OPTICAL ASSEMBLY FOR CHANGING THE DIRECTION OF LIGHT BEAMS WITH AT LEAST TWO MIRROR PARTS

Description

[0001] The invention relates to an optical assembly with two or more flat mirror parts, two of which can be adjusted to a predetermined angle relative to each other during or after assembly. An assembly of this type is known from DE 464 561 C.

[0002] To statically reflect a light beam twice in immediate succession within an optical system, reflection prisms are typically used, especially when a very precise angular position of the two reflecting surfaces relative to each other is essential. One example of this is a roof prism, which serves to invert the image and in which the image is formed simultaneously across both roof surfaces. The two roof surfaces must form an angle of exactly 90° to avoid a double image.

[0003] The optical effect of prisms is determined by their boundary surfaces and the relative position of the surfaces optically effective from the boundary surfaces. Optically effective surfaces are entrance and exit surfaces as well as reflection surfaces. Reflection prisms, where dispersion is not desired, are designed so that a beam of rays strikes an entrance surface and an exit surface perpendicularly and thus has no optical effect, at least for the axial ray of the beam. Between the entrance surface and the exit surface, the beam is reflected by two or more reflection surfaces. If the beam does not strike one of the reflection surfaces at an angle of total internal reflection, this surface can be mirrored from the outside to fully or partially reflect the beam. The reflection layers can therefore also be used as beam splitter layers.A prism basically has the advantage that the angular position of the reflection layers, which was set during the manufacture of the prism, is permanently maintained and the reflection prism requires only a small amount of space.

[0004] Disadvantages of reflective prisms include their complex manufacturing process, the resulting aberrations at the entrance and exit surfaces, their comparatively high weight, and the long glass path, which impedes high transmission. Furthermore, the refractive index of the glass must be very homogeneous, and a suitable glass material must be selected for the corresponding wavelength range.

[0005] There have therefore been repeated attempts to use assemblies formed by assembled mirror parts to change the direction of light rays.

[0006] DE 1 101 010 B describes a central mirror composed of three mirror parts. The angular position of the three mirror parts relative to each other depends on the precise grinding of the lateral contact surfaces of the mirror parts. It is therefore necessary to produce side surfaces on each mirror part with close angular tolerances in order to obtain a central mirror with reasonably close tolerances. The disadvantages here are the high manufacturing and testing effort, the high risk of rejects, and an unavoidable angular tolerance.

[0007] DE 30 19 629 C2 discloses a closely toleranced roof mirror that functions as a roof prism. The roof mirror is formed from two mirror parts that are brought into a closely toleranced angular position with the aid of a closely toleranced angle gauge and are joined together in this position by cement. The course of the cemented surface at right angles to the roof edge prevents changes in the roof edge angle due to shrinkage of the cement. The roof mirror therefore constantly maintains its angular position determined by the angle gauge. The disadvantage here is that tolerances of the mirror parts are ignored, which means that the angle that the mirror parts form with each other after assembly is subject to a large tolerance.

[0008] From the aforementioned DE 464 561 C, an image-inverting viewfinder system with three mirror parts arranged in a defined manner relative to one another, which fulfill the function of a pentaprism, is known. The two mirror parts, each forming a roof surface, are aligned perpendicular to one another in a housing part and are held together so as to form a roof edge. One of these two mirror parts is held in the housing part near the roof edge by an elastic means and rests at an end remote from the roof edge on an adjustment plate which can be raised and lowered via a screw. This allows this mirror part to be tilted about a pivot point in the elastic material, whereby the angle that the two mirror parts form with one another can be adjusted. The adjusted position is secured by lacquering at various securing points.

[0009] Compared to the use of a pentaprism, this arrangement has the advantage of being lighter and of avoiding the errors caused by a transmissive deflecting system compared to a reflective deflecting system.

[0010] The disadvantages are the comparatively high manufacturing and assembly costs and the non-guaranteed long-term stability of the adjustment position.

[0011] DE 44 32 086 A1 describes an optical assembly, in particular a retroreflector with an adjustment mechanism. It consists of at least two mirror parts (here, planar individual parts), wherein a side surface of the first mirror part is joined to a mirror surface (here, reaction surface) of the second mirror part in a specific relative position by cement. The two mirror surfaces of the two mirror parts thus form an edge and enclose a predetermined angle with each other, the vertex of which lies on the edge. In order to be able to adjust this angle, it is proposed that an adjustment gap be incorporated into a free side surface (the side surface of the first mirror part which, as an extension of the rear surface of the second mirror part, adjoins it), apparently running perpendicular to the side surface, and the depth of which approximately corresponds to the thickness of the second mirror part.Depending on the desired adjustment state of the angle, a wedge is pressed into the adjustment gap to a corresponding depth and fixed in a force-fitting manner. The depth of the adjustment gap equal to the thickness of the cemented second mirror part is a mandatory requirement in order to tilt the mirror surface of the first mirror part towards that of the second mirror part by spreading the adjustment gap apart by pressing in the wedge and thus reducing the angle. The other values ​​mentioned for the parameters of the adjustment gap and the wedge, such as the adjustment gap width, which corresponds to approximately a quarter of the thickness of the first mirror part, or the wedge angle of approximately 10', are of a rather advantageous nature, although they are stated in the description as having no alternative and are stated in the highest-ranking patent claim, which claims an adjustable assembly. An assembly according to the prior art is described in . Fig. 9a shown.

[0012] The absolute necessity of the depth of the adjustment gap equal to the thickness of the first mirror part is shown by the Fig. 9c explained. If the depth of the adjustment gap were smaller than the thickness of the first mirror part, a portion of the joining area between the two mirror parts (shown hatched), which is determined by the difference in depth and thickness, would act as a counterweight against deformation and thus tilting of the mirror surface. On the other hand, if the depth corresponds to the thickness, the first mirror part is deformed in such a way that the back side, and consequently the mirror surface of the first mirror part, is tilted around a pseudo-pivot point in the edge. Fig. 9b The directions of action of the partial forces are shown as they act on the wall surfaces of the adjustment gap, which has a rectangular cross-section in the stress-free state. While the partial force applied to the first mirror part is directed largely perpendicular to its rear side, the partial force applied to the second mirror part is directed largely parallel to the rear side. Accordingly, stresses acting in different directions arise in the mirror parts, and the angle adjustment is achieved solely by deforming one of the mirror parts.

[0013] It is the object of the invention to provide an optical assembly with at least two mirror parts which enclose a narrowly tolerated angle with each other in a long-term stable manner, in which the mirror parts are either stress-free or at least subject to approximately equal stress.

[0014] The problem is solved for an optical assembly with the features of claim 1. Advantageous embodiments are specified in the dependent claims.

[0015] The invention will be explained in more detail below using exemplary embodiments with the aid of drawings. These show: Fig. 1a a perspective view of a first basic variant of an optical assembly with two mirror parts with a gap body in an adjustment gap between a joining surface on the second mirror part and a mirror surface of the second mirror part, Fig. 1b a side view of the first basic variant according to Fig. 1a , Fig. 2a a perspective view of a second basic variant of an optical assembly with a wedge as a gap body in an adjustment gap in the form of a groove in the second mirror part, Fig. 2b a side view of the second basic variant according to Fig. 2a , Fig. 2c a representation of the force input into the second basic variant, wherein the line of action represents an angle bisector of the first angle, Fig. 3a a perspective representation of the second basic variant of an optical assembly with a cylinder rod as a gap body in an adjustment gap in the form of a groove in the second mirror part, Fig. 3b a side view of the second basic variant according to Fig. 3a , Fig. 4a a first embodiment of an optical assembly for both basic variants, with partially mirrored mirror surfaces, Fig. 4b a second embodiment of an optical assembly for both basic variants, with a special coating, Fig. 4c a third embodiment of an optical assembly for both basic variants with spherically curved mirror and rear surfaces, Fig. 4d a fourth embodiment of an optical assembly for both basic variants, with a freeform or aspherically curved rear surface, Fig. 5 a fifth embodiment, which is an alternative modification of the first to fourth embodiments, with three mirror parts which, in pairs, enclose an angle α of 90° with each other, Fig. 6 a sixth embodiment, which is an alternative modification of the first to fourth embodiments, with three mirror parts which, in pairs, enclose an angle α of 120° with each other, Fig.Fig. 7 shows a seventh embodiment, which is alternatively a modification of the first to fourth embodiments, with two mirror parts, each having a triangular mirror surface, Fig. 8 shows an eighth embodiment, which is alternatively a modification of the first to fourth embodiments, with two mirror parts, each having a semi-elliptical mirror surface, and Figs. 9a-9c are representations to explain the prior art.

[0016] The invention relates to an optical assembly, which, in all embodiments, leads to a change in the direction of light beams directed thereto. Furthermore, it can advantageously influence the light in other ways at the same time, which will be explained using exemplary embodiments.

[0017] The optical assembly consists of at least two mirror parts 1, 2, but depending on the number of desired changes of direction for a light beam, it can also comprise more mirror parts 1, 2, two of which together form a pair of mirror parts 0.

[0018] The mirror parts 1, 2 each represent a glass body with a mirror surface 1.1, 2.1, a rear surface 1.2, 2.2 parallel thereto and at least three side surfaces. Two of the mirror parts 1, 2 are arranged relative to one another in such a way that their mirror surfaces 1.1, 2.1 adjoin one another, enclosing a predetermined first angle α with one another and forming an edge 3 with a length l.

[0019] If the optical assembly comprises more than two mirror parts 1, 2, the mirror surface pairs formed by two of the mirror surfaces 1.1, 2.1 can each have a different value for the first angle α and / or the length l of the respectively formed edge 3. For each mirror surface pair, one of the two mirror parts 1, 2 forming the mirror surface pair has a flat side surface which represents a joining surface 1.3. The peripheral shape of the mirror surfaces 1.1, 2.1 can be adapted as desired to the beam cross-section of a light beam for which the optical assembly is intended, apart from a limitation due to a joining surface 1.3. For a typically round beam cross-section, the mirror surface 1.1, 2.1 will be rectangular, in particular square.

[0020] The optical assembly contains an adjustment gap 6 in which a gap body 4 is arranged, with which a first angle α, which the two mirror surfaces 1.1, 2.1 of each pair of mirror surfaces enclose with each other, was adjusted with a high accuracy up to the range of angular seconds during assembly of the optical assembly.

[0021] It is essential to the invention that the gap body 4 projects into the optical assembly at a depth t along a line of action 5 which intersects the edge 3.

[0022] The line of action 5 indicates the direction (splitting direction) in which the splitting body 4 was introduced into the optical assembly, more precisely into the mirror part pair 0, and runs through the splitting body 4.

[0023] The adjustment gap 6 can be formed either by a mirror surface and a side surface of the mirror parts 1, 2 forming a mirror part pair 0, or by a groove in one of the two mirror parts 1, 2. The deeper the gap body 4 is inserted into the adjustment gap 6 in the direction of the line of action 5, the larger the angle that the wall surfaces of the adjustment gap 6 form with each other. This change in angle is transferred to the first angle α. There are basically two basic variants for where the gap body 4 can be arranged in the optical assembly.

[0024] A first basic variant for an optical assembly is shown in the Fig. 1a und 1b shown using two mirror parts 1, 2. A side surface of the first mirror part 1 represents a joining surface 1.3, which encloses a second angle β with the mirror surface 1.1 of the first mirror part 1, which second angle β is less than 180° minus the first angle α. The joining surface 1.3 and the mirror surface 2.1 of the second of the mirror parts 2 enclose a third angle γ with each other and form an adjustment gap 6, in which the gap body 4 sits and against which the joining surface 1.3 and the mirror surface 2.1 of the second mirror part 2 bear. The first angle α is 90° here, for example. Accordingly, the second angle β is less than 90°, e.g. 88.5°, so that the third angle γ is 1.5°. To precisely adjust the first angle α, the joining surface 1.3 and the mirror surface 2.1 of the second mirror part 2 were placed together during assembly. By progressively inserting the gap body 4, which is advantageously a wedge here, between the joining surface 1.3 and the mirror surface 2.1, a growing wedge-shaped adjustment gap 6 was formed until the first angle α reached a predetermined value, here 90°, for example. After the wedge was finally fixed in place by filling the adjustment gap 6 with adhesive 7, the end of the wedge still protruding from the adjustment gap 6, shown as a dotted line in the drawings, was severed. If the optical assembly contains more than two mirror surfaces 1.1, 2.1, two mirror surfaces 1.1, 2.1 each form a mirror pair, which are mounted in the same way as the described mirror pair and are arranged relative to one another. The angles mentioned can have different or identical values ​​to those given for the first mirror pair.

[0025] A second basic variant for an assembly is in the Fig. 2a - 3b also shown as an example using two mirror parts 1, 2.

[0026] Here too, a side surface of the first mirror part 1 represents a joining surface 1.3. This joining surface 1.3 and the mirror surface 1.1 of the first mirror part 1 enclose a second angle β with each other, which is less than 180° minus the first angle α. The joining surface 1.3 and the mirror surface 2.1 of the second of the mirror parts 2 are advantageously joined together by diffusion welding, so that the two mirror surfaces 1.1, 2.1, before the gap body 4 was introduced into the optical assembly (indicated by dashed lines), enclose an angle α with each other that is slightly larger than the predetermined first angle α. In the second mirror part 2, a prefabricated groove with a trapezoidal or V-shaped cross-section over the length l, which runs parallel to the edge 3, is provided as an adjustment gap 6. The gap body 4 sits force-fitting in the groove.As the gap body 4 was inserted deeper and deeper, bending forces were introduced into the second mirror part 2 via the groove, which led to increasingly greater notch stresses in the groove and a bending of the first and second mirror parts 1, 2 towards each other. A wedge, shown in the . Fig. 2a und 2b , However, a cylinder rod is preferred, shown in the Fig. 3a und 3b ,for use. The gap body 4 extends at least over half, preferably approximately or completely over the length l of the edge 3. The gap body 4 was inserted into the groove until, due to the bending of the first and second mirror parts 1, 2, the mirror surface 2.1 of the second mirror part 2 and the mirror surface 1.1 of the first mirror part 1 were positioned at an angular distance of the predetermined first angle α from one another. Advantageously, the rear surface 2.2 of the second mirror part 2 has a bevel running orthogonally to the line of action 5, along which the excess portion of the gap body 4 protruding from the groove, shown as dotted lines in the drawings, was cut off after completion of assembly and adjustment. It is particularly advantageous if the line of action 5 represents an angle bisector of the first angle α. In Fig. 2c The force distribution is shown for this design. The force introduced via the wedge or another gap body 4, such as a cylindrical rod, by pressing it into the groove along the line of action 5 is transmitted in the same amount and in the same direction to the rear surfaces 1.2, 2.2 of the two mirror parts 1, 2. Because the two mirror parts 1, 2 have been joined together by diffusion welding, they act together like a monolithic component and the force input leads to equal tension and thus deformation of the two mirror parts 1, 2. The gap body 4 can also consist of two or more segments, which are inserted, for example, at the two ends of the groove or distributed across the groove. If these are inserted into the groove at different depths, not only the angular distance but also a pyramidal error of the optical assembly can be corrected.

[0027] Based on the alternative use of the two aforementioned basic variants, a variety of optical assemblies with the same functionality can be realized. These should primarily replace reflection prisms, but can also be designed to simultaneously split and influence the light beam, such as shaping or polarizing. Fig. 4a - 4d , 5 , 6 , 7 und 8 The designs shown in the sketches are optical assemblies assembled according to the first or second basic variant. In some of the figures, the path of the main ray of a light beam directed onto the optical assembly is indicated to illustrate the functionality of the respective design.

[0028] The Fig. 4a The first exemplary embodiment shown, for example, shows an optical assembly in which the two mirror surfaces 1.1, 2.1 are each partially mirrored. The first angle α is 90°. A portion of a light beam directed at an angle of incidence onto the mirror surface 1.1 of the first mirror part 1 is reflected back in the direction of incidence, as with a half-cube prism, while a second portion is transmitted through the mirror surface 1.1 of the first mirror part 1 and a third portion is transmitted through the mirror surface 2.1 of the second mirror part 2. By changing the angle of incidence, the angle that the two transmitted beam portions form with one another can be changed.

[0029] In the Fig. 4b In the second embodiment shown, the mirror surface 1.1 of the first mirror part 1 is provided with a partial mirror coating, and the mirror surface 2.1 of the second mirror part 2 is provided with a reflective phase or amplitude grating layer. In addition to a partial beam coupled out of the first mirror part 1, a beam component reflected at the second mirror part 2 is decomposed into a diffraction spectrum.

[0030] In the Fig. 4c In the third exemplary embodiment shown, the mirror surface 2.1 and the rear surface 2.2 of the second mirror part 2 are spherically curved in one direction, in addition to the partial mirroring of the mirror surface 2.1, representing cylindrical lens surfaces, whereby both a second beam component reflected by the second mirror part 2 and a third beam component transmitted therethrough are each focused into a linear beam distribution. A first beam component is coupled out by the partial mirroring of the mirror surface 1.1 of the first mirror part 1.

[0031] In an embodiment not shown in the drawings, the cylindrical lens surfaces according to the third embodiment are rotationally symmetrical spherical surfaces which each focus the beam components of an incident parallel light beam into a focal point.

[0032] In the Fig. 4d In the fourth embodiment shown, the rear surface 2.2 of the second mirror part 2 is designed as a free-form or spherical surface.

[0033] The above four embodiments could be supplemented by an unlimited number of further embodiments, with different numbers of mirror parts, different shapes of mirror parts, different first angles α, different functional coatings and different surface shapes of the mirror and rear surfaces.

[0034] For example, the Fig. 5 und Fig. 6 each a variant with three mirror surfaces, here in an arrangement that can replace a pentaprism, Fig. 7 a variant with two triangular mirror surfaces and Fig. 8A variant with two semi-elliptical mirror surfaces. The variant with the semi-elliptical mirror surfaces in combination with a first angle α of 90° and fully mirrored mirror surfaces 1.1, 2.1 of the first and second mirror parts 1, 2 is a particularly advantageous design for replacing a roof prism, with minimal weight, since the two mirror surfaces 1.1, 2.1, projected into a plane, form a circle that can be adjusted to the diameter of the light beam, which is reflected in itself here.

[0035] Particularly when using the optical assembly in the function of a roof prism, it is advantageous if the joining surface 1.3 and the mirror surface 2.1 of the second mirror part 2 are directly diffusion-welded without adhesive. The formation of double images due to the adhesive possibly applied along the edge 3 can thus be reliably prevented by a sharp edge 3.

[0036] Optical assemblies according to the invention are advantageous for a wide range of applications in measurement systems, material processing systems that operate with optical beams, and optical imaging systems such as binoculars, projection devices, and cameras. They offer a compact, comparatively cost-effective alternative to a variety of conventional optical components or assemblies. List of reference symbols

[0037] 0Mirror part pair 1First mirror part 1.1Mirror surface of the first mirror part 1 1.2Rear surface of the first mirror part 1 1.3Joining surface 2Second mirror part 2.1Mirror surface of the second mirror part 2 2.2Rear surface of the second mirror part 2 3Edge 4Gap body 5Line of action 6Adjustment gap 7Adhesive αfirst angle βsecond angle γthird angle llength tdepth

Claims

1. An optical assembly for changing the direction of light beams with at least two mirror sections (1, 2), wherein the mirror sections (1, 2) are each formed by a glass body having a mirror surface (1.1, 2.1), a rear surface (1.2, 2.2) parallel thereto and at least three lateral surfaces and are arranged relative to each other in such a way that in each case the mirror surfaces (1.1, 2.1) of two of the mirror sections (1, 2), which form a pair of mirror sections (0), adjoin each other, enclosing a predetermined first angle (α) with each other and forming an edge (3) with a length (I), and an adjustment gap (6) is present in the pair of mirror sections (0), in which a gap body (4) is inserted along a line of action (5) extending through the gap body (4) in a gap direction, protruding into the adjustment gap (6) to a depth (t), the depth (t) being co-determining for the first angle (α), characterized in that the line of action (5) intersects the edge (3).

2. The optical assembly according to claim 1, characterized in that one of the lateral surfaces of the first of the mirror sections (1) forming a pair of mirror sections (0) constitutes a joining surface (1.3), and the joining surface (1.3) and the mirror surface (1.1) of the first mirror section (1) enclose a second angle (β) with each other which is smaller than 180° minus the first angle (α), and the joining surface (1.3) and the mirror surface (2.1) of the second of the mirror sections (2), enclosing a third angle (γ) with each other, form the adjustment gap (6) which is filled with adhesive (7) and in which the gap body (4) is seated in a material-locking manner against the joining surface (1.3) and the mirror surface (2.1) of the second mirror section (2).

3. The optical assembly according to claim 1, characterized in that one of the lateral surfaces of the first of the mirror sections (1) forming a pair of mirror sections (0) constitutes a joining surface (1.3) and the joining surface (1.3) and the mirror surface (1.1) of the first mirror section (1) enclose a second angle (β) with each other, which is less than 180° minus the first angle (α), and the joining surface (1.3) and the mirror surface (2.1) of the second of the mirror sections (2) are connected to each other in a material-locking manner, and in the second mirror section (2) the adjustment gap (6) is present with a rectangular, trapezoidal or v-shaped cross-section over the length (I), in which the gap body (4) is seated in a force-locking manner.

4. The optical assembly according to claim 2 or 3, characterized in that the gap body (4) is a wedge or a cylindrical rod.

5. The optical assembly according to claim 4, characterized in that the wedge or the cylindrical rod extends over at least half of the length (l).

6. The optical assembly according to claim 2 or 3, characterized in that the line of action (5) represents a bisector of the first angle (α).

7. The optical assembly according to claim 6, characterized in that the rear surface (2.2) of the second mirror section (2) has a chamfer running orthogonally to the line of action (5).

8. The optical assembly according to claim 1, characterized in that the rear surface (1.2) of the first mirror section (1) and / or the rear surface (2.2) of the second mirror section (2) is mirror-coated or partially mirror-coated or is provided with other functional coatings.

9. The optical assembly according to claim 1, characterized in that the rear surface (1.2) of the first mirror section (1) and / or the rear surface (2.2) of the second mirror section (2) has a curved surface shape.

10. The optical assembly according to claim 3, characterized in that the joining surface (1.3) and the mirror surface (2.1) of the second mirror section (2) are diffusion-bonded with each other.

11. The optical assembly according to claim 3, characterized in that the gap body (4) consists of two segments, each of which is inserted at one of the two ends of the adjustment gap (6).

12. The optical assembly according to claim 3, characterized in that the gap body (4) consists of at least three segments which are distributed over the adjustment gap (6), and at least two of the segments are located at different depths.