CATADIOPTRIC-OPTICAL ARRANGEMENT

Abstract

An optical arrangement is provided. The optical arrangement has a center axis, an object side, an image side, and a catadioptric arrangement. The optical arrangement has an installation space of no more than 25 millimeters from the object side to the image side along the center axis, and a linear obscuration of no more than 60 percent.

Claims

1. An optical arrangement, comprising: a center axis; an object side; an image side; and a catadioptric arrangement, wherein the optical arrangement has an installation space of no more than 25 millimeters from the object side to the image side along the center axis, and a linear obscuration of no more than 60 percent.

2. The optical arrangement as claimed in claim 1, wherein the catadioptric arrangement comprises a first, partly reflective optical component with a front side arranged on the object side and a back side arranged on the image side, and a second, partly reflective optical component with a front side arranged on the object side and a back side arranged on the image side, the optical components being arranged in succession in the beam path along the center axis such that the first optical component is arranged on the image side of the second optical component, wherein the first optical component comprises a radially inner region and a radially outer region in relation to the center axis, the inner region being configured to at least partly transmit light incident from the object side and the back side of the outer region being configured to reflect light incident from the object side, wherein the second optical component comprises a radially inner region and a radially outer region in relation to the center axis, the outer region being configured to transmit light incident from the object side and the inner region being configured to reflect light incident from the image side, and wherein at least one first refractive surface with refractive power and one second refractive surface with refractive power are arranged in the beam path between the back side of the first optical component and the front side of the second optical component.

3. The optical arrangement as claimed in claim 2, wherein at least one of: the first refractive surface with refractive power is formed by the front side of the first optical component, and the second refractive surface with refractive power is formed by the back side of the second optical component.

4. The optical arrangement as claimed in claim 2, wherein the first optical component is configured such that only the front side and/or the back side have refractive power and the image plane is arranged immediately on the image side of the first optical component.

5. The optical arrangement as claimed in claim 2, wherein at least one third optical component is arranged geometrically, and in the beam path, between the first optical component and the second optical component.

6. The optical arrangement as claimed in claim 5, wherein the at least one third optical component is configured to be refractive and/or the at least one third optical component is configured to correct at least one imaging aberration.

7. The optical arrangement as claimed in claim 2, wherein the radial extents of individual optical components of the optical arrangement deviate from one another by no more than 2 millimeters or no more than 30 percent.

8. The optical arrangement as claimed in claim 2, wherein the outer region and the inner region on the back side of the first optical component have different surface shapes from one another and/or the outer region and the inner region on the front side and/or on the back side of the second optical component have different surface shapes from one another.

9. The optical arrangement as claimed in claim 1, wherein at least one field lens is arranged in the beam path and/or geometrically between the catadioptric arrangement and the image side.

10. The optical arrangement as claimed in claim 9, wherein at least one field lens group comprising at least one lens with positive refractive power and/or at least one lens with negative refractive power is arranged in the beam path and/or geometrically between the catadioptric arrangement and the image side of the optical arrangement.

11. The optical arrangement as claimed in claim 9, wherein the field lens group comprises a first lens or lens group with positive refractive power and a second lens or lens group with negative refractive power arranged upstream of the first lens or lens group in the beam path.

12. The optical arrangement as claimed in claim 9, wherein the catadioptric arrangement comprises a front side arranged on the object side, a back side arranged on the image side and, in relation to the center axis, a radially inner region and a radially outer region, with the inner region on the back side being configured to at least partly transmit light incident on the object side and having negative refractive power.

13. The optical arrangement as claimed in claim 9, wherein the catadioptric arrangement comprises a first, partly reflective optical component with a front side arranged on the object side and a back side arranged on the image side, and a second, partly reflective optical component with a front side arranged on the object side and a back side arranged on the image side, the optical components being arranged in succession in the beam path along the center axis such that the first optical component is arranged on the image side of the second optical component, wherein the first optical component comprises a radially inner region and a radially outer region in relation to the center axis, the inner region being configured to at least partly transmit light incident from the object side and the back side of the outer region being configured to reflect light incident from the object side, and wherein the second optical component comprises a radially inner region and a radially outer region in relation to the center axis, the outer region being configured to transmit light incident from the object side and the inner region being configured to reflect light incident from the image side.

14. The optical arrangement as claimed in claim 13, wherein the radially inner region of the first optical component has negative refractive power.

15. The optical arrangement as claimed in claim 1, wherein a field lens group is arranged on the image side of the catadioptric arrangement and the optical arrangement defines an image plane, wherein the optical arrangement has an installation length L.sub.s measured from the vertex of the first optical surface to the image plane and the field lens group has a paraxial focal length f′FL less than zero (f′.sub.FL<0), and wherein the absolute value of the paraxial focal length f′.sub.FL is less than the focal length L.sub.s (|f′.sub.FL|<L.sub.s).

16. The optical arrangement as claimed in claim 1, wherein at least one field lens is arranged on the image side of the catadioptric arrangement and the optical arrangement defines an image plane with an imaging surface with a diameter D.sub.1, with the optical arrangement having an image-side clear optical diameter D.sub.2 from the back side of the catadioptric arrangement, with the ratio of the clear optical diameter D.sub.2 to the diameter D.sub.1 of the imaging surface being less than 1.

17. The optical arrangement as claimed in claim 1, wherein at least one field lens is arranged on the image side of the catadioptric arrangement and the optical arrangement defines an image plane, wherein the optical arrangement has a focal length f′ and an installation length L.sub.s as measured from the vertex of the first optical surface to the image plane, and wherein the ratio of the focal length f′ to the installation length L.sub.s is larger than 2.

18. The optical arrangement as claimed in claim 1, wherein at least one field lens is arranged on the image side of the catadioptric arrangement and the optical arrangement defines an image plane, wherein the optical arrangement has an imaging scale β, a distance FWD of an object plane from the vertex of the first optical surface and an installation length Ls as measured from the vertex of the first optical surface to the image plane, and wherein the product of the imaging scale β and the quotient of the distance FWD and the installation length L.sub.s is larger than 2.

19. The optical arrangement as claimed in claim 1, wherein the chief ray angle of the beam path immediately prior to leaving the catadioptric arrangement at the backside thereof, where the catadioptric arrangement has a refractive index n.sub.2, has a direction cosine rvl.sub.2, and wherein the chief ray angle of the beam path in an image plane in an image-side medium with a refractive index n.sub.1 (at the detector) has a direction cosine rvl.sub.1, with the following applying: (n.sub.2*rvl.sub.2)/(n.sub.1*rvl.sub.1)<1.

20. The optical arrangement as claimed in claim 1, wherein the optical arrangement has at least one of a negative imaging scale, a positive entrance pupil position, and a positive exit pupil position.

21. The optical arrangement as claimed in claim 1, wherein the beam path has an even number of reflections.

22. The optical arrangement as claimed in claim 1, wherein the optical arrangement has an aperture stop and the distance between an object plane defined by the optical arrangement and the aperture stop is larger than the distance between the aperture stop and an image plane defined by the optical arrangement.

23. The optical arrangement as claimed in claim 1, wherein at least one of the optical surfaces in the beam path is configured to be continuous and at least one time continuously differentiable.

24. The optical arrangement as claimed in claim 1, wherein the optical arrangement has a linear obscuration of no more than 50 percent.

25. The optical arrangement as claimed in claim 1, wherein the optical arrangement is at least one of configured as a microscope, and designed for a mobile device.

26. An objective comprising an optical arrangement as claimed in claim 1.

27. An image capture apparatus or image reproduction apparatus comprising an objective as claimed in claim 26.

28. A device, comprising: an image capture apparatus; an image reproduction apparatus; or an optical arrangement as claimed in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0078] The disclosure will now be described with reference to the drawings wherein:

[0079] FIG. 1 schematically shows the beam path for generating a volume-faithful image representation.

[0080] FIG. 2 schematically shows the beam path through a catadioptric arrangement for the purpose of illustrating the obscuration.

[0081] FIG. 3 schematically shows options for reducing the obscuration.

[0082] FIG. 4 schematically shows an optical arrangement according to a first exemplary embodiment of the disclosure.

[0083] FIG. 5 schematically shows an optical arrangement according to a second exemplary embodiment of the disclosure.

[0084] FIG. 6 schematically shows an optical arrangement according to a third exemplary embodiment of the disclosure.

[0085] FIG. 7 schematically shows an optical arrangement according to a fourth exemplary embodiment of the disclosure.

[0086] FIG. 8 schematically shows an optical arrangement according to a fifth exemplary embodiment of the disclosure.

[0087] FIG. 9 schematically shows an optical arrangement according to a sixth exemplary embodiment of the disclosure.

[0088] FIG. 10 schematically shows an optical arrangement according to a seventh exemplary embodiment of the disclosure.

[0089] FIG. 11 schematically shows an optical arrangement according to an eighth exemplary embodiment of the disclosure.

[0090] FIG. 12 schematically shows an optical arrangement according to a nineth exemplary embodiment of the disclosure.

[0091] FIG. 13 schematically shows an optical arrangement according to a tenth exemplary embodiment of the disclosure.

[0092] FIG. 14 schematically shows an optical arrangement according to an eleventh exemplary embodiment of the disclosure.

[0093] FIG. 15 schematically shows an optical arrangement according to a twelfth exemplary embodiment of the disclosure.

[0094] FIG. 16 schematically shows an optical arrangement according to a thirtheenth exemplary embodiment of the disclosure.

[0095] FIG. 17 schematically shows an optical arrangement according to a fourteenth exemplary embodiment of the disclosure.

[0096] FIG. 18 schematically shows an optical arrangement according to a fifteenth exemplary embodiment of the disclosure.

[0097] FIG. 19 schematically shows a device according to an exemplary embodiment of the disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0098] The disclosure is explained in larger detail below on the basis of exemplary embodiments and with reference to the accompanying figures. Although the disclosure is more specifically illustrated and described in detail with the preferred exemplary embodiments, nevertheless the disclosure is not restricted by the examples disclosed and other variations can be derived therefrom by a person skilled in the art, without departing from the scope of protection of the disclosure.

[0099] The figures are not necessarily accurate in every detail and to scale, and can be presented in enlarged or reduced form for the purpose of better clarity. For this reason, functional details disclosed here should not be understood to be limiting, but merely to be an illustrative basis that gives guidance to a person skilled in this technical field for using the present disclosure in various ways.

[0100] The expression “and/or” used here, when it is used in a series of two or more elements, means that any of the elements listed can be used alone, or any combination of two or more of the elements listed can be used. For example, if a structure is described as containing the components A, B and/or C, the structure can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

[0101] FIG. 1 schematically shows the beam path 17 for generating a volume-faithful image representation and has already been described in the introductory part of the description. A first converging lens 7 generates image representations A.sub.0′ and A.sub.1′ of objects A.sub.0 and A.sub.1, but, as shown at the top of FIG. 1, these image representations do not correspond in terms of their size relationships to the objects. At the bottom of FIG. 1, a further field lens in the form of a second converging lens 8 is used to adjust the direction of the chief ray 9 so that the size relationship of the generated image representations A.sub.0′ and A.sub.1′ corresponds to the size relationship the objects A.sub.0 and A.sub.1 have with respect to one another. The center axis of the lenses 7 and 8, which coincides with the optical axis, is identified by the reference sign 2.

[0102] FIG. 2 schematically shows the beam path through a catadioptric arrangement including a first optical surface 31 (primary mirror), which is reflective in a radially outer region, and a second reflective optical surface 32 (secondary mirror), and illustrates the calculation of the obscuration already described above. The entrance pupil or stop is identified by the reference sign 18. Light radiated in from the left in the FIG. is initially reflected by the first reflective optical surface 31, with some of the light being shadowed by the second reflective optical surface 32. Subsequently, the light reflected by the first reflective optical surface 31 is reflected by the second reflective optical surface 32 and passes the first optical surface 31 in a radially inner region. FIG. 2, bottom identifies the direction cosine of the marginal ray R.sub.0 by an arrow rvl.sub.0 and the direction cosine of the light ray R.sub.1 by an arrow rvl.sub.1.

[0103] FIG. 3, which has already been described above, illustrates options for reducing the obscuration. In this case, the image plane or a detector is identified by reference sign 6 and a diverging lens for expanding the beam path 17 is identified by reference sign 27.

[0104] A first exemplary embodiment variant of the present disclosure is explained in more detail hereinafter on the basis of the exemplary embodiments shown schematically in FIG. 4 to 9. The optical arrangement 1 shown includes a center axis 2, which coincides with the optical axis in the examples shown, an object side 3, and an image side 4. In this case, the object inside 3 faces an object to be imaged or an object plane 5 and the image side 4 faces an image plane 6 or a detector, for example a camera, arranged in the region of the image plane. Moreover, the optical arrangement 1 includes a catadioptric arrangement 10.

[0105] The catadioptric arrangement 10 includes a first, partly reflective optical component 11 and a second, partly reflective optical component 12. These are configured as lenses in the example shown. The first, partly reflective optical component 11 includes a front side 13 and a back side 14. The second, partly reflective optical component 12 likewise includes a front side 15 and a back side 16. In this case, the front sides 13 and 15 face the object side 3 and the back sides 14 and 16 face the image side 4. The first optical component 11 and the second optical component 12 are arranged in succession in the beam path 17 along the center axis 2 such that the first optical component 11 is arranged on the image side of the second optical component 12.

[0106] In relation to the center axis 2, the first optical component 11 includes a radially inner region 21 and a radially outer region 22. In this case, the inner region 21 is configured to be at least partly transparent to, or at least partly transmit, light incident from the object side. The outer region 22 is configured to reflect light incident from the object side. To this end, the back side 14 of the first optical component 11 has a reflective coating 23. The latter is configured to be concave on the object side (convex on the image side) in the example shown.

[0107] In relation to the center axis 2, the second optical component 12 includes a radially inner region 24 and a radially outer region 25. In this case, the outer region 25 is configured to be transparent or transmissive to light incident from the object side. The inner region 24 is configured to be at least partly transparent to, or at least partly transmit, light incident from the object side and configured to reflect light incident from the image side. To this end, the front side 15 of the second optical component 12 has a reflective coating 26. The latter is configured to be convex on the image side (concave on the object side) in the example shown.

[0108] A plane parallel plate 28 is arranged between the back side 14 of the first optical component 11 and the image plane 6. This plane parallel plate may be a transparent cover.

[0109] The present exemplary embodiment is a microscope objective with an imaging scale of −1:0.8, which has a very large working distance of 28 mm in the case of an overall installation length of 8.5 mm. The system has a front stop, which is to say the system stop 18 is located in front of the actual optical system. The stop 18 may also be located within the optical arrangement 1. What is decisive for the stop position is that, when necessary, a diameter-variable stop can easily be realized from a mechanical point of view. For example, the stop 18 may also be located between the two optical components 11 and 12.

[0110] The shown optical components 11 and 12 may be configured to be rotationally symmetric, for example. In the example shown, the light enters into the optical arrangement 1 through a very large entrance pupil with virtually 8 mm diameter and is refracted by the front side 15 and the back side 16 of the second optical component 12 in its radially outer region 25. The front side 15 and the back side 16 of the second optical component 12 and the front side 13 of the first optical component 11 may have an aspherical embodiment. The reflective coating 23 of the first optical component 11 acts like a converging Mangin mirror for the incident light and it reflects the light back to the second optical component 12. The reflective coating 26 of the second optical component 12 acts like a diverging Mangin mirror for the incident light and it reflects the light back to the first optical component 11. Finally, the light once again passes through the first optical component 11 in the region near the axis, where this first optical component acts in the inner region 21 as a transmissive lens. No further optical elements with refractive power are passed after this point, and the light is incident in the image plane 6.

[0111] The front side 15 of the second optical component 12 has a different surface shape at the transition between the outer region 25 and the inner region 24, which is to say between the transmissive and the reflective region, than in the aforementioned regions. Although the transition is continuous, it is not differentiable, which is to say it has a kink. From a mounting technological point of view, the kink may be mechanically rounded-off by way of a chamfer. Moreover, it may also be embodied in discontinuous fashion.

[0112] The optical arrangement 1 shown in FIG. 4 has a linear obscuration of 40%. Linear obscuration means that, in the entrance pupil, the interior 40% of the entrance pupil coordinates cannot pass through the optical arrangement or will not be imaged. This is tantamount to an obscuration of 16% of the area of the entrance pupil (=40%.sup.2 or 0.4.sup.2).

[0113] Obscuration decisively occurs during the light entrance into the optical arrangement 1 at the front side 15 of the second optical component 12. Here, the rays in the inner region of the pupil 18 are blocked at the central reflective coating 26. A further obscuration may occur during the reflection at the back side 14 of the first optical component 11, specifically if entering light rays pass through the non-reflective central region, which is to say the inner region 21, and are not reflected back to the second optical component 12.

[0114] The front side 13 of the first optical component 11 and/or the back side 16 of the second optical component 12 are designed to correct aberrations. In particular, they may be designed as spherical or aspherical surfaces or free-form surfaces. In the example shown, all surfaces and surface regions shown of the first optical component 11 and second optical component 12 have an aspherical configuration.

[0115] In principle, the first optical component 11 and the second optical component 12 may consist of different optical materials. In the example shown, the second optical component 12 has a refractive index of 1.493 and an Abbe number of 51.3 and acts as a crown material in this case. The first optical component 11 has a refractive index of 1.589 and an Abbe number of 26.2 and acts as a flint material in this case.

[0116] The first optical component 11 and the second optical component 12 have comparable diameters. The diameters may be identical or deviate from one another by no more than 30 percent.

[0117] The exemplary embodiment shown in FIG. 5 is very similar to the exemplary embodiment shown in FIG. 4. The essential difference is that the use of a second optical material was dispensed with in this case. The first optical component 11 and the second optical component 12 are made of crown-type material. In other words, this relates to a one-material system. Alternatively, the first optical component 11 and the second optical component 12 may be made of flint-type material or may include such material.

[0118] The exemplary embodiment shown in FIG. 6 shows the design principle described in the preceding exemplary embodiments for a conventional photographic objective, which is to say for imaging from an infinite object distance to an image receiver. This is an optical arrangement 1 configured as an objective, having a focal length of f′=22 mm in the case of an installation space of only L.sub.s=8,5 m, as measured along the center axis 2. Purely from a mathematical point of view, the telephoto factor is therefore F=0.39. Once again, this relates to a one-material system. In this example, the obscuration of the optical arrangement 1 is 40 percent.

[0119] The optical arrangement 1 moreover includes a third optical component 19 arranged geometrically or spatially, and in the beam path 17, between the first optical component 11 and the second optical component 12. In the beam path 17, light passes through the third optical component 19, which is configured as a refractive lens, three times. It has a front side 29 and a back side 30. The front side 29 and the back side 30 of the third optical component 19 can be embodied to be spherical or aspherical, or as a free-form surface.

[0120] The exemplary embodiment shown in FIG. 7 shows an optical arrangement 1 in the form of a microscope objective which has the optical characteristics of the first exemplary embodiment. The reflective coating 26 of the second optical component 12 is arranged on the back side 16, which is to say the image-facing side, in this example. The reflective coating 26 has a convex configuration on the image side. It has a uniform shape which is continuously differentiable any desired number of times, which is to say it has a uniform polynomial surface description over the entire area of the back side 16 of the second optical component 12. In a manner analogous to the 3rd exemplary embodiment, a third optical component 19 in the form of a lens through which light passes three times in the beam path 17 is arranged geometrically, and in the beam path 17, between the first optical component 11 and the second optical component 12.

[0121] In contrast to the above-described exemplary embodiments, in which the front side 15 of the second optical component 12 was not continuously differentiable, the obscuration is 50% in this exemplary embodiment and in the two subsequent exemplary embodiments. The uniform, which is to say continuous and differentiable, surface design is advantageous for the manufacturing of the surfaces and reduces production costs. Moreover, it is advantageous in the context of centering the respective optical components and the precise positioning of the reflective partial regions.

[0122] The fifth exemplary embodiment shown in FIG. 8 differs from the fourth exemplary embodiment shown in FIG. 7 in that the front side 29 of the third optical component 19 rests against the back side 16 of the second optical component 12. Moreover, the second optical component 12 is configured as a lens which is passed once. A further structural difference is that the second reflection occurs not on the (convex) back side of the second optical component 12 but on the (concave) front side of the third optical component 19. Formally, the catadioptric arrangement is therefore formed by the first optical component 11 and the third optical component 19 in this exemplary embodiment.

[0123] In the sixth exemplary embodiment shown in FIG. 9, the principle according to the disclosure is once again applied to an optical arrangement 1 which is configured as a photographic objective and which has a collimated beam input. The reflective coating 26 is once again arranged on the back side 16 of the second optical component 12. The third optical component 19 is configured as a lens through which light passes thrice.

[0124] A second embodiment variant of the present disclosure is explained in more detail hereinafter on the basis of the exemplary embodiments shown schematically in FIG. 10 to 13.

[0125] In the configuration shown in FIG. 10, the catadioptric arrangement 10 is configured as a single catadioptric component. The latter has a front side 33, arranged on the object side, and a back side 34, arranged on the image side. The front side 33 includes a radially inner region 35, which is configured to reflect light incident from the image side, and a radially outer region 36, which is designed to transmit. The back side 34 has a radially inner region 37, which is configured to transmit light incident from the object side, and a radially outer region 38, which is designed to reflect light incident from the object side. In this case, the reflective region of the front side 33 is shaped to be concave from the outside, which is to say convex in the beam path 17 or on the image side, and the reflective region of the back side 34 is shaped to be convex from the outside, which is to say concave in the beam path.

[0126] A field lens group 40 and optionally a plane parallel plate 28 are arranged geometrically or spatially, and in the beam path 17, between the back side 34 of the catadioptric arrangement or the catadioptric component 10 and the image plane 6, with the plane parallel plate 28 being arranged on the image side of the field lens group 40. The field lens group 40 includes a lens unit with negative refractive power, consisting of three refractive diverging lenses 40, 41 and 43 in the present case, and a lens unit with positive refractive power, including a refractive converging lens 44 in the present case.

[0127] As a rule, the front side 33 of the catadioptric arrangement 10 does not have a uniform surface shape. The reflective radially inner region 35 is usually described by a different surface equation to the radially outer, transmissive region 36. Typically, the two surface descriptions are at least configured such that they merge continuously into one another. Although this may apply to the back side 34, it need not necessarily apply there.

[0128] The basic course of the beam path 17, in particular within the catadioptric component 10, substantially corresponds to the beam path described in conjunction with the already-described exemplary embodiments. There would be a real intermediate image upon exit of the light from the radially inner region 37 of the back side 34 in the absence of the field lens group 40 behind the back side 34. The chief ray diverges away from the optical axis 2 upon exit of the light from the catadioptric component 10, which is to say the pupil of the air situated downstream the back side 34 is virtual and located upstream of the back side 34.

[0129] The field lens group 40 forms a pronounced retrofocus structure of negative and positive refractive power. The light leaves the catadioptric component or the catadioptric arrangement 10 with a convergent marginal ray angle, which is to say a real intermediate image would arise a short distance downstream of the catadioptric arrangement 10, as already mentioned. By contrast, the point of intersection of the chief ray with the optical axis 2 upon exit from the catadioptric arrangement 10 is located upstream thereof, which is to say the chief ray diverges. In order to obtain a convergent chief ray, it is necessary to use positive refractive power on the image side of the catadioptric arrangement 10, at a position where the chief ray height is larger than the size of the image. However, this is only the case at a certain distance downstream of the catadioptric arrangement 10, with the marginal rays having already focused at this point.

[0130] A strong diverging refractive power is used directly downstream of the catadioptric arrangement 10, which is to say on the image side, to shift the focus of the marginal rays of the catadioptric arrangement 10 further in the direction of the image plane 6 and let the chief ray height increase quicker in the light direction, the strong diverging refractive power specifically being in the form of a lens unit with negative refractive power, which includes the diverging lenses 41, 42, and 43, which moves the intermediate image significantly further away from the catadioptric arrangement 10, in order then to be able to set the desired convergent chief ray angle using the lens 44 with positive refractive power or a corresponding lens group.

[0131] In the exemplary embodiment shown, the lens unit with the diverging effect includes three doubly aspherical lenses 41, 42, and 43 and the lens unit with a converging effect includes a converging, doubly aspherical lens 44.

[0132] The imaging scale of the optical arrangement shown, which may be an objective, is −1:1. The angles of the chief ray in the object space and image space are the same in terms of absolute value and only differ in terms of sign.

[0133] The exemplary embodiment shown in FIG. 11 differs from the exemplary embodiment shown in FIG. 10 in that the optical arrangement 1 in the form of an objective is designed for the observation of aqueous object spaces with an exemplary refractive index of n=1.334 (water). Accordingly, there is a magnifying imaging scale of −1.334:1. However, the geometric chief ray angles in the object and in the image are the same in terms of absolute value and differ in sign.

[0134] The exemplary embodiment shown in FIG. 12 builds on the exemplary embodiment shown in FIG. 10. However, in this case the catadioptric arrangement 10 includes a first optical component 11 and a second optical component 12, in a manner analogous to the exemplary embodiments of the first embodiment variant. This configuration is advantageous in that additional lens surfaces, in the form of the back side 16 of the second optical component 12 and the front side 13 of the first optical component 11, are available herewith as optical design means, in particular for beam shaping and for correcting aberrations.

[0135] Moreover, both the first optical component 11 and the second optical component 12 have at least one surface with a non-uniform surface description. By way of example, the radially outer region of the front side 15 of the second optical component 12 has a pronounced aspherical embodiment while the radially inner region of the front side 15 of the second optical component 12 has a pronounced concave embodiment when viewed from the outside. In the configuration shown, the back side 16 of the second optical component 12 is identified by a uniform surface description.

[0136] The first optical component 11 has a radially outer region 22 configured in slight meniscus form while the radially inner region 21 has a pronounced meniscus form, which is to say adopts the function of the divergently acting lens unit in comparison with the exemplary embodiment shown in FIG. 10. Outside of the catadioptric arrangement 10, the field lens group 40 merely consists of the converging lens 44 or a corresponding converging lens group in this example. This configuration has the advantage of enabling an overall very simple and compact arrangement which, in particular, requires only very few lens elements.

[0137] The exemplary embodiment shown in FIG. 13 differs from the above-described exemplary embodiment in that it is provided for an object space in or with aqueous solution, and consequently has an imaging scale of −1.334:1.

[0138] A third embodiment variant of the present disclosure is explained in more detail hereinafter on the basis of the exemplary embodiments shown schematically in FIG. 14 to 18. Here, the focus of the third embodiment variant is primarily that of effectively reducing the obscuration.

[0139] The optical arrangement 1 shown in FIG. 14 is embodied as a photographic objective, which is to say it serves to image objects situated at a distance. The shown photographic objective or the corresponding optical arrangement 1 has a focal length of 22 mm and is realized within an axial installation space of less than 6 mm. Hence, the telephoto factor is F=3,67. The axial installation space in this case indicates the distance from the front entrance surface, which is to say the front side 15 of the second optical component 12 in the present case, to the image plane 6. Two plane surfaces, between which the entire optical arrangement 1 can be accommodated, are considered for the distance. Thus, this does not only take into account the distance of the front surface vertex from the image plane, but the entire entrance surface.

[0140] Once again, the front side 15 of the second optical component 12 has no uniform surface description. Both the radially outer region 25 and the radially inner region 24 have an aspherical surface shape on the front side 15. However, the asphere equation for describing the radially outer region 25 of the front side 15 differs from the asphere equation for describing the radially inner region 24 of the front side 15. However, the surfaces are designed so that the two regions merge into one another, at least continuously but generally not in continuously differentiable fashion. This configuration is advantageous from a manufacturing point of view.

[0141] The surface description of the back side 14 of the first optical component 11 is not uniform either. The radially outer region 22, which is designed to be reflective, is convex when observed from the outside, which is to say the reflection from the inner side of the first optical component 11 occurs at a surface that is hollow or concave in the light direction. In the radially inner region 21, the back side 14 is predominantly shaped concavely. Both partial surface descriptions are aspherical and merge into one another continuously but not in continuously differentiable fashion.

[0142] In the beam path 17, the catadioptric arrangement 10 is adjoined by a lens group 40 which consists of a first diverging lens 41, for example consisting of polycarbonate, with substantially low refractive power and a second diverging lens 42 with high refractive power in this exemplary embodiment. In this case, it is especially the diverging lens 42 with high refractive power that acts as the field lens with negative refractive power required to reduce the obscuration. The obscuration is 40 percent in the present case. In this exemplary embodiment, the focal length of the optical arrangement 1 or objective has a value of f′=20 mm, which is to say an overall refractive power of φ=50 dpt. Furthermore, the field lens arrangement 40 has a vertex refractive power of 522 dpt.

[0143] The shown optical component parts and lenses typically consist predominantly of crown-type material, for example PMMA (PMMA—polymethyl methacrylate). The lens 41 is made of polycarbonate and has a doubly aspherical form. The use of a lens 41 with weak refractive power being made of the flint-type material polycarbonate moreover brings about a balanced chromatic correction of the overall design.

[0144] The diameter of the radially inner region 24 of the second optical component 12 has a slightly larger value than the inner region 21 of the first optical component 11. Both diameters are significantly smaller than the image diagonal, which is to say the diameter of the image plane 6. For quantification, it is possible to specify an (optically clear) diameter ratio between the region 24 and the diameter of the image diagonal, which ratio is at least smaller than 0.9, in particular smaller than 0.8 or 0.7. For example, this is not the case in FIGS. 4 to 9, where the diameter ratio is ˜1. The diameter ratio is 0.61 for the example shown in FIG. 14, 0.58 for the example shown in FIG. 15, 0.63 for the example shown in FIG. 16, 0.60 for the example shown in FIG. 17, and 0.62 for the example shown in FIG. 18. This once again reflects the fact that the diverging field lenses 41 or 42 or the field lens arrangement 40 lead/leads to a significant beam curtailment and consequently allows a minimal obscuration.

[0145] What is further advantageous for a small obscuration is that the radially outer region 22 of the first optical component 11, which is to say the reflective region, has a diameter that is as large as possible so that the diameter ratio between the radially outer, reflective region 22 and the radially inner, non-reflective region 20 becomes maximal, which in turn has an advantageous effect on the obscuration, which is to say reduces the latter. The reduction in the obscuration is achieved, inter alia, by the fact that the first optical surface on which the light is incident, which is to say the front side 15 of the second optical component 12, has a concave and hence diverging shape in the edge region. In particular, this increases the diameter of the beam at the location of the first optical component 11 and thus facilitates the realization of a small obscuration.

[0146] In contrast to the exemplary embodiment shown in FIG. 14, the first field lens 41 has been removed in the exemplary embodiment shown in FIG. 15. In the present case, the effect of the lens 41 was replaced by the first optical component 11 being made of polycarbonate and by the radially inner region 21 having a different surface description to the radially outer partial region 22, as a result of which the back side 14 no longer has a uniform surface description. However, the surface descriptions of the radially inner region and radially outer region on the back side 14 merge into one another continuously, albeit not in continuously differentiable fashion. Otherwise, the exemplary embodiment shown in FIG. 15 corresponds to the exemplary embodiment shown in FIG. 14.

[0147] The exemplary embodiments shown in FIGS. 14 and 15 relate to optical units with an infinite front focal length, as are typically used in the field of photographic optics in cellular telephones. The exemplary embodiments shown in FIGS. 16 to 18 relate to projection objectives which are based on the same principle, specifically of realizing a catadioptric arrangement with the smallest possible obscuration. In this case, the imaging scale is close to |β|=1:1, in order to enable microscopic applications. In this case, a large working distance free working distance (FWD) should be obtained during 1:1 imaging despite a very compact structure. Here, this free working distance should be twice as large as the quotient of installation length Ls or overall length or installation space L and the imaging scale β:

[00010]$FWD>2\frac{\mathrm{Ls}}{\beta }\mathrm{or}\mathrm{optionally}FWD>2\frac{L}{\beta }$

[0148] Here, L.sub.s denotes the installation length, which is to say the distance of the first lens vertex from the image plane. L denotes the overall length or the installation space, which is to say the spacing of two planes between which the entire optical unit can be “inserted”, which is to say the distance from the lens edge to the image plane, as measured parallel to the optical axis, in the present case.

[0149] In the case of the microscope objectives shown, the imaging scale is −0.8:1 and the overall length or the installation space L is approximately 6.5 mm, which is to say the working distance should be at least 15 mm.

[0150] In the exemplary embodiments shown in FIGS. 16 to 18, the working distance of the object is 25 mm in each case. The aforementioned condition for the working distance FWD is satisfied very well with the aforementioned imaging scale of −0.8:1 and an installation space L of 6.5 mm. Otherwise, the individual optical components and lenses as well as materials thereof and the sequence of surfaces of the exemplary embodiment shown in FIG. 16 correspond to those of the exemplary embodiment shown in FIG. 15. In contrast to the exemplary embodiment shown in FIG. 15, the obscuration is only 36 percent.

[0151] FIG. 17 shows an optical arrangement in the form of a microscope objective with an imaging scale of −0.8:1. The general structure is identical to that of the exemplary embodiment shown in FIG. 15. Here, too, the first of the two field lenses, which is to say the lens 41, was dispensed with and use was made instead of a first optical component 11 made of a flint material, for example polycarbonate, and the back side 14 of the first optical component 11 was designed as a non-uniformly defined surface such that the optical effect in the transmissive radially inner region 21 differs from the optical effect in the reflective radially outer region 22. Here, too, the two partial surface regions merge into one another continuously, but not in differentiable fashion. Once again, the obscuration is 36 percent.

[0152] In the exemplary embodiment shown in FIG. 18, the design degree of freedom of a non-uniformly defined back side 14 of the first optical component 11 was dispensed with, with the result that the optical arrangement 1 is now constructed from the catadioptric arrangement 10 with a non-uniformly defined front side 15, a uniformly defined back side 14 and a field lens 42 with negative refractive power. The obscuration is 38 percent in this case.

[0153] The features of the exemplary embodiments of the third embodiment variant advantageous for a low obscuration are compiled in the following tables. Here, L.sub.s denotes the installation length, which is to say the distance of the first lens vertex from the image plane. L denotes the overall length or the installation space, which is to say the spacing of two planes between which the entire optical unit can be “inserted”, which is to say the distance from the lens edge to the image plane, as measured parallel to the optical axis, in the present case. D.sub.2 is the optically clear diameter of the transmissive region on the back side of the first optical component 11. D.sub.1 is the diameter of the detector or its image diagonal or the diameter of the surface of the image plane in which an image representation is generated, or the diameter of the exit pupil. F.sub.FL′ is the paraxial refractive power of the field lens group with negative refractive power, and RH.sub.1 and RH.sub.2 are the best fit radii of the field lens with negative refractive power. F.sub.FLH′ is the best fit radius refractive power of the field lens with negative refractive power. N.sub.2*RVL.sub.2 is the meridional optical direction cosine of the chief ray prior to the exit from the first optical component 11. N.sub.i*RVL.sub.i is the optical direction cosine of the chief ray at the detector or at the image plane 6. Here, the optical direction cosine is understood to be the geometric direction cosine multiplied by the refractive index of the respectively considered medium.

TABLE-US-00001 TABLE 1 FIG. L.sub.S L F.sub.FL′ |L.sub.S/F.sub.FL′| |L/F.sub.FL′| 14 5.505 5.962 −1.914 2.876 3.115 15 5.195 5.205 −2.104 2.469 2.474 16 5.751 6.500 −1.956 2.940 3.323 17 5.559 6.155 −1.838 3.024 3.349 18 5.796 6.501 −1.884 3.076 3.451

TABLE-US-00002 FIG. D.sub.2 D.sub.i D.sub.2/D.sub.i 14 2.327 3.840 0.606 15 2.267 3.840 0.590 16 2.374 3.840 0.618 17 2.343 3.840 0.610 18 2.444 3.840 0.637

TABLE-US-00003 TABLE 3 FIG. RH.sub.1 RH.sub.2 F.sub.FLH′ 14 −1.361 −101.469 −2.805 15 −1.596 −20.052 −3.526 16 −1.383 −55.220 −2.884 17 −1.356 −12.076 −3.106 18 −1.444 13.622 −2.654

TABLE-US-00004 TABLE 4 FIG. N.sub.2*RVL.sub.2 N.sub.i*RVL.sub.i N.sub.i*RVL.sub.i/N.sub.2*RVL.sub.2 14 0.299 0.531 1.774 15 0.324 0.535 1.646 16 0.302 0.522 1.725 17 0.307 0.532 1.731 18 0.286 0.572 2.004

[0154] FIG. 19 schematically shows a device 50 according to the disclosure. The device 50 can be a microscope or a mobile device. The device 50 includes an above-described optical arrangement 1 according to the disclosure. It has the features and advantages already mentioned in this context. In particular, the optical arrangement 1 can be configured as an objective 51 and/or can contain an image capture apparatus, for example a camera.

[0155] It is understood that the foregoing description is that of the exemplary embodiments of the disclosure and that various changes and modifications may be made thereto without departing from the spirit and scope of the disclosure as defined in the appended claims.

LIST OF REFERENCE NUMERALS

[0156] 1 Optical arrangement [0157] 2 Center axis [0158] 3 Object side [0159] 4 Image side [0160] 5 Object/object plane [0161] 6 Image plane/detector [0162] 7 First converging lens [0163] 8 Second converging lens [0164] 9 Chief ray [0165] 10 Catadioptric arrangement [0166] 11 First, partly reflective optical component [0167] 12 Second, partly reflective optical component [0168] 13 Front side [0169] 14 Back side [0170] 15 Front side [0171] 16 Back side [0172] 17 Beam path [0173] 18 Entrance pupil/stop [0174] 19 Third optical component [0175] 21 Radially inner region [0176] 22 Radially outer region [0177] 23 Reflective coating [0178] 24 Radially inner region [0179] 25 Radially outer region [0180] 26 Reflective coating [0181] 27 Diverging lens [0182] 28 Plane parallel plate [0183] 29 Front side [0184] 30 Back side [0185] 31 First reflective optical surface, primary mirror [0186] 32 Second reflective optical surface, secondary mirror [0187] 33 Front side [0188] 34 Back side [0189] 35 Radially inner region [0190] 36 Radially outer region [0191] 37 Radially inner region [0192] 38 Radially outer region [0193] 40 Field lens group [0194] 41 Lens with negative refractive power, diverging lens [0195] 42 Lens with negative refractive power, diverging lens [0196] 43 Lens with negative refractive power, diverging lens [0197] 44 Lens with positive refractive power, converging lens [0198] 50 Device [0199] 51 Objective [0200] Ai Object [0201] A.sub.i′ Image representation [0202] D.sub.i Diameter of the exit pupil, diameter of the detector or its image diagonal [0203] d.sub.0 Beam diameter [0204] d.sub.1 Diameter of the entrance pupil [0205] d.sub.2 Diameter of the entrance pupil [0206] L.sub.s Distance from the vertex of the object side to the image plane [0207] L.sub.0 Distance from the entrance pupil to the image plane or to the detector [0208] h.sub.0 Height of the marginal ray R0 [0209] h.sub.1 Height of the light ray R1 [0210] R.sub.0 Marginal ray [0211] R.sub.1 Light ray [0212] rvl.sub.o Direction cosine of the marginal ray R0 [0213] rvl.sub.1 Direction cosine of the light ray R1 [0214] γ Chief ray angle [0215] γ′ Chief ray angle