Optical measuring device and multi-mirror

Abstract

To provide a device capable of reducing a structure size and making quality of a result independent of a measuring direction.SOLUTION: There is provided a multiple mirror (10) for multiplying a single incoming wavefront (12) of electromagnetic radiation (11) into a plurality of outgoing wavefronts (14). The multiple mirror (10) includes: at least one first mirror (16) on which an incident wave front (12) first impinges; and a second mirror (18) on which the wave front is finally reflected, where these mirror surfaces are overlapped in a moving direction of the first wave front (12). The first mirror (16) is partially transparent to the electromagnetic radiation (11) and the second mirror (18) is fully reflective.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a multi-mirror for multiplying an incident wavefront according to the preamble of claim 1. The present invention further relates to an apparatus for optically measuring a surface according to the preamble of claim 6.

Background Art

[0002] Methods for measuring the phase of radiation (especially optical radiation), and apparatuses for measuring the phase of radiation (especially optical radiation) are known from German Patent Application Publication No. 198 56 400 (B4) and German Patent Application Publication No. 010 30 059 (B1). In the case of this known apparatus, a body is irradiated with coherent radiation of a predetermined frequency. The body may have a diffuse reflection surface. The radiation reflected by the body, or the radiation passing through the body or a transparent medium, is projected by an imaging optical system onto an image plane where the sensor is located. The sensor is preferably a surface sensor. The surface sensor may be part of a framing camera equipped with a corresponding lens optical system.

[0003] The known structure is composed of multiple parts and takes up space. This structure is large and includes a large number of components and lenses. Therefore, the known structure is expensive and complex. Furthermore, in the known structure, the shadow of the diagram is thick and only a narrow area can be measured. Furthermore, the image quality depends on the measurement direction.

Summary of the Invention

Problems to be Solved by the Invention

[0004] One object underlying the present invention is to create an apparatus that reduces the structural size and at the same time makes the quality of the results independent of the measurement direction.

Means for Solving the Problems

[0005] According to the present invention, this object is achieved by the features of the independent claims. The dependent claims describe refinements and alternative forms of the invention.

[0006] We propose a multi-mirror system. This multiplies the incident wavefront of electromagnetic radiation, causing multiple wavefronts to be emitted from the multi-mirror after the radiation is reflected. Electromagnetic radiation propagates in wave form, and the wavefront of each wave is oriented in the direction of propagation. The wavefronts are phase-shifted relative to each other. The multi-mirror system comprises at least one first mirror to which the incident wavefront first strikes, and a second mirror to which the wavefront is finally reflected. These mirrors overlap in the direction in which the first wavefront is moving. To ensure that the wavefront reaches the second mirror regardless of the overlap in the direction of propagation of the incident radiation, the first mirror is partially transparent to electromagnetic radiation, while the second mirror is fully reflective. In this way, a portion of the incident electromagnetic radiation is reflected by the first mirror, and the remaining portion propagates to the second mirror. There, the remaining radiation is also reflected, but with a time delay compared to the first reflection. This time delay causes a phase shift between the two portions of the reflected radiation. For example, when multiple multi-mirrors are combined, their phase shifts can be added together and used for interferometry applications. A sandwich-like arrangement of multi-mirrors allows for a very compact design, making multi-mirrors ideally suited for use in portable measuring devices (especially outside the laboratory). Multi-mirrors may preferably be used in shearography equipment.

[0007] To enable particularly efficient detection of the contour of the object being measured, at least one of the mirrors may be capable of polarizing electromagnetic radiation. For this purpose, it is preferable that the first and second mirrors can polarize the radiation in different directions, and these different directions may preferably be aligned to be orthogonal to each other. For example, when a beam with mixed polarization strikes a multi-mirror, a portion of the radiation having a uniform polarization direction can be polarized by the first mirror, while a second portion with a different polarization can pass through and reach the second mirror. The second portion can be reflected by the second mirror. The second mirror may be a simple non-polarizing mirror. Alternatively, the second mirror may have a polarizing effect, particularly in a direction orthogonal to the first mirror. Finally, in either case, two beams of different polarizations emerge from the multi-mirror. When one or more multi-mirrors are used, the emitted beams can overlap, and beams with the same polarization interfere with each other. When a single multi-mirror system is used, one of the two polarized wavefronts (reflected by the multi-mirror) interferes with a similarly polarized portion of a simple wavefront reflected by a simple mirror. The resulting image can be evaluated in relation to the composition of the object being measured.

[0008] Advantageously, at least one of the mirrors may be tilted relative to at least one other mirror. The distance between the mirror surfaces of these mirrors may be changed. The distance between the mirror surfaces may be kept constant in terms of position and / or time, or may be changed. Radiation is directly reflected by the mirror surfaces. Because this distance causes a phase shift, accurate measurements can be performed by using an apparatus with such multi-mirrors. When using one or more multi-mirrors, the image produced by interference may be affected by the tilt. When one multi-mirror is used, one of the two polarized wavefronts (reflected by the multi-mirror) interferes with a similarly polarized portion of a simple wavefront reflected by a simple mirror. These may also be shifted relative to each other in the image plane.

[0009] Mirrors are preferably designed to be flat. Such surface mirrors may be tilted relative to each other, resulting in a certain angle between them. Consequently, the angles of incidence and reflection of electromagnetic radiation may be offset between the first and second mirrors. This makes it possible to adjust the phase shift between the reflected wavefronts.

[0010] The mirrors are advantageously adjustable to each other in a simple manner, such that the first mirror is rotatable around a pivot axis, which is located, for example, in the frame of the mirror holder of these mirrors. The pivot axis may, for example, extend through the mirror surface, or may be located in front of or behind the mirror surface. The mirror preferably rotates away from a position parallel to the second mirror until it forms a desired angle with respect to the second mirror. Another pivot axis of such type may be mounted on the second mirror. Both mirrors may have such a pivot axis, or only one of the two mirrors may have such a pivot axis. For example, the first or second mirror may have a pivot axis.

[0011] An apparatus for performing optical measurements of a surface, having a preferably coherent light source (e.g., a laser) that emits an electromagnetic beam, may include at least one beam splitter. The beam splitter may be a two-part composite prism made of a material transparent to radiation. Specifically, the apparatus is an interferometer, which measures the surface by interferometry. To achieve a compact design and at the same time ensure maximum measurement accuracy even under harsh environmental conditions, at least one multi-mirror, with at least two mirror surfaces spaced apart from each other, is positioned in front of and / or behind the beam splitter in the direction of electromagnetic beam propagation. Such an apparatus is ideal for use in environments exposed to vibration. Furthermore, such an apparatus is largely unaffected by temperature and hygroscopic fluctuations.

[0012] To enhance this device, at least one diaphragm may be provided between the multi-mirror and the beam splitter. This further improves measurement accuracy. Furthermore, the diaphragm can be advantageously used to enable spatial phase shifting.

[0013] This device, which includes two beam splitters, two shutters, and two multi-mirrors, can achieve improved measurement accuracy. In this way, by passing light reflected from the surface of the object to be measured through such a device, it is possible to analyze that light using interferometry.

[0014] When using these multi-mirrors, the mirror surfaces with respect to electromagnetic radiation may be partially transparent. Specifically, at least one of the multi-mirrors includes a mirror that can be tilted relative to another mirror. The wavefront that strikes the multi-mirror is then split into two outgoing wavefronts, which are phase-shifted relative to each other. It is particularly preferable that the two multi-mirrors include a tiltable mirror.

[0015] A favorable development configuration includes at least one diaphragm having an aperture with a polarizing filter. The polarizing filter may be used to filter the reflected beam and to remove disruptive, irregular polarization.

[0016] Such modified beams are particularly suitable for interferometric measurements. Here, optimal results are obtained by having at least one diaphragm with two apertures, each aperture having a polarizing filter, and these filters preferably being aligned orthogonally to each other. Thus, two beams amplified by the multi-mirror may each pass through one aperture and undergo corresponding filtering. Each beam, after passing through filters aligned orthogonally to each other, has the polarization corresponding to the respective filter.

[0017] As an addition to or alternative to a polarizing filter, at least one diaphragm aperture may include a frequency filter, allowing only specific wavelengths to pass through the diaphragm.

[0018] The diaphragm may be designed as a grating diaphragm so that the instrument ensures optimal measurement in all spatial directions of the sample. Preferably, the grating diaphragm has aperture slit widths specified by two dimensions. By limiting the slit width on the diaphragm surface, the beam geometry can influence the two dimensions of the measured radiation.

[0019] Color cameras are particularly advantageous for analyzing various wavelengths. A color camera records electromagnetic radiation that has passed through at least one multi-mirror. Color cameras are capable of distinguishing between various wavelengths.

[0020] In one embodiment, the device includes a beam splitter, which is positioned in the propagation direction to be the first to be struck by electromagnetic radiation. As soon as the beam enters the device, it enters the beam splitter. The beam is then split within the beam splitter and guided to a movable mirror in the first propagation direction. The remaining beam of the split beam is guided to a fixed mirror in the second propagation direction. A diaphragm is positioned between the beam splitter and each of the two mirrors. Each split beam passes through each diaphragm at least twice and is merged again in the beam splitter. A virtual double slit is visible from the camera's perspective. This simple configuration makes it possible to create a robust, space-saving device that ensures a high degree of portability.

[0021] According to another development form, the present device includes another second beam splitter, a mirror, and a movable mirror, and the two beam splitters are arranged so as to be aligned on each other's diagonal lines. Virtual diagonal lines may be drawn passing through some corners of each beam splitter, and one mirror is arranged on each of the two sides of the diagonal arrangement of the beam splitters. The mirrors are arranged substantially parallel to the virtual diagonal lines passing through the beam splitters. One diaphragm is arranged between the beam splitter into which the beam enters second, that is, the beam splitter into which the partial beam from the first beam splitter enters, and the mirror. The diaphragm is substantially parallel to the surface of the beam splitter into which the beam reflected by the mirror enters. Of course, the diaphragm may be arranged at any location on the beam paths of the two beam splitters, in front of or behind the mirror.

[0022] Of course, as described so far and further described below, each feature can be used not only in the form of the explicitly stated combination, but also in other combination forms. The scope of the present invention is defined only by the claims.

[0023] Hereinafter, based on an exemplary embodiment, the present invention will be described in more detail with reference to the related drawings.

Brief Description of the Drawings

[0024] [Figure 1] Shows a multi-mirror with various outgoing beams. [Figure 2] Shows a device for performing optical measurement of a surface using a multi-mirror. [Figure 3] Shows an embodiment having a beam splitter, a fixed mirror, and a movable mirror. [Figure 4] Shows an embodiment having two beam splitters, a fixed mirror, and a movable mirror.

Modes for Carrying Out the Invention

[0025] Figure 1 shows a multi - mirror 10. This reflects electromagnetic radiation 11. The radiation 11 may be composed of coherent waves, which is similar to, for example, a laser. The multi - mirror 10 multiplies the incident wavefront 12 of the radiation 11, and as a result, a plurality of wavefronts 14 emerge from the multi - mirror 10 after reflection. The wavefronts are multiplied by two mirrors 16, 18, which are positioned parallel to each other and aligned so as to overlap each other in the propagation direction of the incident and reflected radiation 11. Reflection occurs on the mirror surfaces of the mirrors 16, 18. The mirrors 16, 18 are also spaced apart from each other in the propagation direction. Further, the first mirror 16 that the radiation 11 hits in the propagation direction is partially transparent to the electromagnetic radiation 11, while the second mirror 18 is completely reflective.

[0026] Now, when the incident wavefront 12 hits the first mirror 16, a part of it is reflected and sent back. Here, the incident angle coincides with the reflection angle with respect to the mirror surface. The remaining part is reflected by the mirror surface of the second mirror 18. Since the mirrors 16, 18 are spaced apart from each other, a certain time elapses between the first reflection and the second reflection. Therefore, the reflection at the first mirror 16 occurs earlier than the reflection at the second mirror 18. As a result, a phase shift occurs between the two outgoing wavefronts 14 from the first and second reflections.

[0027] The incident beam 11 is polarized in various directions. The mirrors 16, 18 may be designed such that the reflected radiation is polarized in only one direction. The two mirrors 16, 18 can polarize the radiation 11 in two directions perpendicular to each other. Each radiation 11 reflected by each of the mirrors 16, 18 is polarized in only one direction. Alternatively, for example, only the first mirror 16 may have a polarization effect, and the reflected part of the radiation 11 has uniform polarization. The remaining components of the radiation 11 proceed to the second mirror 18 and have orthogonal polarization. This second component may be reflected by the second mirror 18, and the second mirror 18 has no polarization characteristics. Nevertheless, the second component emerges from the multi - mirror 10 in a polarized state.

[0028] Figure 2 shows a device 100 for performing optical measurements of a surface, which includes two multi-mirrors 10, two beam splitters 102, and two diaphragms 104. The incident beam 11 is generated by irradiating the surface to be measured with coherent light. The coherent light may be, for example, a laser. When one or two multi-mirrors 10 are used, the phase-shifted wavefronts 14 emitted from each multi-mirror 10 are added together, and the radiation reflected by the mirrors 16 and 18 is... 14 These can interfere with each other. When a single multi-mirror is used, one of the two polarized wavefronts (reflected by the multi-mirror) interferes with a similarly polarized portion of the simple wavefront reflected by the simple mirror.

[0029] The radiation 11 reflected from the surface to be measured first enters the beam splitter 102. The beam splitter 102 may have a rectangular cross-section, and the incident beam 11 strikes the flat surface of the beam splitter 102, which in particular does not face any of the multi-mirrors 10. The beam 11 enters the first beam splitter 102, and two further beams 12 After being split, each of those wavefronts 12 strikes a multi-mirror 10, and the beam 12 The waves are then doubled again by the multi-mirrors 10. The wavefronts 14 emerging from each multi-mirror 10 are directed towards the second beam splitter 102. Each doubled and phase-shifted wavefront 14 passes through the diaphragm 104. Each diaphragm 104 is located on the flat surface of the second beam splitter 102. Alternatively, the diaphragm 104 may be located at any point on the respective beam paths between the first beam splitter 102 and the second beam splitter 102. At the second beam splitter 102, the phase-shifted outgoing beam arriving from the multi-mirrors 10 is directed towards the second beam splitter 102. 14 The beam is doubled again, and two wavefronts 15, each with the same phase, are directed towards the camera. The beams from the two multi-mirrors 10 are merged and split into two beams, each exiting from one side of the beam splitter 102. 14During merging, the elements interfere with each other, forming an interference pattern, which can be spectrally decomposed, for example, by Fourier analysis.

[0030] The two beam splitters 102 are positioned in a diagonal row with respect to the beam paths entering and exiting the multi-mirror 10. The multi-mirror 10 is located approximately between the beam splitters 102, to the left and to the right of the beam splitters 102. The two diaphragms 104 are located on the flat surface of the second beam splitter 102 and face the first beam splitter 102. Alternatively, the diaphragms 104 may be located at any point on the respective beam paths between the first and second beam splitters 102. The two diaphragms 104 are approximately perpendicular to each other. Alternatively, these diaphragms 104 may be positioned at angles that are not perpendicular to each other.

[0031] Each multi-mirror 10 includes two mirrors 16 and 18, with one of each mirror 16 or 18 having a rotation axis. For example, the first mirror 16 and / or the second mirror 18 may have rotation axes. One multi-mirror 10 may have a rotatable first mirror 16, and the other multi-mirror 10 may have a rotatable second mirror. The rotation axes may be aligned perpendicular to each other. The rotation of the mirrors 16 and 18 amplifies the beam. 14 It may be used to generate a phase shift. The phase shift depends on the angle 19 set between the two mirrors 16, 18 by rotation. The displacement of the mirrors is radiated 12 This can also cause shearing. The interference images of the polarized beams from the first and second mirrors 16 and 18 of the two multi-mirrors 10 may be shifted relative to each other by rotation. The axis of rotation may be mounted, for example, on the frame of the multi-mirrors 10.

[0032] After passing through the second beam splitter 102, the single-slit diaphragm 104 appears as a virtual double-slit diaphragm on the exit plane of the second beam splitter 102. This is because the two phase-shifted beams from each multi-mirror 10 are merged again after passing through their respective diaphragms 104. This double-slit spacing requires a spatial carrier frequency corresponding to the phase shift in space. Therefore, the carrier frequency is decoupled from the rotational positions of mirrors 16 and 18.

[0033] Mirrors 16 and 18 emit 12 The light is polarized in different directions depending on the reflection. For example, a partially transparent first mirror 16 emits light with a specific polarization. 12 It is possible to reflect only certain radiation, thereby allowing it to pass through. 12 It is reflected by the second mirror 18. In this situation, radiation 12 The reflected beams can be polarized in the same direction by the two first mirrors 16. 14 They can interfere with each other. Similarly, the beam from the second mirror... 14 These can also be polarized in the same direction. Therefore, they can also interfere with each other. In contrast, the beam from the first mirror 14 The first mirror cannot interfere with the beam 14 from the second mirror. This is because their polarization directions are different. Here, if the first polarizing mirror 16 of one multi-mirror 10 is tilted relative to the first polarizing mirror 16 of the other multi-mirror 10, the reflected beam 14 Interference images are generated between them. These images may be understood as sheared images. For example, they may be sheared horizontally, thereby enabling shearography measurements. Separately, the second mirror 18 of one multi-mirror 10 may be tilted toward the second mirror 18 of the other multi-mirror 10, thereby reducing the reflected beam 14 Another sheared image is generated due to the interference between the two images. The shearing may be performed, for example, in the vertical direction.

[0034] Thus, a horizontally sheared wavefront 14 and its associated reference wavefront, as well as a vertically sheared wavefront and its associated reference wavefront, are generated by the two multi-mirrors 10. Consequently, the carrier frequencies of each wavefront, polarized to allow interference in both the horizontal and vertical directions, are generated by the use of the diaphragm 104. As a result, the spectrum is separated in Fourier space.

[0035] Beams reflected from the first and second mirrors 16 and 18 14 Both images generated by the interference between the pair are captured by the camera. To evaluate the two sheared images separately, their polarization may be used as a criterion for separation. This can be achieved, for example, by using different spatial carrier frequencies depending on the polarization. For this purpose, the two diaphragms 104 may have polarization-specific apertures 106. The width of the apertures 106 of the diaphragms 104 determines the frequency width of the images proportionally generated by the interferometry in the Fourier analysis. The apertures 106 may include polarization filters.

[0036] As an addition to or alternative to this, aperture 106 emits a specific wavelength. 14 A frequency filter may be provided that allows only certain wavelengths to pass through. Filtering specific wavelengths improves measurement accuracy. This is because, for example, the aperture size can be adjusted to match only one wavelength. This avoids image errors. Using a color camera makes it possible to analyze filtered interference images from various wavelengths. For example, a frequency filter can be generated using a color filter.

[0037] Figure 3 shows a device 100 including a beam splitter 102, which is positioned in the propagation direction of the electromagnetic beam 11, and the beam 11 first enters the beam splitter 102. As soon as the beam 11 enters the device, it proceeds into the beam splitter 102 and is split within the beam splitter 102. A portion of the beam 11 is guided to a movable mirror 6 in a first propagation direction 1. The remaining beam of the split beam 11 is guided to a fixed-position mirror 5 in a second propagation direction 2. A diaphragm 104 is positioned between the beam splitter 102 and each of the two mirrors 6 and 5. Each portion of the beam obtained through the beam splitter 102 passes through each diaphragm 104 at least twice. That is, the portion of the beam passes through the diaphragm 104 once before being reflected by each mirror 6 and 5, and once after being reflected. These portion beams are merged again in the beam splitter 102 and directed towards the camera. From the camera's perspective, a virtual double slit 4 is visible.

[0038] Figure 4 discloses a further development configuration including a second beam splitter 102. Mirrors 5 and 6 are also part of the device 100, and the two beam splitters 102 are arranged diagonally opposite each other. A virtual diagonal 3 may be provided, passing through some corners of each beam splitter, thereby aligning some corners of each beam splitter 102 with respect to each other. One of the mirrors 6 or 5 is positioned on each of the two sides of the diagonal arrangement of the beam splitters 102. Mirrors 6 and 5 are positioned approximately parallel to the virtual diagonal 3 passing through the beam splitters 102. The directional mirror 6 may deviate from the parallel arrangement by an adjustment angle, but is reset to the parallel position. A diaphragm 104 is positioned between the beam splitter 102 into which the beam 11 enters second, i.e., the beam splitter 102 into which the partial beam from the first beam splitter 102 enters, and the mirrors 5 and 6, respectively. The diaphragm 104 is approximately parallel to the surface of the beam splitter 102 into which the beam 11 reflected by the mirrors 5 and 6 enters. [Note 1] A multi-mirror that multiplies an incident wavefront (12) of electromagnetic radiation (11) to form a plurality of outgoing wavefronts (14), comprising at least one first mirror (16) to which the incident wavefront (12) first strikes, and a second mirror (18) to which the wavefront is last reflected, wherein the mirrors (16, 18) overlap in the direction in which the first wavefront (12) moves, the first mirror (16) is partially transparent to the electromagnetic radiation (11), and the second mirror (18) is fully reflective. [Note 2] The multi-mirror according to Appendix 1, characterized in that at least one of the mirrors (16, 18) is capable of tilting with respect to at least one other mirror (18, 16). [Note 3] The multi-mirror according to Appendix 1 or 2, characterized in that the mirrors (16, 18) are flat and can be tilted relative to each other so as to straddle an angle (19). [Note 4] The multi-mirror according to any one of the appendices 1 to 3, characterized in that the first and / or second mirrors (16, 18) are rotatable about a pivot axis (20), and the pivot axis (20) is mounted in particular to the mounting frame of the mirrors (16, 18). [Note 5] A multi-mirror according to any one of the mirrors (16, 18) wherein at least one of the mirrors polarizes the electromagnetic radiation, and the first mirror (16) preferably reflects radiation of a specific polarization and transmits radiation of another polarization (preferably orthogonal to the specific polarization). [Note 6] An apparatus for performing optical measurements of a surface by interferometry, comprising a coherent light source that emits an electromagnetic beam (11) and at least one beam splitter (102), characterized in that at least one multi-mirror (10), which includes at least two mirror surfaces spaced apart from each other as described in any one of appendices 1 to 5, is positioned in front of and / or behind the beam splitter (102) in the propagation direction of the electromagnetic beam (12). [Note 7] The apparatus according to Appendix 6, comprising at least one diaphragm (104), wherein the at least one diaphragm (104) is positioned between the multi-mirror (10) and the beam splitter (102). [Note 8] The apparatus according to Appendix 6 or 7, characterized by comprising at least two beam splitters (102), at least two diaphragms (104), and at least one multi-mirror (10). [Note 9] The apparatus according to any one of the appendices 6 to 8, wherein the multi-mirror (10) includes at least one mirror (16, 18), the at least one mirror (16, 18) having a mirror surface and being partially transparent to electromagnetic radiation. [Note 10] The apparatus according to any one of the appendices 6 to 9, characterized in that in at least one of the multi-mirrors (10), mirror (16, 18) is capable of tilting with respect to another mirror (18, 16), thereby dividing the wavefront (12) that strikes the multi-mirror (10) into two outgoing wavefronts (14) that are phase-shifted with respect to each other. [Note 11] The apparatus according to any one of the appendices 6 to 10, characterized in that at least one diaphragm (104) has an aperture (106) including a polarizing filter. [Note 12] The apparatus according to any one of appendices 6 to 11, characterized in that at least one diaphragm (104) has at least two apertures, each of the at least two apertures has a polarizing filter, and the polarizing filters are preferably arranged orthogonally to each other. [Note 13] The apparatus according to any one of the appendices 6 to 12, characterized in that at least one diaphragm (104) has an aperture (106) having a frequency filter, thereby allowing only specific wavelengths to pass through the diaphragm (104). [Note 14] The apparatus according to any one of the appendices 6 to 13, wherein the diaphragm (104) is designed as a grating diaphragm and preferably has two specific slit widths of the aperture (106), the slit widths being particularly the same in dimension. [Note 15] The apparatus according to any one of the appendices 6 to 14, characterized in that the camera that records the electromagnetic radiation (11) that has passed through the at least one multi-mirror (10) is specifically designed as a color camera. [Note 16] The apparatus according to any one of the appendices 6 to 15, characterized in that a movable mirror (6) is positioned in the first propagation direction (1) of the beam (11) split by a beam splitter (102), a fixed-position mirror (5) is positioned in the second propagation direction (2), a diaphragm (104) is positioned between the beam splitter (102) and each of the mirrors (5, 6), the beam (11) passes through each diaphragm (104) at least twice, the beam (11) is merged again in the beam splitter (102), and a virtual double slit (4) is visible from the direction of the camera. [Note 17] The apparatus according to any one of the appendices 6 to 16, comprising two beam splitters (102), the beam splitters (102) being arranged diagonally opposite each other, a fixed mirror (5) being positioned on one of the two sides of the diagonal arrangement, a movable mirror (6) being positioned on the other side of the beam splitters (102) diagonally, and a shutter (104) being positioned between at least one beam splitter (102) and each of the mirrors (5, 6). [Note 18] The apparatus according to any one of the appendices 6 to 17, characterized in that the fixed mirror (5) and the movable mirror (6) are aligned substantially parallel to a virtual diagonal line passing through at least two beam splitters (102).

[0039] Reference Code List 1. First propagation direction 2. Second propagation direction 3 Diagonals 4 Virtual double slit 5 Fixed mirror 6. Movable Mirror 10 Multi-Mirror 11 Electromagnetic radiation 12 Incident wavefront 14. Outgoing wavefront 15 Wavefront facing the camera 16 The First Mirror 18 The Second Mirror 19 angle 20 Rotation axis 100 devices 102 Beam Splitter 104 Diaphragm 106 Aperture

Claims

1. An apparatus for performing optical measurements of a surface using interferometry, A coherent light source that emits an electromagnetic beam (11), Two beam splitters (102), Diaphragm (104) and, The multi-mirror (10) includes two mirrors spaced apart from each other, comprising a first mirror (16) to which the incident beam (11) first strikes, and a second mirror (18) to which the beam (11) is last reflected, wherein the mirrors (16, 18) are superimposed in the direction of motion of the first wavefront (12), the first mirror (16) is partially transparent to the electromagnetic beam (11), and the second mirror (18) is fully reflective, As a result, The beam splitter (102) and the multi-mirror (10) are arranged such that the electromagnetic beam (11) strikes the first beam splitter, and a portion of the electromagnetic beam (11) is guided from the first beam splitter (102) to the multi-mirror (10), and then strikes the second beam splitter (102). The diaphragm (104) is positioned in the beam path between the two beam splitters (102) such that the beam passes through the diaphragm (104). The mirror of the multi-mirror (10) can be tilted relative to other mirrors such that the mirror straddles an angle (19) and the wavefront (12) that strikes the multi-mirror (10) is divided into two outgoing wavefronts that are phase-shifted relative to each other. The device comprises a second diaphragm (104) and a second multi-mirror (10) having the same configuration as the multi-mirror (10), The electromagnetic beam (11) strikes the first beam splitter (102), which splits it into two partial beams having different propagation directions, each partial beam being directed toward the multi-mirror (10) and the second multi-mirror (10), and then both partial beams are brought into contact with the second beam splitter (102). An apparatus in which one diaphragm (104) is positioned in each of the beam paths between the two beam splitters (102) such that each partial beam passes through one of the diaphragms (104).

2. The apparatus according to claim 1, wherein the mirrors (16, 18) of the multi-mirror (10) are flat.

3. The apparatus according to claim 1, wherein the first and / or second mirrors (16, 18) of the multi-mirror (10) are rotatable about a rotation axis (20).

4. The apparatus according to claim 1, wherein one multi-mirror (10) has a mirror that can be tilted relative to the other mirror, and the other multi-mirror (10) has a mirror that can rotate relative to the other mirror (16, 18) about a rotation axis (20).

5. The apparatus according to claim 1, wherein the first mirror (16) polarizes electromagnetic radiation.

6. The apparatus according to claim 5, wherein the first mirror (16) reflects radiation of a specific polarization and transmits radiation of a different polarization.

7. The apparatus according to claim 1, wherein the camera records the electromagnetic beam (11) that passes through the multi-mirror and is directed from the second beam splitter.

8. The apparatus according to claim 7, wherein the camera is a color camera.

9. The apparatus according to claim 1, wherein at least one diaphragm (104) has an aperture.

10. The apparatus according to claim 9, wherein the aperture comprises a polarizing filter or a frequency filter that allows only specific wavelengths to pass through the diaphragm (104).

11. The apparatus according to claim 1, wherein one diaphragm (104) is designed as a grating diaphragm having an aperture.

12. The apparatus according to claim 1, wherein at least one diaphragm (104) has two apertures, the apertures having a specific slit width of two dimensions, the slit widths being the same in dimension.

13. Equipped with a single mirror, The beam splitter (102), the single mirror, and the multi-mirror (10) are provided such that the electromagnetic beam strikes the first beam splitter (102) and is split by the first beam splitter into two partial beams having different propagation directions. One of the two partial beams is directed towards the multi-mirror (10) and then strikes the second beam splitter (102), and the second of the two partial beams is directed towards the single mirror and then strikes the second beam splitter (102), The apparatus according to claim 1, wherein one diaphragm (104) is positioned in each of the beampaths of the partial beams between the two beam splitters (102) such that each partial beam passes through one of the diaphragms (104).

Images