the angle between the optical axis of the objective and the surface normal of the object, for example.
Until now, it has been typical to use an adjustable table having a drive for all three spatial directions to adjust the relative position. The object is situated on the adjustable table and positioned in relation to the fixed microscope. For many applications, however, it is undesirable or even impossible to move the object in relation to the microscope. Examples of this are the observation of heavy objects or objects which are immovable for another reason or the combination of microscopic imaging with other measurement or manipulation methods, such as the derivation of electrical potentials in neurophysiology.
The relative positioning of an object and the microscope is also possible through movement of the entire microscope construction for a fixed object. However, this method is restricted to a few special applications for the following reasons. Firstly, microscopes typically have a high weight, so that not every alignment in space is achievable without something further. Furthermore, there is frequently the necessity to align the microscope in relation to further stationary devices, such as lasers. For the reasons cited, until now, complex microscopic methods in particular, such as confocal or multiquanta microscopy, have been executable not at all or in only a limited way on fixed or stationary objects.
Microscopes are known in which the objective is displaced in relation to the remaining construction of the microscope for focusing, i.e., to set the objective on a focal plane in the object. This focusing movement along the optical axis of the objective is based on the following feature of most modern microscopes. Specifically, a microscope objective is typically laid out for an infinite image distance. This means that the imaged region of the object is imaged at infinity. An intermediate image of the object which may be observed using an ocular is generated using a tube lens. An advantage of this construction is particularly that the distance between the objective and the tube lens may be varied within specific limits for focusing without the imaging properties of the entire optical system, which are limited by the diffraction, being impaired. The conventional focusing movement of the objective is restricted to axial displacements, however. Free setting of the relative position between object and microscope in all spatial directions is therefore not possible.
The object of the present invention is to provide an improved imaging device for microscopic imaging of an object, using which the disadvantages of conventional microscopes are overcome and which particularly allows free setting of the relative coordinates between the objective and object without restriction of the imaging properties of the imaging device. It is also the object of the present invention to provide an improved imaging method for optical microscopy, using which free selection of the object region imaged is possible on stationary objects.
These objects are solved by an imaging device, a microscope, and a method having the features according to claims 1, 11, and 12. Advantageous embodiments and applications of the present invention result from the dependent claims.
The basic idea of the invention is to refine an imaging device for microscopic imaging of an object having an objective and a tube optic in such a way that the objective is positioned so it is movable in relation to the tube optic in at least one direction which deviates from the direction of the optical axis of the objective, and a deflection device for perpendicular and axially centered alignment of the beam path from the objective to the tube optic and an adjustment device for positioning the objective and for setting the deflection device are provided. The deflection and adjustment devices are operated in such a way that the optical axis of the objective and the optical axis of the tube optic deflected using the deflection device are coincident. Using an objective which is set up to generate the object image in infinity, this imaging device has the advantage that the objective may execute movements in relation to the tube optic and therefore in relation to the stationary microscope construction without the generation of an intermediate image being impaired. In particular, it is possible to execute translational and/or pivot movements using the objective. The mobility of the objective means that the position of the objective and/or the alignment of its optical axis is changeable between different operating states and may be set fixed in each new state.
Using the deflection device, which has at least one adjustable reflector according to the present invention, and the adjustment device, displacements of the beam path from the objective to the tube optic are compensated for in such a way that the beam path with the object image imaged at infinity is thus always incident on the tube optic in the same way as is the case for conventional microscopes having axially aligned optics. The translational movement means that the objective is movable according to the two spatial directions perpendicularly to the optical axis. The pivot movement means that the objective is pivotable around an axis which is perpendicular to the optical axis of the objective. Therefore, any arbitrary positions and observation angles may be assumed in relation to the object. This allows manifold microscopic images, particularly on fixed or stationary objects.
According to a first embodiment of the present invention, the deflection device is equipped with an adjustable reflector which is displaceable along the optical axis of the tube optic. In this case, the adjustment device contains an X drive, using which the objective and the reflector are displaceable jointly along the optical axis of the tube optic. Using this embodiment, an especially simple construction of the deflection device having only one reflector and only one translational drive device is advantageously implemented. If the objective with the reflector is displaced in the direction of the optical axis of the tube optic, the objective may be moved over the object. This procedure is performed primarily in a fixed direction, which is already sufficient for numerous applications, particularly in materials testing. During the movement of the objective with the reflector, worsening of the imaging is advantageously avoided in spite of the change of the distance between objective and barrel object.
According to a further preferred embodiment of the present invention, the deflection device includes two reflectors, specifically an objective reflector and a tube reflector, the adjustment device having a Y drive, using which the objective and the objective reflector are displaceable jointly along a reference direction perpendicular to the optical axis of the tube optic. This design has the advantage over the first embodiment that, particularly when combined with the X drive cited, translations of the objective in both orthogonal directions perpendicular to the optical axis of the objective are made possible. Therefore, the movement range of the objective over the object is expanded. Complete surfaces of the object are accessible to microscopic imaging.
The adjustment device is advantageously equipped with a translational Z drive, using which the objective is displaceable along its optical axis and settable at a specific position. This allows the focusing of the optical system of the imaging device according to the present invention on the particular desired focal plane in the object, which is of special advantage for confocal microscopy in particular.
According to a further preferred embodiment of the present invention, the deflection device is additionally equipped with an intermediate reflector, the objective and intermediate reflectors being displaceable and settable together in such a way that if the tube reflector and/or the objective reflector are displaced with the objective, the length of the beam path from the objective to the tube optic remains constant. Through this measure, the displacement of the image of the objective exit pupil, e.g., on the scanning mirror, may advantageously be completely avoided.
According to further embodiments of the present invention, the objective may be pivoted with the objective reflector around at least one axis perpendicular to the optical axis of the objective. The objective is pivoted using at least one pivot drive. This advantageously allows setting of predetermined observation angles from the objective in relation to the object or focal planes in the object which are defined in an aligned way.
Basically, the translational drives and the pivot drive may be actuated and adjusted independently from one another. However, synchronized operation of all drives is preferred according to the present invention. For synchronized operation, all components which are adjusted in a specific direction are moved simultaneously and using a shared drive.
A subject of the present invention is also a microscope which is equipped with the imaging device described, and an imaging method using the imaging device described, in which the objective is subjected to translational and/or pivot movements and a compensation of the changes of the beam path to the tube optic arising in this case is performed using the deflection device and the adjustment device.
The present invention has the following advantages. The imaging device according to the present invention is usable in all microscope types or microscopy methods which are known per se. There are no restrictions in regard to the type of samples to be investigated, the optical parameters of the imaging system, the type of image recording, or the like. The imaging device according to the present invention allows movement of the objective over a large travel and/or pivot range. The movement may surprisingly be performed without tilting movements, which would interfere with the focusing. Firstly, this allows relatively large, fixed objects (characteristic dimensions in the cm range) to be investigated. Secondly, through the mobility of the objective, a working space may be provided in order to possibly subject the object to additional investigations or processing. During a translational movement of the objective in a plane perpendicular to the optical axis of the objective, the focusing advantageously remains constant. The object may be imaged and/or processed in a focal plane which remains uniform. The deflection device used according to the present invention has a large variability. If multiple reflectors are provided, different folds of the beam path from the objective to the tube optic may be provided, whose geometry is tailored without anything further to the particular given conditions on the measurement construction.
Further advantages and characteristics of the present invention result from the description of the attached figures.
The imaging device according to the present invention is preferably provided for optical-microscopic imaging of an object and therefore for use in or with a microscope. There are no restrictions in regard to combination with specific microscope construction types. In the following, the design of the beam path between the objective and the tube optic of an imaging device according to the present invention is therefore primarily discussed. It is further to be noted that the implementation of the present invention is not restricted to the embodiments explained in the following, having up to three reflectors in the beam path of a deflection device used according to the present invention. For specific applications, further folds of the beam path in further spatial directions and/or using further reflectors may be provided. Furthermore, notwithstanding the schematic illustrations, the lengths of the sections of the beam path may be in different ratios in the concrete implementation of the present invention.
An important basic principle of the present invention is that the objective of the imaging device is arranged so it is movable in relation to the tube optic in at least one direction deviating from the direction of the optical axis of the objective. The beam path from the objective to the tube optic runs via at least one reflector of a deflection device. The objective with at least one reflector is moved along the optical axis always in a section of the beam path during translational movements.
The different movement possibilities of the imaging device according to the present invention are illustrated in
Generally, the beam path from the objective to the tube optic is deflected at least one time using at least one reflector. At least two sections are formed. The deflection occurs at each reflector by a fixed angle, e.g., 90°. All sections of the beam path run along one of the X, Y, or Z directions to implement translational movements. For pivot movements, the coordinate system is additionally pivotable around the X and/or Y axes.
The reflectors are plane reflectors. They preferably include plane mirrors. For example, dielectric multilayer mirrors of the type LSBM-NIR (available from LINOS photonics) are used. Alternatively, prism reflectors may also be provided as the reflectors. Each reflector is aligned in each case in such a way that the surface normals of the mirror surface form an angle of 45°, for example, to the neighboring sections of the beam path. This alignment is fixed if only translational movements of the objective are provided. For pivot movements of the objective, pivotability of single reflectors is additionally provided.
The imaging device 10 according to the present invention shown in
Any microscope objective known per se, whose optical parameters are tailored to the particular imaging, measurement, or processing task, may be used as the objective 21. The objective 21 images an image from the object into infinity.
A parallel beam path is generated which is directed onto the tube optic 22 via the reflector 31. The tube optic 22 is used for generating an intermediate image of the object and generating an image of the entrance pupil of the objective 21. Depending on the microscope type, the intermediate image generated by the tube optic 22 is visually observed and/or detected using a detector (e.g., CCD detector), or a scanner mirror (scanning mirror, oscillating mirror) for scanning microscopy is located at the point of imaging of the entrance pupil of the objective 21. The tube optic 22 may be formed, as in a conventional microscope, by a tube lens or alternatively by a construction made of multiple lenses. The tube optic 22 is, for example, of the type Nikon MXA22018. Generally, the parts of the imaging optic 20 may also be formed by mirror optics instead of lens optics.
Using the reflector 31, the parallel beam path from the objective 21 to the tube optic 22 is divided into two sections 23, 24. In
The objective 21 is aligned vertically in the Z direction. Correspondingly, the first section 23 of the beam path runs vertically in the Z direction from the objective 21 to the reflector 31. The reflector 31 is positioned slanted by 45° toward the X direction in relation to the Z direction, so that the second section 24 runs toward the tube optic 22 along its optical axis in the X direction.
In the embodiment shown, the adjustment device 40 includes an X drive 41 and a Z drive 43. According to the present invention, these drives work together with the deflection device 30 in the way described in the following.
The objective 21 is situated so it is movable in a direction deviating from its optical axis. In the embodiment shown in
For microscopic imaging of an object, the objective 21 is focused on the focal plane of interest of the object. In order to image different regions of the object, the objective 21 may be moved together with the reflector 31 in the X direction, without the optical imaging with the tube lens 22 being restricted.
An expansion to two translational directions, specifically the X and Y directions, is illustrated in
The deflection and adjustment devices used according to the present invention work together as follows to generate translational movements of the objective 21 in the X and/or Y directions. In the following explanation, reference is also made to the table specified below, in which the degrees of freedom of the individual components of the imaging device according to the present invention are listed. To set the beam path on the tube optic 22 in the event of a X translation of the objective 21, the tube reflector 33 is displaceable in the X direction. No adjustability of the tube reflector 33 is provided in the Y and Z direction, in order to maintain the alignment to the fixed tube optic 22. The adjustment of the tube reflector 32 is performed analogously to the adjustment of the reflector 31 in
To set the beam path on the tube reflector 33 and therefore on the tube optic 22 in the event of translation of the objective 21 in the Y direction, the objective reflector 33 is displaceable in the Y direction. This displacement along the optical axis of the beam path in section 24 is performed analogously to the above displacements in the X direction. The components shown in
Through joint displacement of the objective 21 with the objective reflector 32 and the tube reflector 33 by equal path lengths in the X direction, the objective 21 is correspondingly moved over the object in the X direction while maintaining the optical imaging. The translation in the Y direction results through joint displacement of the objective 21 and the objective reflector 32 by equal path lengths in the Y direction. The movement path in the X and Y directions is up to 25 mm in each case, for example.
In the embodiments shown in
The deflection device used according to the present invention includes three reflectors as shown in
The reflectors 34 through 36 cover a beam path folded analogously to the principles explained above, having four sections 23 through 26. According to the functional principle and the overview illustration in the table (see below), the objective 21 has degrees of freedom in all spatial directions. The objective reflector 34 is also adjustable in all three spatial directions. The intermediate reflector 35 is adjustable in the X and Z directions, while the tube reflector 36 only has a degree of freedom in the X direction. For translation of the objective 21 in the X direction, all components 21, 34, 35, and 36 are moved in the X direction by equal path lengths. This is preferably performed using a shared X drive (not shown). For translation in the Y direction, the components 21 and 34 are correspondingly moved by equal path lengths, which is again preferably performed using a shared Y drive. In the event of X and/or Y translations, the lengths of the sections 24 and 26 are accordingly changed. In order to compensate for these changes and keep the total length of the beam path constant, adjustment of the reflectors 34 and 35 in the Z direction is provided. For this purpose, the adjustment device has a Z drive having a first partial drive for focusing of the objective 21 and a second partial drive for shared compensational movement of the reflectors 34 and 35. The second partial drive is controlled in such a way that in the event of translation in the X or Y direction by a specific path length, a displacement of the reflectors 34 and 35 in the Z direction corresponding to half of the path length occurs. Since this compensational movement has a doubled effect on the two sections 23 and 25, the corresponding translation is compensated for.
The length compensations are each performed correspondingly in the X direction or in the Z direction as shown in
The optical axis of the initially unpivoted objective 21 is aligned vertically in the Z direction. The focal plane is parallel to the X-Y plane. In order to tilt the focal plane in relation to the X-Y plane, the objective 21 is pivoted with the objective reflector 32. The pivot axis is coincident with the optical axis of the imaging optic 22 along the section 25 (
In
For synchronized translation and/or pivoting, using the X drive 41, besides the optical parts, the Y and Z drives 42, 43 are also actuated and the Z drive 43 is also actuated using the Y drive 42. For pivoting, the X drive 41 is attached to the YZ pivot drive 44, and this drive is attached to the XZ pivot drive 45 (or vice versa). The X, Y, and Z drives are preferably linear actuating drives, such as typical linear actuator tables. For example, linear actuator tables of the type micromanipulator MP285 (3Z version, Sutter Instruments) are used. The schematically illustrated YZ and XZ pivot drives 44, 45 are formed by rotary tables, for example, to which the X drive is attached via a support tube.
In the embodiment shown in
In
A microscope 60 according to the present invention, which is equipped with the imaging device described above, is illustrated in
The microscope 60 may furthermore be equipped with additional devices, such as a calibration laser or measurement devices. Using the calibration laser, the imaging device according to the present invention is recalibrated if necessary before beginning operation or after adjustment steps, for example.
The features of the present invention disclosed in the preceding description, the claims, and the figures may be significant in their various designs both alone and in any combination for the implementation of the present invention.
Number | Date | Country | Kind |
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101 52 609.1 | Oct 2001 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP02/11937 | 10/25/2002 | WO |