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  MicroscopeUSPTO Application #: 20070279734Title: Microscope Abstract: A confocal microscope has a specimen holding device for holding a specimen (18). The specimen (18) is illuminated by an illuminating unit (10). An optics unit (12) serves to direct radiation produced by the illuminating unit (10) toward the specimen (18) and to direct the radiation emitted by the specimen toward a detector unit (20). The confocal microscope also comprises an aperture diaphragm (34) that is placed in the beam path in front of the detector unit (20). In addition, a focusing lens (30) is provided in the beam path in front of the aperture diaphragm (34). The focusing lens (30) can be moved in order to adjust the confocal microscope, for example, in order to compensate for thermal stresses. (end of abstract)
Agent: Griffin & Szipl, PC - Arlington, VA, US Inventor: Jurgen MULLER USPTO Applicaton #: 20070279734 - Class: 359385000 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20070279734. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This application is a divisional of U.S. patent application Ser. No. 10/467,641, filed Jul. 1, 2004, which is a national stage application in the U.S. of International Patent Application No. PCT/EP02/01610, filed Feb. 15, 2002, and which claims priority from German Patent Application No. 101 07 210.4, filed Feb. 16, 2001. The entire disclosures of the above applications are incorporated herein by reference. FIELD OF THE INVENTION [0002] The invention relates to a microscope, particularly a confocal microscope for the single-molecule spectroscopy. In the following, any kind of magnifying means composed of two lens-arrangements will be understood by a microscope. BACKGROUND OF THE INVENTION [0003] Confocal microscopes are particularly suitable for the high-resolution measurement in the direction of the Z-axis, i.e., in longitudinal directions of the beam path of the microscope. To this end, confocal microscopes comprise an illuminating unit that typically is a laser. A specimen held by the specimen holding device is illuminated by the illuminating unit. To this end, an optics unit is provided which directs radiation produced by the illuminating unit toward the specimen and directs radiation given off by the specimen toward a detector unit. As a part of the optics, conventional confocal microscopes comprise a beam splitter. On the one hand, the beam splitter directs the light emitted from the illuminating unit toward the specimen and on the other hand, it leaves through the light reflected by the specimen so that it can reach a detector unit arranged behind the beam splitter in the beam path through an aperture diaphragm. As an illuminating unit, different illuminating units may be provided which, for example, produce visible light or also wavelengths in the non-visible range. In front of the detector unit, an aperture diaphragm is arranged and a focusing lens is arranged in front of the latter. [0004] By means of the focusing lens, the beam path is focused in the opening of the aperture diaphragm. [0005] By focusing the beam path in the opening of the aperture diaphragm, a relatively high light flux reaches the detector. Even a slight defocusing by displacing the object plane in Z-direction leads to a blurred image on the aperture diaphragm. This results in a smaller light flux since the focus of the focusing lens is no longer focused in the opening of the aperture diaphragm and thus, a smaller light flux comes through the diaphragm opening. Displacing the object plane in the X-Y-plane also results in a displacement of the focus in the plane of the aperture diaphragm. Thereby, the light quantity passing the aperture diaphragm is reduced since the focus is no longer focused in the opening of the aperture diaphragm. [0006] When confocal microscopes are used in high-throughput screening, the focus of the microscope objective is arranged in a biological or chemical specimen. Since the specimens are minimum quantities of specimen liquid having a volume in the microliter or nanoliter range, the confocal microscope used in high-throughput screening must be a highly precise device. This requirement exists all the more as specimens in the submicroliter range are examined in modern high-throughput screening installations. [0007] Because of the required very high accuracy of the focusing in the specimen, even very small temperature changes lead to the maladjustment of the confocal microscope. Particularly, a temperature-dependent maladjustment of the aperture diaphragm itself leads to the impairment of the accuracy of the microscope. Even slight maladjustments lead to that the illumination-side and the detection-side focus are no longer congruent. This results in a signal displacement and a considerable falsification of the measuring results. In addition, in the single-molecule detection, the assumption of the focus geometry is no longer valid in case of even a slight maladjustment. Further, the accuracy of the measuring results is influenced by inaccuracies of the laser by which the focus is displaced as well. Further, the measuring accuracy of confocal microscopes is influenced by the fact that the beam splitter provided in the optics unit has to be exchanged in dependence on the wavelength produced by the laser and given off by the specimen. Upon exchanging the beam splitter, slight position changes thereof occur. This also leads to a focus displacement and thus to a falsification of the measuring results. The beam splitter can displace relative to the excitation optics and the objective by temperature influences. [0008] For adjusting, it is known from U.S. Pat. No. 4,863,226 to provide an adjusting mechanism for the aperture diaphragm. By the adjusting mechanism, the aperture diaphragm can, be displaced in the direction of the X-Y- and Z-axis. Since the distance and the leading position between the aperture diaphragm and the detector arranged behind the aperture diaphragm have to be observed very closely, it is required to displace the entire detector unit together with the aperture diaphragm. Particularly with modern confocal microscopes, very complicated and sensitive detectors such as photo multiplier or spectographic multidetector arrangements are used. This results in that the detector unit occupies a large building space and is heavy. Therefore, the accurate positioning of the aperture diaphragm in the direction of the three axes is accompanied with considerable mechanical efforts. In this connection, it has to be considered that the adjustment of the aperture diaphragm has to be effected in the micrometer range. [0009] From U.S. Pat. No. 5,334,830, it is further known to arrange additional adjustable tilted mirrors for adjusting the aperture diaphragm in the beam path. Aligning the focus with the opening of the aperture diaphragm is thus effected by adjusting the tilted mirrors arranged in the beam path. By arranging additional components such as transparent camera wedges in the beam path, color errors as well as reflection losses occur. Further, the structural length of the microscope increases. [0010] It is the object of the invention to provide a microscope which is well adjustable with as small mechanical efforts as possible, particularly in case of highly precise requirements. SUMMARY OF THE INVENTION [0011] This object is solved, according to the invention, by the features of the following embodiments. In one embodiment of the present invention, a microscope, particularly a confocal microscope, for the single-molecule spectroscopy is provided that includes: a specimen holding device for holding a specimen, an illuminating unit, an optics unit directing radiation produced by the illuminating unit towards the specimen and directing radiation given off by the specimen toward a detector unit, an aperture diaphragm arranged in the beam path in front of the detector unit, and a focusing lens arranged in the beam path in front of the aperture diaphragm, characterized in that the focusing lens is vertically adjustable with respect to its optical axis. In another embodiment of the present invention, a microscope, particularly confocal microscope, for the single-molecule spectroscopy, is provided that includes: a specimen holding device for holding a specimen, an illuminating unit, an optics unit comprising a beam splitter, which directs radiation produced by the illuminating unit towards the specimen and radiation given off by the specimen toward a detector unit, an aperture diaphragm arranged in the beam path in front of the detector unit, and a stationary focusing lens arranged in the beam path in front of the aperture diaphragm, characterized in that the beam splitter is adapted to be tilted to align the radiation given off by the specimen with the central axis of the opening of the aperture diaphragm. BRIEF DESCRIPTION OF THE DRAWING [0012] Hereinafter, the invention is explained in detail with respect to a preferred embodiment with reference to the appended drawing. The drawing shows a schematic structure of a confocal microscope according to the invention. DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS OF THE INVENTION [0013] According to the invention, adjusting is effected either by adjusting the focusing lens through which the radiation given off by the specimen is fixed onto the aperture diaphragm or by adjusting a beam splitter that may be provided in the optics unit. According to the invention, the aperture diaphragm is thus at most displaced in Z-direction, i.e., in the direction of its optical axis. Preferably, the aperture diaphragm is stationary. [0014] The structure of the microscope according to the invention has the advantage that the adjustment of the aperture diaphragm together with the detector unit, which is possible with considerable mechanical efforts, is avoided in X-, Y- and Z-direction. The efforts are considerably reduced already when the aperture diaphragm, together with the detector unit, is exclusively adjustable in the direction of the Z-axis. Mechanically, the adjustment of the confocal microscope by adjusting the focusing lens and/or the beam splitter can be realized much more easily. [0015] Experiments have shown that in contrast to the prevailing opinion, the optical errors occurring by adjusting the focusing lens and/or the beam splitter are negligibly small. [0016] This also applies to confocal microscopes in particular. In this connection, it has to be guaranteed by the confocal microscope that a diffraction-limited measuring volume as small as possible is produced and observed. To this end, an objective with a numerical aperture as high as possible is used which is completely filled up by the illumination light. Thereby, the radius of the illuminated focus is defined. The size of the observed focus is adapted to this radius. With a given focus of the focus lens which amounts to between 160 and 200 mm in typical microscope arrangements, this adaptation can be achieved by selecting the diameter of the aperture diaphragm. To avoid significant losses of detected light as well as asymmetries of the measuring volume, the focus on the aperture diaphragm is only allowed to laterally shift by fractions of the diaphragm diameter. In case of confocal microscopes with high resolution, for example, this results in an objective focus of f=4 mm and a numerical aperture of 1.2. In case of a focus of the tube lens of 180 mm, the diameter of the aperture diaphragm amounts to about 30 .mu.m. This results in an admissible shift of the focus in the X-Y-plane of 5 .mu.m at most. An admissible angle error of 6'' corresponds thereto. [0017] In a first embodiment of the invention, the focusing lens is thus vertically adjustable to its optical axis, i.e., in the direction of the X- and/or Y-axis. Adjusting in the direction of the respectively other axis in the X-Y-plane can be effected by tilting the beam splitter. Particularly in case of confocal microscopes without a beam splitter or where the beam splitter cannot be exchanged, for example, and is thus preferably fixed in an non-adjustable position, the focusing with respect to the X-Y-plane is exclusively effected by displacing the focusing lens within this plane. [0018] In this embodiment, the adjustment in the direction of the Z-axis can be effected by displacing the aperture diaphragm together with the detector unit. But it is also particularly preferred to realize the adjustment in the direction of the Z-axis by displacing the focusing lens in the direction of its optical axis, i.e., in the direction of the Z-axis. [0019] The adjustment in the X-Y-plane is further possible by adjusting the beam splitter, preferably by tilting the beam splitter. Thereby, the beam path can be aligned with the central axis of the opening of the aperture diaphragm. The beam splitter can be adjusted in addition to the adjustment possibilities of the focusing lens. Continue reading... Full patent description for Microscope Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Microscope 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. Each week you receive an email with patent applications related to your keywords. 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