GRADUATED FILTER ASSEMBLY

Abstract

A graduated filter arrangement, an optical arrangement having a graduated filter arrangement, and uses of a graduated filter arrangement, where the filter arrangement has a graduated filter that is moveable in relation to a beam path and is provided in an intended filter plane, and a mirror in a mirror plane. The mirror plane and the intended filter plane are aligned fixedly in relation to one another and relative to one another in such a way that a beam of light rays that is incident at an angle of incidence along the beam path is reflected, at least in part, between the graduated filter and the mirror in such a way that there at least is a two-fold deflection of the incident light ray by the graduated filter arrangement and the reflected light ray is reflected as a beam of reflected light rays at a deflection angle. The optical effect of a present angle error between the intended filter plane and an actual filter plane provided by the current relative position of the chief plane of the graduated filter is reduced as a consequence of the at least two-fold deflection, and the deflection angle remains constant.

Claims

1. A graduated filter arrangement comprising a graduated filter that is moveable in relation to a beam path and provided in an intended filter plane, and a mirror in a mirror plane, said mirror plane and said intended filter plane being aligned fixedly in relation to one another and relative to one another in such a way that a beam of light rays that is incident at an angle of incidence along the beam path is reflected, at least in part, between the graduated filter and the mirror in such a way that there is an at least two-fold deflection of the incident light ray by the graduated filter arrangement, and said reflected light ray is being reflected as a beam of light rays from the graduated filter arrangement at a deflection angle, wherein a present angle error in the form of a tilt angle between the intended filter plane and an actual filter plane provided by the current relative position of a chief plane of the graduated filter is reduced as a consequence of the at least two-fold deflection, and the deflection angle remains constant.

2. The graduated filter arrangement as claimed in claim 1, wherein said mirror is embodied as a retroreflector.

3. The graduated filter arrangement as claimed in claim 1, wherein said incident beam of light rays is reflected from the graduated filter to the mirror and is reflected or reflectable back to the graduated filter from said mirror.

4. The graduated filter arrangement as claimed in claim 1, further comprising an optical lens arranged between the graduated filter and the mirror.

5. The graduated filter arrangement as claimed in claim 1, wherein said graduated filter is embodied on a side face of a pentaprism and the mirror is formed by one of the other side faces of the pentaprism.

6. The graduated filter arrangement as claimed in claim 5, further comprising an optical compensation element is disposed downstream of the graduated filter on its side face facing away from the mirror.

7. The graduated filter arrangement as claimed in claim 5, wherein said compensation element is embodied as a prism.

8. The graduated filter arrangement as claimed in claim 1, wherein said filter arrangement is embodied to be displaceable along an axis.

9. The graduated filter arrangement as claimed in claim 8, further comprising a carriage that is displaceable along said axis.

10. An optical arrangement comprising a graduated filter arrangement as claimed in claim 1.

11. The use of a graduated filter arrangement as claimed in claim 1 for reducing the optical effect of a tilt angle between an intended filter plane and an actual filter plane provided by a chief plane of a graduated filter.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0034] The invention is explained in more detail below on the basis of exemplary embodiments and figures. In the figures:

[0035] FIG. 1 is a schematic illustration of a beam profile on a graduated filter (prior art);

[0036] FIG. 2 is a schematic illustration of a first exemplary embodiment of a graduated filter arrangement according to the invention in cross section;

[0037] FIG. 3 is a schematic illustration of a second exemplary embodiment of a graduated filter arrangement according to the invention in cross section;

[0038] FIG. 4 is a schematic illustration of a third exemplary embodiment of a graduated filter arrangement according to the invention in cross section;

[0039] FIG. 5 is a schematic illustration of a fourth exemplary embodiment of a graduated filter arrangement according to the invention in cross section;

[0040] FIG. 6 is a schematic illustration of a fifth exemplary embodiment of a graduated filter arrangement according to the invention in a perspective view; and

[0041] FIG. 7 is a schematic illustration of a sixth exemplary embodiment of a graduated filter arrangement according to the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] In the schematically illustrated drawings of the exemplary embodiments, the same reference signs denote the same technical elements.

[0043] The beam profile on a graduated filter 2 illustrated in FIG. 1 substantially lies in an XZ-plane XZ of a Cartesian coordinate system with an X-axis X, a Y-axis Y and a Z-axis Z.

[0044] In a first exemplary embodiment of a graduated filter arrangement 1, which is illustrated in FIG. 2, a pentaprism 10 is present, said pentaprism being shown in a lateral illustration and having first to fifth side faces 10.1, 10.2, 10.3, 10.4 and 10.5. The graduated filter 2 is applied to the second side face 10.2. The fourth side face 10.4 is mirrored and acts as a mirror 4. The plane of the second side face 10.2 coincides with a filter plane 2.1, which corresponds to an actual filter plane of the graduated filter 2 and in which the graduated filter 2 extends. The fourth side face 10.4 coincides with a mirror plane 4.1. The intended filter plane and the actual filter plane 2.1 coincide in the non-tilted state of the graduated filter 2.

[0045] In the exemplary embodiments, the graduated filter arrangement 1 is illustrated schematically as part of an optical arrangement 16, in particular a microscope 16.

[0046] An incident light ray 6 of an illumination light enters into the pentaprism 10 through the fifth side face 10.5 and a portion thereof is reflected at the filter plane 2.1 by the effect of the graduated filter 2.

[0047] A non-reflected portion of the light ray 6 passes through the graduated filter 2 and propagates as transmitted light ray 8.

[0048] The reflected portion of the light ray 6 is reflected again at the mirror plane 4.1 and emerges as a reflected light ray 7 from the first side face 10.1.

[0049] The incident light ray 6 and the reflected light ray 7 include the deflection angle .

[0050] By way of example, should the graduated filter arrangement 1 be tilted about the Y-axis Y through the tilt angle , shown here in a schematic fashion and with exaggerated dimensions for reasons of improved clarity, the deflection angle remains constant due to the effect of the two-fold reflection between graduated filter 2 and mirror 4 in the case of a simultaneously fixed relative position between graduated filter 2 and mirror 4.

[0051] In a second exemplary embodiment of the graduated filter arrangement 1, in FIG. 3, a pentaprism 10 is present with a shape that has changed in relation to the first exemplary embodiment. In the case of a tilt movement about the Y-axis Y and with the tilt angle , the deflection angle remains constant.

[0052] In a third exemplary embodiment, an L-shaped or U-shaped graduated filter arrangement 1 is illustrated instead of a pentaprism 10 (FIG. 4). The graduated filter 2 is formed on a surface of the carrier 3. The carrier 3 has a rigid connection to the mirror 4 by means of a mirror base 12. The mirror 4 is formed as a reflective layer on an inclined plane surface of the mirror base 12. As a consequence of the rigid connection between graduated filter 2 with carrier 3 and mirror 4, these are aligned fixedly in relation to one another and relative to one another in such a way that a beam of light rays 6 that is incident at an angle of incidence along the beam path is reflected, at least in part, between the graduated filter 2 and the mirror 4 in such a way that there is a two-fold deflection of the incident light ray 6 by the graduated filter arrangement 1. The reflected light ray 7 is guided is a free ray between the graduated filter 2 and the mirror 4.

[0053] FIG. 5 shows a fourth exemplary embodiment of the graduated filter arrangement 1. It is embodied as a pentaprism 10 and assembled on a carriage 15 by means of fastening elements 14, said carriage rendering the graduated filter arrangement 1 displaceable along the X-axis X.

[0054] By way of example, the graduated filter 2 is displaced into an image plane of a microscope 16, for example, in order to strike other positions on the graduated filter 2. On account of the optical properties of the pentaprism 10, the reflected light ray 7 is always deflected through a deflection angle of 90 in relation to the incident light ray 6, independently of the tilt angle .

[0055] Thus, if there is an unwanted tilt in the direction of the Y-axis Y as a result of displacing the carriage 15 with the graduated filter arrangement 1, this does not lead to a change in the deflection angle and in the reflected light ray 7. Although tilt movements about the X-axis X, illustrated horizontally in FIG. 5, still lead to changes in the deflection angle (see FIGS. 2 to 4), these are less than tilt movements about the Z-axis Z on account of the usually relatively long installation length of the carriage 15. The changes in the deflection angle in the case of a tilt movement about the X-axis X only have exactly the same size as the changes in the relative mechanical position.

[0056] In order to compensate a deflection of the transmitted light ray 8, a compensation element 11 in the form of a further prism is also fastened to the carriage 15 in the beam path of the transmitted light ray 8, and so the graduated filter arrangement 1 and the compensation element 11 move together and, where appropriate, are also tilted together. In this way, the transmitted light beam 8 always travels at a constant angle, i.e., in the same direction.

[0057] In the fifth exemplary embodiment of the graduated filter arrangement 1, illustrated in FIG. 6 in perspective fashion, a section of a microscope 16 with a graduated filter arrangement 1 is shown schematically.

[0058] In a microscope 16, which is typically embodied as a laser scanning microscope (LSM), there is also a graduated filter 2, denoted as a main color splitter, as a central functional element, said graduated filter separating a detection beam path 9 from an excitation beam path 5, both of which are symbolized by arrows. Here, a beam of incident light rays 6 is reflected at the graduated filter 2, deflected by the effect of the mirror 4 and the graduated filter 2 and steered onto a sample (not illustrated) along the excitation beam path 5 as a reflected light ray 7.

[0059] From the sample, the fluorescence signal, which is shifted in terms of wavelength, passes through the microscope 16 as detection light, once again reaches the graduated filter 2 and it is now transmitted there on account of the longer wavelength (transmitted light ray 8).

[0060] In the further course of the detection beam path 9, the light of the transmitted light ray 8 reaches a pinhole or an Airy scan detector (both not shown), for example. Relative position tolerances of the graduated filter 2 have an effect on the reflected light ray 7. As a consequence, a slightly different point in the sample is struck after a change in the tilt angle than prior to the change. Detection light of the impact position is imaged into the pinhole plane with a detection-side offset and it misses the pinhole, causing a loss of signal.

[0061] The beam of incident light rays 6 is reflected onto the mirror 4 by the graduated filter 2 and returns back to the graduated filter 2 from said mirror. The light of the light ray 7 that has now been reflected twice by the graduated filter 2 is directed onto the sample along the excitation beam path 5. Detection light received by the sample is incident on the graduated filter 2 and guided along the detection beam path 9 as a transmitted light ray 8 on account of its modified wavelength, to which the graduated filter 2 is transparent.

[0062] All angle errors exactly compensate one another in the present configuration of the graduated filter arrangement 1. A graduated filter 2 is imaged onto itself for the purposes of avoiding a lateral offset. For detection purposes, the graduated filter 2 is used in a simple pass, and so no disadvantages arise in relation to the prior art.

[0063] The solution using an adjustment mirror in the excitation beam path 5, by means of which a respective deviation of actual and intended filter plane is compensated where necessary and which was previously used in the prior art, is not required if use is made of the graduated filter arrangement 1 according to the invention. This advantageously allows tracking of the adjustment mirror to be dispensed with in the case of a change in relative position of the graduated filter 2. Advantageously, a change mechanism for the graduated filter 2 can have a simpler configuration.

[0064] A further configuration option is illustrated in FIG. 7, where there is no imaging of the graduated filter 2 onto itself, in contrast to the exemplary embodiment shown in FIG. 6. Instead, a retroreflector is arranged as a mirror 4 for the purposes of deflecting the incident light ray 6 so that the light ray 7 reflected at the graduated filter 2 can be reflected back without a change in angle. The beam path of the beam of reflected light rays 7 in or on the mirror 4 is not illustrated.

[0065] While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. The embodiments were chosen and described in order to best explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.

REFERENCE SIGNS

[0066] 1 Graduated filter arrangement [0067] 2 Graduated filter [0068] 2.1 Actual filter plane [0069] 3 Carrier [0070] 4 Mirror [0071] 4.1 Mirror plane [0072] 5 Excitation beam path [0073] 6 Incident light ray [0074] 7 Reflected light ray [0075] 8 Transmitted light ray [0076] 9 Detection beam path [0077] 10 Pentaprism [0078] 10.1 First side face [0079] 10.2 Second side face [0080] 10.3 Third side face [0081] 10.4 Fourth side face [0082] 10.5 Fifth side face [0083] 11 Compensation element [0084] 12 Mirror base [0085] 13 Optical lens [0086] 14 Fastening element [0087] 15 Carriage [0088] 16 Optical arrangement/microscope [0089] X X-axis [0090] Y Y-axis [0091] Z Z-axis [0092] Deflection angle [0093] Tilt angle