Optical apparatus and control method thereof

Abstract

The invention provides an optical device and a control method thereof, relates to the field of optics, and can solve the problem that light uniformization cannot be realized due to interference patterns generated by coherent light. The optical device comprises a coherent light source, a first reflector and an illumination system. The first mirror is rotatable. The reflecting surface of the first reflecting mirror comprises a plurality of unit reflecting mirrors; the reflecting surfaces of the plurality of unit reflectors are curved surfaces and have intermediate-frequency roughness, and the intermediate-frequency roughness is greater than or equal to lambda / 4; wherein lambda is the light wavelength of the coherent light source; a light beam emitted by the coherent light source is reflected by the rotating first reflector and then is divided into a plurality of sub light beams by the illumination system and projected to an object plane.

Description

Technical Field

[0001] The present application relates to the field of optics, and in particular to an optical device and a control method thereof. Background Art

[0002] Optical systems are playing an increasingly important role in the modern information society. For example, large-scale integrated circuits required for information generation and transmission are generally manufactured and tested using optical systems. Optical systems are generally divided into imaging systems and non-imaging systems. Among them, optical imaging systems can clearly image objects on the required medium, which greatly improves the cognition and productivity of human society, such as microscopes, projectors, and semiconductor equipment.

[0003] With the continuous evolution of optical technology, the optical resolution of optical systems has been continuously improved, and the imaging wavelength has been continuously reduced from the visible light band to the short wavelength band. At present, most of the light sources used in short-wavelength optical imaging systems are coherent light sources, which can easily produce interference fringes or interference speckle phenomena, causing the uniformity of the illumination field (i.e., the field of view or light field) to decrease. Therefore, decorrelation processing must be performed first to achieve the uniform light effect to ensure the normal operation of the optical system. Summary of the invention

[0004] The present application provides an optical device and a control method thereof, which can solve the problem that light cannot be uniformed due to interference patterns generated by coherent light.

[0005] The present application provides an optical device, including a coherent light source, a first reflector, and an illumination system. The first reflector can rotate. The reflective surface of the first reflector includes a plurality of unit reflectors. The reflective surfaces of the plurality of unit reflectors are curved surfaces, and the reflective surfaces of the plurality of unit reflectors have a mid-frequency roughness, and the mid-frequency roughness is greater than or equal to λ / 4; wherein λ is the wavelength of light of the coherent light source. After being reflected by the rotating first reflector, the light beam emitted by the coherent light source is split into a plurality of sub-beams by the illumination system and projected onto an object surface.

[0006] When the optical device provided by the present application is in operation, after the coherent light beam emitted by the coherent light source is incident on the rotating first reflector, the curved reflective surface of the unit reflector can continuously adjust the emission direction of the light beam and continuously change the phase of the reflected light, thereby continuously changing the diffraction pattern of the illumination field while pre-homogenizing the light beam, thereby increasing the uniformity of the illumination field; that is, achieving the purpose of time domain decoherence and homogenization. On the other hand, since the reflective surfaces of multiple unit reflectors have a specific intermediate frequency roughness (≥λ / 4), the phase of the reflected light can be further randomized to improve the uniformity of the illumination field. In addition, since the specific intermediate frequency roughness can constrain the reflection divergence angle of the light, it can ensure that the light passing through the unit reflector has no obvious large-angle scattering, reducing the loss of light energy and improving the light utilization rate.

[0007] In some possible implementations, the reflecting surfaces of the multiple unit reflectors are one or more of a spherical surface, a toroidal surface, an aspherical surface, and a free-form surface.

[0008] In some possible implementations, the reflective surfaces of the plurality of unit reflectors are convex. The lighting system includes a reflector array; the first reflector and the reflector array satisfy the relationship: R is the radius of curvature of the reflective surface of the unit reflector; L is the distance between the first reflector and the reflector array; D F is the diameter of the reflector array; D E is the diameter of the incident light beam received by the first reflector; D M is the diameter of the unit reflector. In this case, the reflector array can be located in the maximum integration area of ​​the first reflector, thereby ensuring that the light intensity distribution on the reflector array is as uniform as possible.

[0009] In some possible implementations, the reflective surfaces of the plurality of unit reflectors are concave. The lighting system includes a reflector array; the first reflector and the reflector array satisfy the relationship: R is the radius of curvature of the reflective surface of the unit reflector; L is the distance between the first reflector and the reflector array; D F is the diameter of the reflector array; D E is the diameter of the incident light beam received by the first reflector; D M is the diameter of the unit reflector. In this case, the reflector array can be located in the maximum integration area of ​​the first reflector, thereby ensuring that the light intensity distribution on the reflector array is as uniform as possible.

[0010] In some possible implementations, the curvature radius of the reflective surface of the unit reflector is 1 mm to 1000 mm.

[0011] In some possible implementations, the optical device may further include a second reflector; the reflective surface of the second reflector is a curved surface; and the second reflector is disposed on the optical path between the first reflector and the lighting system. In this case, the light reflected by the first reflector may form an intermediate focus after being reflected by the reflective surface of the second reflector, thereby enabling the size and divergence angle of the light beam incident on the lighting system to be adjustable within a certain range.

[0012] In some possible implementations, a plurality of unit reflectors are periodically and continuously arranged to improve the uniformity of the illumination field.

[0013] In some possible implementations, the wavelength of light emitted by the coherent light source is in the range of 1 nm to 120 nm.

[0014] The present application also provides a control method for an optical device as provided in any of the above possible implementations, the control method comprising: controlling a first reflector to rotate, controlling a light beam emitted by a coherent light source to be projected onto a reflective surface of the first reflector, and splitting the reflected light beam from the first reflector into a plurality of sub-beams through an illumination system and projecting the sub-beams onto an object surface.

[0015] By adopting the above control method, by controlling the first reflector to rotate, the light beam emitted by the coherent light source can continuously adjust the emission direction of the light beam after being reflected by the first reflector, and continuously change the phase of the reflected light, so that while pre-homogenizing the light beam, the diffraction pattern of the illumination field is continuously changed to increase the uniformity of the illumination field; that is, the purpose of time domain decoherence and homogenization is achieved. On the other hand, since the reflective surfaces of the multiple unit reflectors have a specific intermediate frequency roughness (≥λ / 4), the phase of the reflected light can be further randomized to improve the uniformity. And since the specific intermediate frequency roughness can constrain the reflection divergence angle of the light, it can ensure that the light passing through the unit reflector has no obvious large-angle scattering, reducing the loss of light energy and improving the light utilization rate.

[0016] In some possible implementations, controlling the light beam emitted by the coherent light source to be projected onto the reflective surface of the first reflector includes: controlling the light beam emitted by the coherent light source to be grazingly incident on the reflective surface of the first reflector. Compared with the light beam emitted by the coherent light source being incident on the reflective surface of the first reflector, the grazing incidence method can reduce the heat load on the first reflector, thereby improving the light energy utilization rate of the light beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of an optical device provided in an embodiment of the present application;

[0018] Figure 2 A cross-sectional schematic diagram of a first reflector provided in an embodiment of the present application;

[0019] Figure 3 A schematic diagram of the structure of an optical device provided in an embodiment of the present application;

[0020] Figure 4 A schematic structural diagram of a first reflector provided in an embodiment of the present application;

[0021] Figure 5 A schematic structural diagram of a first reflector provided in an embodiment of the present application;

[0022] Figure 6 A schematic structural diagram of a first reflector provided in an embodiment of the present application;

[0023] Figure 7 A schematic diagram of an optical principle provided in an embodiment of the present application;

[0024] Figure 8 A schematic diagram of an optical principle provided in an embodiment of the present application;

[0025] Fig. 9 A schematic diagram of a partial structure of an optical device provided in an embodiment of the present application;

[0026] Fig.10 A flow chart of a control method for an optical device provided in an embodiment of the present application;

[0027] Fig.11 A schematic diagram of a partial structure of an optical device provided in an embodiment of the present application;

[0028] Fig.12 A schematic diagram of the partial structure of an optical device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] The terms "first", "second", etc. in the specification embodiments, claims and drawings of the present application are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one (item)" means one or more, and "multiple" means two or more. "Installation", "connection", "connected", etc. should be understood in a broad sense, for example, it can be an electrical connection or a mechanical connection; it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or it can be indirect through an intermediate medium, or it can be the internal connection of two elements. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, including a series of steps or units. Methods, systems, products or devices are not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products or devices. "Up", "down", "left", "right", etc. are only used relative to the orientation of the components in the drawings. These directional terms are relative concepts. They are used for description and clarification relative to the description, which may change accordingly according to the change of the orientation of the components in the drawings.

[0031] An embodiment of the present application provides an optical device, in which a rotating reflector (i.e., the first reflector hereinafter) is provided to pre-homogenize a coherent light beam, thereby causing a random change in the diffraction pattern (such as stripes, speckles, etc.) of the illuminated field of view, thereby making the accumulated light intensity of the illuminated field of view uniform within the exposure time, thereby achieving time-domain decoherence and homogenization of the coherent light, and solving the problem in the related art that the coherent light generates an interference pattern and cannot homogenize the light.

[0032] The specific configuration structure of the optical device provided in the embodiment of the present application is schematically described below.

[0033] An embodiment of the present application provides an optical device, which can be used in the field of short-wavelength optics and uses short-wavelength soft X-rays with a wavelength of 1nm to 120nm as an imaging light source, but is not limited to this.

[0034] like Figure 1 As shown, the optical device 01 may include a coherent light source 1, a first reflector 2, and an illumination system 3. The first reflector 2 can rotate, for example, the first reflector 2 can rotate driven by a rotating device.

[0035] As shown, the coherent light source 1 can be a short-wavelength light source, that is, the wavelength λ of the light emitted by the coherent light source 1 is shorter than 200nm, for example, it can be in the range of 3nm to 120nm. In the present application, there is no limitation on the setting form of the coherent light source 1, and the coherent light source 1 can be a plasma laser light source, a synchrotron radiation light source, a free electron laser (FEL) light source, etc.

[0036] The above-mentioned coherent light source 1 can be a continuous wave light source or a pulse light source. The pulse width δ of the pulse light source can be in the order of femtoseconds, picoseconds, nanoseconds, microseconds, or milliseconds, and the pulse repetition frequency can be in the range of several Hz to several hundred GHz.

[0037] The above-mentioned illumination system 3, as an important component of the optical imaging system, is crucial to improving the performance of the entire optical system. Its main functions are to provide uniform illumination for the object plane 4, control the imaging dose and achieve a certain pupil filling.

[0038] In the optical device provided by the present application, a rotatable first reflector 2 is additionally arranged on the optical path between the coherent light source 1 and the illumination system 3. When the first reflector 2 is rotating at high speed, the reflection angle and phase of the reflected light beam emitted by the coherent light source 01 are continuously changed after being reflected by the rotating first reflector 2, so that the interference pattern projected onto the object surface 4 (i.e., the illumination surface) after being divided into multiple sub-beams by the illumination system 3 can be continuously changed, and the accumulated light intensity of the illumination field within the exposure time (typically about 1 ms) is uniformized, thereby realizing time-domain decoherence and uniform light of the coherent or partially coherent light source.

[0039] The present application is further described below in conjunction with the specific structure of the first reflector 2 .

[0040] Figure 2 A schematic cross-sectional view of the first reflector 2 provided in an embodiment of the present application.

[0041] refer to Figure 2 As shown, the reflective surface of the first reflector 2 may include a plurality of unit reflectors 20, and the reflective surfaces of the plurality of unit reflectors 20 are all curved surfaces, and the reflective surfaces of the plurality of unit reflectors 20 have a mid-frequency roughness, and the value of the mid-frequency roughness is greater than or equal to λ / 4 (i.e., has a specific mid-frequency roughness), wherein λ is the wavelength of the light of the coherent light source. It should be understood here that the mid-frequency roughness refers to the roughness on a scale of 1μm to 1mm in spatial frequency.

[0042] In some possible implementations, the reflective surfaces of the above-mentioned multiple unit reflectors 20 can be one or more of a spherical surface, a toroidal surface, an aspherical surface (i.e., a high-order aspherical surface), and a free-form surface. In other words, the reflective surfaces of the multiple unit reflectors 20 can be the same or different, and the present application does not limit this. The following embodiments are all based on the fact that the reflective surfaces of the multiple unit reflectors 20 are the same, such as all spherical surfaces or all toroidal surfaces.

[0043] When the optical device is working, after the coherent light beam emitted by the coherent light source 1 is incident on the rotating first reflector 2, the curved reflective surface of the unit reflector 20 can continuously adjust the emission direction of the light beam and continuously change the phase of the reflected light, thereby pre-homogenizing the light beam while continuously changing the diffraction pattern of the illumination field and increasing the uniformity of the illumination field; that is, achieving the purpose of time domain decoherence and homogenization.

[0044] On this basis, since the reflective surfaces of the multiple unit reflectors 20 have a specific mid-frequency roughness (≥λ / 4), the phase of the reflected light can be further randomized to improve the uniformity of the illumination field. In addition, since the specific mid-frequency roughness can constrain the reflection divergence angle of the light, it can also ensure that the light passing through the unit reflector has no obvious large-angle scattering, reduce light energy loss, and improve light utilization.

[0045] In addition, by providing the rotating first reflector 2, the illumination light beam shaping and beam expansion with a smaller optical extension can be achieved, which is beneficial to the miniaturization and integration of the system.

[0046] It should be understood that the short-wavelength light source (1) can be shaped, homogenized, and the lighting mode adjusted through the lighting system 3 to form a lighting area of ​​a certain shape on the object plane 4 and select a suitable lighting mode.

[0047] Indicative, reference Figure 3 As shown, in the optical device, after the light beam is reflected by the curved surface of the unit reflector 20 in the first reflector 2, it is incident on the reflector array 31 in the lighting system 3 and divided into multiple sub-beams, and further shaped. Of course, other beam shaping mirrors can also be included in the lighting system 3 as needed. In this case, the reflection angle and phase of the reflected light beam through the first reflector 2 are constantly changing, so that the uniformity of the incident light incident on the reflector array 31 can be improved; at the same time, because the curved surface of the unit reflector 20 adopts a specific intermediate frequency roughness (≥λ / 4), the phase of the reflected light can be further randomized, and the reflection divergence angle of the light can be constrained, so that it can be ensured that the light through the unit reflector has no obvious large-angle scattering, and the amount of light incident on the reflector array 31 is increased, that is, the light utilization rate is improved. In other words, by setting the first reflector 2, the light beam incident on the lighting system 3 can be pre-homogenized, so that the uniformity of the incident light of the lighting system can be greatly improved.

[0048] The specific structure of the first reflector 2 is further described below.

[0049] The present application does not limit the overall surface shape of the first reflector 2. For example, the overall surface shape of the first reflector 2 can be a plane mirror, a spherical surface, an aspherical surface, a free-form surface, etc. Schematically, in some embodiments, the surface shape of the first reflector 2 can be set to be a plane mirror.

[0050] In addition, in some possible implementations, the plurality of unit reflectors 20 in the first reflector 2 may be a plurality of independent reflectors. In some possible implementations, the first reflector 2 is an integrated structure, and the plurality of unit reflectors 20 are formed by processing the reflective surface of the first reflector 2. This application does not limit this, and it can be set as needed in practice.

[0051] The present application does not limit the arrangement of the unit reflectors 20 in the first reflector 2. In some possible implementations, in order to improve the uniformity of the illumination field, multiple unit reflectors 20 in the first reflector 2 can be arranged periodically and continuously. In addition, the shapes of the multiple unit reflectors 20 in the first reflector 2 directly determine the shape of the light beam incident on the reflector array 31, and the present application does not limit the shape of the unit reflectors 20.

[0052] For example, Figure 4 As shown, in some embodiments, the unit reflector 20 may be circular, and a plurality of unit reflectors 20 in the first reflector 2 may be continuously arranged in both the horizontal and vertical directions.

[0053] For example, Figure 5 As shown, in some embodiments, the unit reflector 20 may be rectangular, and a plurality of unit reflectors 20 in the first reflector 2 may be continuously arranged in both the horizontal and vertical directions.

[0054] For example, Figure 6 As shown, in some embodiments, the unit reflector 20 may be hexagonal, and a plurality of unit reflectors 20 in the first reflector 2 may be arranged in a honeycomb shape.

[0055] In addition, in some possible implementations, the curvature radius of the reflective surface of the unit reflector 20 is 1 mm to 1000 mm. In some embodiments, the curvature radius of the reflective surface of the unit reflector 20 can be set to 1 mm, 100 mm, 1000 mm, etc.

[0056] In addition, taking the case where parallel light is incident on the first reflector 2 as an example, in order to ensure that the light intensity distribution on the reflector array 31 is as uniform as possible, the reflector array 31 can be set to be located in the maximum integration area of ​​the first reflector 2. The following describes the setting conditions for the reflector array 31 to be located in the maximum integration area of ​​the first reflector 2 when the reflective surfaces of the unit reflectors 20 in the first reflector 2 are convex or concave, respectively, according to the laws of geometric optics.

[0057] refer to Figure 7 As shown, when the reflecting surface of the unit reflector 20 in the first reflector 2 is a convex surface, the relationship between the reflector array 31 and the first reflector 2 satisfies the following equation: Thus, the reflector array 31 can be located in the maximum integration area of ​​the first reflector 2. Wherein, R is the curvature radius of the reflective surface of the unit reflector 20; L is the distance between the first reflector 2 and the reflector array 31; D F is the diameter of the reflector array 31; D E D is the diameter of the incident light beam received by the first reflector 2; M is the diameter of the unit reflector 20 .

[0058] refer to Figure 8 As shown, when the reflective surface of the unit reflector 20 in the first reflector 2 is a concave surface, the reflector array 31 and the first reflector 2 satisfy the relationship: Thus, the reflector array 31 can be located in the maximum integration area of ​​the first reflector 2. Wherein, R is the curvature radius of the reflective surface of the unit reflector 20; L is the distance between the first reflector 2 and the reflector array 31; D F is the diameter of the reflector array 31; D E D is the diameter of the incident light beam received by the first reflector 2; M is the diameter of the unit reflector 20 .

[0059] As an example, taking the coherent light source 1 as a short-wavelength light source, the diameter of the light beam emitted by the light source (i.e., D E ) may be 0.1 mm to 10 mm. For example, in some embodiments, D E The diameter D of the unit reflector 20 may be 0.1 mm, 0.5 mm, 1 mm, 2 mm, 5 mm, 10 mm, etc. M Can be D E / 2, D E / 3, D E / 5, D E / 10, etc. For example, in some embodiments, the diameter D of the unit reflector 20 is M It can be 0.01mm~10mm.

[0060] It can be understood that the diameter D of the unit reflector 20 is M The smaller the diameter D is, the more times the incident light beam can be split and integrated, and the better the light homogenization effect is. For example, compared with not setting the first reflector 2, the diameter D of the unit reflector 20 in the first reflector 2 is M D E / 3, the beam uniformity on the reflector array 31 can be improved from 10% to 90%.

[0061] In addition, in order to shape the reflected light beam through the first reflector 2, in some possible implementation methods, such as Fig. 9 As shown, a second reflector M can be arranged on the optical path between the first reflector 2 and the lighting system 3, and the reflective surface of the second reflector M is a curved surface, so that the light reflected by the first reflector 2 can form an intermediate focus (IF) after being reflected by the reflective surface of the second reflector M, so that the size and divergence angle of the light beam incident to the reflector array 31 in the lighting system 3 can be adjusted within a certain range.

[0062] The surface shape of the second reflector M can be a spherical surface, an aspherical surface or a free-form surface, etc.; the reflecting surface of the second reflector M can be a convex surface or a concave surface; the present application does not impose any restrictions on this, and it can be set as needed in practice.

[0063] In addition, the present invention also provides a method for the aforementioned optical device (see Figure 1 ) control methods, such as Fig.10 As shown, the control method may include:

[0064] Step 01: Control the first reflector 2 to rotate.

[0065] As shown, the first reflector 2 can be rotated by controlling the rotating device, and the rotating device can drive the first reflector 2 to rotate. The rotation speed of the first reflector 2 can be 100 RPM (revolutions per minute) to 100000 RPM.

[0066] Step 02, control the light beam emitted by the coherent light source 1 to be projected onto the reflective surface of the first reflector 2, and split the reflected light beam from the first reflector 2 into a plurality of sub-beams through the illumination system 3 and then project them onto the object surface 4.

[0067] In this case, after the coherent light beam emitted by the coherent light source 1 is incident on the rotating first reflector 2, the curved reflective surface of the unit reflector 20 can continuously adjust the emission direction of the light beam and continuously change the phase of the reflected light, thereby continuously changing the diffraction pattern of the illumination field while pre-homogenizing the light beam, thereby increasing the uniformity of the illumination field; that is, achieving the purpose of time domain decoherence and homogenization. On the other hand, since the reflective surfaces of the multiple unit reflectors 20 have a specific intermediate frequency roughness (≥λ / 4), the phase of the reflected light can be further randomized to improve the uniformity. And since the specific intermediate frequency roughness can constrain the reflection divergence angle of the light, it can ensure that the light passing through the unit reflector 20 has no obvious large-angle scattering, reducing the loss of light energy and improving the light utilization rate.

[0068] Regarding the control of the light beam emitted by the coherent light source 1 to be projected onto the reflective surface of the first reflector 2 in the above step 02:

[0069] Indicative, reference Fig. 9 As shown, in some possible implementations, the light beam emitted by the coherent light source 1 can be controlled to be incident on the reflective surface of the first reflector 2. For example, the light beam emitted by the coherent light source 1 can be controlled to be incident on the first reflector 2 at an incident angle less than or equal to 20°.

[0070] Indicative, reference Fig.11 As shown, in some other possible implementations, the light beam emitted by the coherent light source 1 can be controlled to be incident on the reflective surface of the first reflector 2. For example, the light beam emitted by the coherent light source 1 can be controlled to be incident on the first reflector 2 at an incident angle greater than or equal to 70° (for example, 80°).

[0071] It is understandable that compared to Fig. 9 As for the light beam emitted by the coherent light source 1 being incident on the reflecting surface of the first reflecting mirror 2, Fig.11 The grazing incidence method can reduce the heat load on the first reflector 2, thereby improving the light energy utilization rate of the light beam.

[0072] Of course, reference Fig.12 As shown, in the case where the second reflector M is provided in the optical device, in order to improve the light energy utilization rate of the light beam, the light beam emitted by the coherent light source 1 can be controlled to be incident on the first reflector 2 by grazing, and then be incident on the second reflector M after being reflected by the first reflector 2 by grazing. Schematically, the light beam emitted by the coherent light source 1 can be controlled to be incident on the first reflector 2 at an incident angle greater than or equal to 70° (for example, it can be 80°), and then be incident on the second reflector M at an incident angle greater than or equal to 70° (for example, it can be 80°) after being reflected by the first reflector 2.

[0073] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An optical device, It is characterized in that It includes a coherent light source, a first reflector, and an illumination system; the first reflector is rotatable; The reflective surface of the first reflector includes a plurality of unit reflectors; The reflecting surfaces of the plurality of unit reflectors are curved surfaces, and the reflecting surfaces of the plurality of unit reflectors have a mid-frequency roughness, and the mid-frequency roughness is greater than or equal to λ / 4; wherein λ is the wavelength of light of the coherent light source; After being reflected by the rotating first reflector, the light beam emitted by the coherent light source is split into a plurality of sub-beams by the illumination system and projected onto the object surface.

2. The optical device according to claim 1, It is characterized in that The reflecting surfaces of the multiple unit reflectors are one or more of a spherical surface, a toroidal surface, an aspherical surface, and a free-form surface.

3. The optical device according to claim 1 or 2, It is characterized in that The reflecting surfaces of the plurality of unit reflectors are convex surfaces; The lighting system includes a reflector array; The first reflector and the reflector array satisfy the relationship: R is the radius of curvature of the reflective surface of the unit reflector; L is the distance between the first reflector and the reflector array; D F is the diameter of the reflector array; D E is the diameter of the incident light beam received by the first reflector; D M is the diameter of the unit reflector.

4. The optical device according to claim 1 or 2, It is characterized in that The reflecting surfaces of the plurality of unit reflectors are concave surfaces; The lighting system includes a reflector array; The first reflector and the reflector array satisfy the relationship: R is the radius of curvature of the reflective surface of the unit reflector; L is the distance between the first reflector and the reflector array; D F is the diameter of the reflector array; D E is the diameter of the incident light beam received by the first reflector; D M is the diameter of the unit reflector.

5. The optical device according to any one of claims 1 to 4, It is characterized in that The curvature radius of the reflection surface of the unit reflection mirror is 1 mm to 1000 mm.

6. The optical device according to any one of claims 1 to 5, It is characterized in that The optical device also includes a second reflector; The reflecting surface of the second reflector is a curved surface; The second reflector is arranged on the optical path between the first reflector and the illumination system.

7. The optical device according to any one of claims 1 to 6, It is characterized in that The plurality of unit reflective mirrors are periodically and continuously arranged.

8. The optical device according to any one of claims 1 to 7, It is characterized in that The wavelength of the light emitted by the coherent light source is in the range of 1nm to 120nm.

9. A method for controlling an optical device according to any one of claims 1 to 8, It is characterized in that include: controlling the first reflector to rotate; The light beam emitted by the coherent light source is controlled to be projected onto the reflective surface of the first reflector, and the light beam reflected by the first reflector is split into a plurality of sub-beams by the illumination system and then projected onto the object surface.

10. The method for controlling an optical device according to claim 9, It is characterized in that The controlling the light beam emitted by the coherent light source to be projected onto the reflective surface of the first reflector comprises: The light beam emitted by the coherent light source is controlled to be grazingly incident on the reflection surface of the first reflection mirror.

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