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  Correction device for an optical arrangement and confocal microscope with such a deviceCorrection device for an optical arrangement and confocal microscope with such a device description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070253044, Correction device for an optical arrangement and confocal microscope with such a device. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This application is a continuation application of U.S. Ser. No. 10/967,347 filed Oct. 19, 2004 which is incorporated in its entirety by reference herein. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The invention refers to a correction device for an optical arrangement that exhibits a light path, for example for a microscope. It specially refers to a confocal microscope with such a correction device. [0004] 2. Related Art [0005] Optical arrangements, like for example microscopes, confocal microscopes or laser scanning microscopes regularly exhibit adjustable elements, in order to adjust different operating conditions. Thus it is well known for example, to exchange filters or color splitters, in order to be able to work with different lighting wavelengths or to evaluate different fluorescence radiation in different wavelength ranges. The adjustment or change mechanisms must be implemented regularly, mechanically and very expensively and with high precision, in order to keep the chances of unwanted disturbances of the light path during element change or element adjustment as small as possible. [0006] This problem is faced especially in confocal microscopes or laser scanning microscopes, in which a confocal slit with a detector unit is used, that either contains a detector screen on its side or acts as one. Since even with very large mechanical expenditure for the changeable or adjustable elements, influences of the light path for example by tipping errors or wedge errors at the optical element can never be completely ruled out, partially cost-effective correction mechanisms are provided in the prior art, to change the light path of the image with such pinhole-objectives. [0007] Thus in DE 101 47 481 A1 for example an adjustable confocal slit for a laser scanning microscope is described, that makes a displacement of the aperture possible, to be able to shift the confocal slit appropriately in tipping errors or wedge errors that are caused by adjustment or change of optical elements, so that an optimal image is always formed in the confocal microscope. The DE 101 07 210 C1 describes a similar approach, which likewise adjusts relevant elements in the optical arrangement. There, in a confocal microscope a focusing lens in the arrangement can be shifted transverse to the Z-axis of the light path. It can also be used to bring about an adjustment of the image in the confocal microscope. [0008] It is thus common in the approaches of the prior art, to change the optical arrangements in the confocal microscope, i.e. in the optical imaging arrangement--either by the change of the location of a confocal slit with respect to the object to be imaged or by the adjustment of other imaging elements of the imaging optics. Apart from a relatively large mechanical/optical effort necessary in these approaches, there exists a fundamental problem in this principle pursued in the state of the art, that the reproduction ratios are no longer comparable from time to time. A laborious new calibration of imaging scales can become necessary. SUMMARY OF THE INVENTION [0009] Therefore the purpose of this invention is to provide a correction device for an optical imaging arrangement, with which a correction can be applied without adjusting the optical image itself, especially without having to adjust the optical elements. [0010] According to the invention this task is solved with a correction device for an imaging optical arrangement exhibiting an optical path, wherein the device exhibits at least one plane parallel transparent plate, that is held in a mounting plate in the optical path and is movable around at least one axle by means of the mounting plate in a tipping movement and/or swiveling, in order to adjust a constant parallel misalignment of the light path by change of the tipping situation of the plate. [0011] The invention especially provides for a confocal microscope, whereby the microscope focuses a selected specimen area on a confocal slit, to which a detector unit is subordinate and whereby the plate is placed first in the optical path of the detector unit, in order to center the image. [0012] According to the invention the correction device has the advantage that a simple compensation or correction of errors developing in the image of the optical arrangement is possible. Especially simple environment or system temperature, radiation used by changeable or mobile elements in the arrangement, color defects due to wavelength or wavelength ranges can be corrected. Thereby depending on requirement a tipping and/or a swiveling plate with one axle can be sufficient. If one would like to plan a two axle parallel misalignment, one can either use two axle tipping and/or swiveling plates, or one can plan a two plate arrangement, one axle tipping and one swiveling. It is essential to the invention that the plane parallel plate can be tipped with the mounting plate in a defined and known way in the light path. For a two-axle adjustment each combination of tipping and swiveling is suitable. A combination of a tipping and swiveling movement is mechanically and relatively simple to realize and has surprisingly no disadvantages despite the shifting of the plane parallel plate along the Z-axis that arises during the swiveling. [0013] The correction brought about by the device can be done by a user manually, e.g. with an adjustment in the works. However, further training with a servo unit is particularly preferable, which records at least one operating parameter of the optical arrangement and which adjusts the tipping situation depending on the value of the operating parameter. The tipping situation can be put into calibration tables, for example. Also it is possible to optimize a correction by adjusting the tipping situation via active automatic control loops permanently and regularly or on requirement. For such an arrangement it is preferential to plan an automatic control loop that uses the tipping situation of the plate as correcting variable, in order to balance the described effects on the imaging optical arrangement. So, a possibly existing temperature or long-term drift error can be balanced in a simple manner in the optical arrangement. [0014] Since it is well known that the parallel misalignment by a plane parallel plate depends on the refractive index of the transparent disk material, color transverse errors can develop by a wavelength dependent parallel misalignment due to a dispersion of the disk material in polychromatic radiation in the light path of the optical arrangement. By structuring the plane parallel plate from one or several sub panels one can compensate such color transverse errors caused by the plane-parallel plate. [0015] According to the invention the correction device can be also adjusted for the correction of varying color transverse errors of the optical image that are dependent on the operating conditions. For example, if an optical arrangement is able to work with different wavelengths then a wavelength-dependent and thus operating condition-dependent color transverse error can occur. According to invention the correction device can then adjust the plane parallel plate depending on the wavelength range used in the optical arrangement and the resulting color transverse errors, so that in the final result despite operation with different wavelength ranges an unchanged optical image is focused in the arrangement. Naturally for this correction again, as previously mentioned, a suitable servo unit can be used, which can also exhibit an automatic control loop. [0016] The requirements of the accuracy or sensitivity, with which the drive handles the mounting plate, can also be preset, like the acceptable parallel misalignment range via the thickness of the plane parallel plate. [0017] The correction device according to the invention reduces, as previously mentioned, the requirements of adjustable optical elements in the focusing optical arrangement. This advantage is particularly important in the case of the already mentioned confocal microscope. In a confocal microscope a selected specimen area (Spot) is usually lit up and focused on a confocal slit in form of a so-called pinhole objective, followed by a detector. The radiation transmitted by this slit arrives with or without intermediate image on a detector; the detector can also serve as a confocal slit. The illumination can happen in a linear or punctiform pattern. [0018] Care must be taken to focus the specimen area completely on the confocal slit plane in the pinhole objective. This is above all made more difficult by the fact that a confocal microscope exhibits regularly exchangeable beam splitters, with which an adjustment of the microscope for different applications takes place, i.e. a change of the irradiated or selected wavelengths. The optical elements capable of being activated individually are accompanied by tipping or wedge errors, which can be reduced only with large effort in such a way that they do not disturb the image in the microscope. The same applies to changes of temperature or of long-term drift. The correction device according to the invention permits the realization of a confocal microscope, with which errors caused by changing optical elements can be simply corrected without interfering with the optical image. Additionally, the correction device can also be adjusted between the confocal slit and detector and so the optical path between slit and detector can be corrected suitably. [0019] Although in the case of confocal microscopes that use a pinhole objective before a locally non-resolving detector for detection, the correction already facilitates the mechanical requirements regarding the optical elements capable of being activated, the saving of effort is particularly noticeable, if the confocal microscope covers a locally disintegrating detector. This is for example the case with line-scanning laser scanning microscope that uses a slit diaphragm as pinhole slit before a detector line. It is then possible, to balance via a corresponding adjustment of the tipping situation of the plane parallel transparent plate, both a compensation of deviations perpendicular to the slit diaphragm and also a compensation of deviations parallel to the slit diaphragm. [0020] In the first case it is guaranteed that the light coming from the specimen meets the slit diaphragm accurately and is not off-center above or below the slit diaphragm. In the second case it is guaranteed that the light coming from the specimen meets the line detector correctly and there is no pixel misalignment between pictures of two detection channels in the system, each exhibiting its own line detector for example. Thus the confocal microscope according to the invention can reach a sub pixel accurate image registration during multi-channel training. [0021] The problem with a slit diaphragm that deviates perpendicularly to the direction line is solved in the confocal microscope by the fact that now a narrow detector line can be used, without necessitating a movement of the slit diaphragm and detector. The unnecessary loss of light flux and the consequent reduction of the signal-to-noise ratio in case of a misalignment (caused by tipping and wedge errors of changeable elements) with a lowering following an increase in resolution of the slit diaphragm can be avoided. [0022] Since the tipping or wedge errors of optical elements that can be activated individually are usually reproducible, the tipping situation of the transparent plane-parallel plate can be selected in a simple manner. With change of an optical element that can be activated, only a definite drive action of the plane parallel transparent plate is necessary in order to adjust the tipping situation newly required for the desired configuration of the microscope. Therefore a further training of the microscope according to the invention is preferential, in which the change or adjustable elements in the light path are provided and which records the submission and a configuration of change or adjustable elements as operating parameters and adjusts the tipping situation to be dependent on the value of the operating parameter. Continue reading about Correction device for an optical arrangement and confocal microscope with such a device... Full patent description for Correction device for an optical arrangement and confocal microscope with such a device Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Correction device for an optical arrangement and confocal microscope with such a device patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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