Reflector, manufacturing method thereof and optical system

Abstract

The invention provides a reflector, a manufacturing method thereof and an optical system, relates to the field of optics, and can improve the utilization rate of light energy while carrying out random phasing on light rays by adopting the reflector. The reflecting mirror comprises a substrate and a plurality of reflecting units arranged on the substrate. And each reflection unit comprises a plurality of reflection layers and a plurality of transmission layers which are alternately arranged in sequence. Wherein the reflection layer and the transmission layer which are arranged adjacently form a reflection period; the value range of the surface roughness of the reflection unit is 0.05 nm to 1 nm. A surface height difference exists between two adjacent reflection units; and / or the thicknesses of the reflection periods in two adjacent reflection units are different.

Description

Technical Field

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

[0002] With the continuous evolution of optical system technology, optical resolution is constantly improving, and the working wavelength is constantly decreasing to the short-wave optical field. However, in short-wave optical systems that use coherent light sources such as lasers, the spatial coherence of light will cause speckle when the light passes through the optical system, which will eventually lead to a decrease in the quality of the pattern on the image plane, and even breakpoints or connections, causing the imaging pattern to deviate seriously from the designed pattern and cannot be used or observed. Therefore, it is necessary to perform decorrelation processing on the light to avoid the aforementioned problems.

[0003] In the prior art, optical devices such as diffusers and random phase plates are arranged in the optical system to randomize the phase of the coherent light beam to achieve the purpose of decoherence. However, since the existing optical devices such as diffusers and random phase plates are mostly transmissive, they seriously absorb short-wavelength light; or the surface roughness of the components is large, which causes strong absorption and scattering of short-wavelength light, resulting in low light energy utilization, which greatly affects the efficiency of the optical system. Summary of the invention

[0004] The present application provides a reflector and a manufacturing method thereof, and an optical system. The reflector can randomly phase light and improve the utilization rate of light.

[0005] The present application provides a reflector, comprising a substrate and a plurality of reflective units arranged on the substrate. Each reflective unit comprises: a plurality of reflective layers and a plurality of transmissive layers arranged alternately in sequence; wherein the adjacent reflective layers and transmissive layers form a reflective period. The surface roughness of the reflective unit ranges from 0.05 nm to 1 nm. There is a surface height difference between two adjacent reflective units; and / or the thickness of the reflective period in two adjacent reflective units is different.

[0006] The reflector provided in the embodiment of the present application uses a plurality of reflective layers and a plurality of transmissive layers stacked alternately in sequence to form a reflective unit, and by setting the surface roughness of the reflective unit to a value range of 0.05nm to 1nm, that is, having a sub-nanometer surface roughness, it is possible to reduce scattering and absorption of light energy, thereby improving light utilization.

[0007] In one possible implementation, the reflector provided by the present application is provided with a surface height difference between two adjacent reflective units, so that when a coherent light beam is incident on the reflector, it can be divided into multiple sub-beams by multiple reflective units for reflection, and the phases of the multiple sub-beams change due to the surface height difference between the reflective units, and as the reflector rotates, the phase of the reflected light can change randomly. In another possible implementation, by setting the thickness of the reflection period in two adjacent reflective units to be different, when a coherent light beam is incident on the reflector, the light beam passes through different film layers when it penetrates through the thin film of different reflective units and is emitted through Bragg diffraction, so that the light beam after being reflected by different reflective units produces an optical path difference (i.e., a phase difference), and as the reflector rotates, the phase of the reflected light changes randomly, that is, random phase modulation of high spatial frequency is achieved.

[0008] In another possible implementation, the reflector provided by the present application can simultaneously set a surface height difference between two adjacent reflective units, and the thickness of the reflection period in the two adjacent reflective units is different, so that when a coherent light beam is incident on the reflector, it can be divided into multiple sub-beams by multiple reflective units for reflection, and the phases of the multiple sub-beams change due to the existence of the surface height difference between the reflective units. At the same time, when the multiple sub-beams penetrate the thin films of different reflective units and are emitted through Bragg diffraction, the depths of the film layers passed through are different, so that the light beams reflected by different reflective units produce optical path differences (i.e., phase differences); in this way, as the reflector rotates, the phase of the reflected light can change randomly.

[0009] In some possible implementations, the surface height difference Δh between two adjacent reflective units ranges from 0.1nm to 10nm. By setting Δh≥0.1nm, the light reflected by two adjacent reflective units can have an obvious phase difference, so that the various randomly arranged height differences on the reflector can ensure that the light has a good degree of randomization. By setting Δh≤10nm, it is possible to avoid obvious scattering due to a large height difference between two adjacent reflective units, thereby ensuring the utilization rate of light.

[0010] In some possible implementations, in a single reflection unit, all reflection layers have the same thickness and all transmission layers have the same thickness to simplify the manufacturing process.

[0011] In some possible implementations, the thicknesses of the reflection periods in two adjacent reflection units are different, and the surface height difference between the two adjacent reflection units is less than 0.5 nm, thereby reducing the random scattering problem caused by the height difference between the two reflection units.

[0012] In some possible implementations, the thickness difference of the reflection period in two adjacent reflection units ranges from 0.1nm to 1nm. By setting the thickness difference of the reflection period in two adjacent reflection units to be greater than or equal to 0.1nm, it can be ensured that the light reflected by the two adjacent reflection units has a significant phase difference, and thus the randomly distributed thickness difference in multiple reflection units can ensure that the light has a good degree of randomization. By setting the thickness difference of the reflection period in two adjacent reflection units to be less than or equal to 1nm, it can be avoided that the central reflection band of multiple reflection units deviates too much due to the excessive thickness difference of the reflection period, thereby reducing the reflectivity of the required band, and also prevents the surface from having a large height difference, that is, it is easier to control the surface height difference between the reflection units to be less than 1nm.

[0013] In some possible implementations, 10 to 100 reflection periods are provided in the reflection unit. By providing more than 10 groups of reflection layers and transmission layers in the reflection unit, it is possible to ensure that the reflection unit has a high reflection efficiency, and by providing less than 100 groups of reflection layers and transmission layers in the reflection unit, the manufacturing process can be simplified.

[0014] In some possible implementations, the transmission layer includes one or more of Si (silicon), Be (beryllium), C (carbon), B (boron), B4C (boron carbide), Sr (strontium), and Sc (scandium).

[0015] In some possible implementations, the reflective layer includes one or more of Nb (niobium), Ni (nickel), Au (gold), Ru (ruthenium), Rh (rhodium), Mo (molybdenum), Cr (chromium), Co (cobalt), La (lanthanum), and W (tungsten).

[0016] In some possible implementations, the lateral dimension of the reflective unit ranges from 10 nm to 1 mm.

[0017] In some possible implementations, the reflector has a plane, a spherical surface, or an aspherical surface.

[0018] The present application also provides an optical system, comprising a coherent light source, an illumination system, and at least one reflector provided in any of the possible implementation methods described above; the light beam emitted by the coherent light source is split into multiple sub-beams by the illumination system and then projected onto an illumination surface; the reflector is arranged on the light path between the coherent light source and the illumination surface.

[0019] The present application also provides a method for manufacturing a reflector, which may include: providing a substrate; alternately manufacturing multiple reflective layers and multiple transmissive layers in multiple reflective regions on the substrate to form multiple reflective units; wherein the reflective layers and the transmissive layers adjacently arranged in the reflective units form a reflective period; the surface roughness of the reflective units ranges from 0.05nm to 1nm; there is a surface height difference between two adjacent reflective units; and / or the thickness of the reflective period in two adjacent reflective units is different.

[0020] In some possible implementations, multiple reflective layers and multiple transmissive layers are alternately produced in different reflective regions on a substrate, which may include: using magnetron sputtering or atomic layer deposition to alternately deposit multiple reflective layers and multiple transmissive layers in different reflective regions on a substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A structural diagram of an optical system provided in an embodiment of the present application;

[0022] Figure 2 A schematic diagram of a planar structure of a reflector provided in an embodiment of the present application;

[0023] Figure 3 for Figure 2 Schematic diagram of the cross section along the OO' position;

[0024] Figure 4 A schematic diagram of the structure of a reflector provided in an embodiment of the present application;

[0025] Figure 5 A schematic diagram of a planar structure of a reflector provided in an embodiment of the present application;

[0026] Figure 6 A flow chart of a method for manufacturing a reflector provided in an embodiment of the present application;

[0027] Figure 7 A schematic diagram of a reflector in the manufacturing process provided by an embodiment of the present application;

[0028] Figure 8 Schematic diagram of two masks used in manufacturing reflectors provided in the embodiments of the present application;

[0029] Fig. 9 A schematic diagram of a reflector during the manufacturing process provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] 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 them. 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.

[0031] 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 represent: 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 associated objects before and after are in an "or" relationship. "At least one (item)" refers to one or more, and "multiple" refers to two or more. "At least one of the following (items)" or similar expressions refers to any combination of these items, including any combination of single items (items) or plural items (items). For example, at least one of a, b or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple. "Installation", "connection", "connected" and the like should be understood in a broad sense, for example, 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 internal communication between two elements. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, inclusion of a series of steps or units. Methods, systems, products or devices are not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. "Up", "down", "left", "right" and the like are only used relative to the orientation of 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 changes in the orientation of the components in the drawings.

[0032] An embodiment of the present application provides an optical system, which arranges a new type of random phase element on the optical path between a coherent light source and an illumination surface. On the one hand, the random phase element includes a large number of reflection units capable of performing random phases, which can avoid the formation of interference / speckle patterns on the illumination surface by continuously changing the phase of the reflected light, thereby improving the uniformity of the light intensity of the light field and achieving the purpose of decoherence; on the other hand, the reflection surface of the random phase element adopts a sub-nanometer roughness, which reduces the loss of light energy due to scattering and absorption, improves the reflectivity of light (that is, improves the utilization rate of light); and at the same time improves the resistance to radiation damage.

[0033] The following is a brief description of the application of random phase elements in optical systems.

[0034] Figure 1 A schematic diagram of an optical system provided in an embodiment of the present application.

[0035] refer to Figure 1 As shown, an embodiment of the present application provides an optical system, which includes a coherent light source 1, a reflector 2, an illumination system 3, and an illumination surface 4. When the optical system is in use, the light beam emitted by the coherent light source 1 is reflected by the reflector 2 and then incident on the illumination system 3, and is projected by the illumination system 3 to the illumination area (i.e., illumination field or illumination surface) of the illumination surface 4 to complete the illumination.

[0036] The reflector 2 can adopt a new type of random phase element. When the optical system is used, the reflector 2 is controlled to rotate so that the phase of the light beam emitted by the coherent light source 1 can change randomly after being reflected by the reflection unit of the reflector 2. In this case, the light beam with randomly changed phase forms a uniform light field on the illumination surface 4 after passing through the illumination system 3; that is, by setting the reflector 2 to randomize the phase of the light beam emitted by the coherent light source 1, the formation of interference / speckle pattern on the illumination surface 4 is avoided, the light intensity uniformity of the light field is improved, and the purpose of decoherence is achieved.

[0037] In addition, compared with micrometer-level or nanometer-level reflective surfaces, the reflector 2 has a sub-nanometer-level surface roughness, which can reduce light energy loss due to scattering and absorption, improve reflectivity (that is, improve light utilization), and also improve radiation damage resistance.

[0038] The present application does not limit the specific configuration of the above-mentioned coherent light source 1. For example, in some possible implementations, the coherent light source 1 can be various types of high-coherence laser light sources.

[0039] It can be understood here that some high-coherence light sources have a pulse width of femtoseconds and therefore bring extremely high peak power. High roughness will reduce the material's resistance to radiation damage. The reflector provided in the embodiment of the present application has a sub-nanometer surface roughness, which can increase the damage threshold, that is, improve the resistance to radiation damage.

[0040] It should be noted here that Figure 1 The example of setting a reflector 2 on the optical path between the coherent light source 1 and the illumination surface 4 is only used for illustration, but the present application is not limited thereto. In practice, one or more reflectors 2 can be set on the optical path between the coherent light source 1 and the illumination surface 4 as needed to achieve the purpose of decoherence.

[0041] For example, in some possible implementations, two or more reflectors 2 may be arranged on the optical path between the coherent light source 1 and the illumination system 3 .

[0042] The specific configuration of the reflector 2 provided in the embodiment of the present application is described below in conjunction with specific embodiments.

[0043] Embodiment 1

[0044] Figure 2 A schematic plan view of a reflector 2 provided in an embodiment of the present application, Figure 3 for Figure 2 Schematic diagram of the cross section along the OO' position.

[0045] refer to Figure 2 and Figure 3 As shown, a reflector 2 provided in an embodiment of the present application may include a substrate 20 and a plurality of reflective units U disposed on the substrate 20. The reflective units U are provided with a plurality of reflective layers a and a plurality of transmissive layers b alternately stacked in sequence, wherein the adjacent reflective layers a and transmissive layers b form a reflective period T.

[0046] Indicatively, the thickness of a reflection period T can be set to be approximately half the wavelength of the incident light received by the reflection unit U (i.e., λ / 2). In this case, the reflectivity of the reflector 2 reaches a maximum value in the λ band according to the Bragg diffraction law (2Tsinθ=nλ). For example, taking the reflector 2 receiving coherent light with a wavelength of λ=100nm as an example, the thickness of a reflection period T can be set to be approximately 50nm.

[0047] In this embodiment, the thickness of the reflection period T in the same reflection unit U may be the same or different. The thickness of the reflection period T in different reflection units U may be the same or different; this application does not impose any limitation on this.

[0048] For example, in some possible implementations, the thickness of multiple reflective layers a in different reflective units U may be the same, and the thickness of multiple transmissive layers b may be the same, that is, the thickness of the reflective period T may be the same (eg, may be about 7 nm);

[0049] For example, in some possible implementations, the thickness of one or more reflection periods T in different reflection units U close to the substrate 20 can be set to be different to adjust the height difference between two adjacent reflection units U, and the thickness of the remaining reflection periods T can be the same.

[0050] In addition, the present application does not limit the number of reflection periods T set in each reflection unit U, and it can be set as needed in practice.

[0051] For example, in some possible implementations, about 10 to 100 reflection periods T may be generally provided in each reflection unit U, that is, 10 to 100 groups of reflection layers a and transmission layers b may be provided. For example, about 10 reflection periods T may be provided in some reflection units U; for another example, 50 reflection periods T may be provided in some reflection units; for another example, about 100 reflection periods T may be provided in some reflection units U.

[0052] Optionally, 40 to 60 groups of reflection layers a and transmission layers b may be provided in the reflection unit U. By providing more than 40 groups of reflection layers a and transmission layers b in the reflection unit U, it is possible to ensure that the reflection unit U has a high reflection efficiency, and by providing less than 60 groups of reflection layers a and transmission layers b in the reflection unit U, the manufacturing process can be simplified.

[0053] In addition, refer to Figure 3 As shown, in the reflector 2, the surface roughness of the reflective unit U can be in the range of 0.05nm to 1nm, that is, the reflective unit U has a sub-nanometer surface roughness, which can reduce the scattering and absorption of light energy, thereby improving the utilization rate of light.

[0054] In some possible implementations, the surface height difference Δh between two adjacent reflection units U may be in the range of 0.1 nm to 10 nm. In this way, when the coherent light beam is incident on the reflector 2, it is divided into multiple sub-beams by multiple reflection units U for reflection, and the phases of the multiple sub-beams change due to the surface height difference between the reflection units U, and as the reflector 2 rotates, the phase of the reflected light can change randomly.

[0055] For the surface height difference Δh between the two adjacent reflection units U mentioned above being 0.1nm to 10nm:

[0056] By setting Δh≥0.1nm, the light reflected by two adjacent reflection units U can have an obvious phase difference (such as a variation amplitude of more than λ / 4). In this way, the various randomly arranged height differences on the reflector 2 can ensure that the light has a good degree of randomization.

[0057] By setting Δh≤10 nm, it is possible to avoid obvious scattering due to a large height difference between two adjacent reflection units U, thereby ensuring the utilization rate of light.

[0058] Schematically, the surface of the entire reflector 2 can adopt 2 to 16 steps, that is, 2 to 16 different surface height differences Δh can be set, but it is not limited thereto.

[0059] For example, in some possible implementations, the surface of the reflector 2 may be provided with 2 to 4 different surface height differences Δh.

[0060] In addition, in the present application, the reflective unit U may include a reflective layer a and a transmissive layer b made by high-precision coating, such as magnetron sputtering, atomic layer deposition, etc. In this way, the reflective unit U can meet the sub-nanometer surface roughness requirement, while ensuring that the surface height difference Δh between two adjacent reflective units U is within the range of 0.1nm to 10nm.

[0061] Regarding the specific manufacturing method of the reflection unit U, reference may be made to the subsequent embodiment of the manufacturing method of the reflection mirror, which will not be described in detail here.

[0062] Embodiment 2

[0063] Figure 4 This is a schematic diagram of a reflector provided in the second embodiment.

[0064] refer to Figure 4 As shown, the second embodiment provides a reflector 2 , which includes a substrate 20 and a plurality of reflective units U disposed on the substrate 20 .

[0065] The reflective unit U is provided with a plurality of reflective layers a and a plurality of transmissive layers b which are alternately stacked in sequence, and the adjacent reflective layers a and transmissive layers b form a reflective period T. The surface roughness of the reflective unit U is 0.05 nm to 1 nm, that is, it has a sub-nanometer surface roughness, so as to reduce the loss of light energy due to scattering and absorption, thereby improving the utilization rate of light.

[0066] The surface height difference between two adjacent reflection units U is less than 0.5 nm, that is, the surfaces of two adjacent reflection units U are roughly flush, or the thicknesses of all reflection units U are nearly equal; thereby reducing the random scattering problem caused by the height difference between the two reflection units U.

[0067] On this basis, in order to ensure that the reflector 2 can achieve decoherence of the light, the thickness of the reflection period T in two adjacent reflective units U can be set to be unequal. In this way, when the coherent light beam is incident on the reflector 2, the light beam penetrates the thin films of different reflective units and exits through Bragg diffraction, and the depth of the film layer passed through is different, so that the light beam after being reflected by different reflective units U produces an optical path difference (i.e., a phase difference), and as the reflector 2 rotates, the phase of the reflected light changes randomly, thereby achieving random phase modulation with high spatial frequency.

[0068] It should be noted that in the second embodiment, there is no restriction on the thickness difference of the reflection period T in two adjacent reflection units U, as long as the phase of the reflected light can be randomized.

[0069] Illustratively, in some possible implementations, the thickness difference of the reflection period T in two adjacent reflection units U may be 0.1 nm to 1 nm.

[0070] By setting the thickness difference of the reflection period T in two adjacent reflection units U to be greater than or equal to 0.1 nm, the light reflected by the two adjacent reflection units U can have an obvious phase difference (such as a variation amplitude of more than λ / 4). In this way, the randomly distributed thickness difference in multiple reflection units U can ensure that the light has a good degree of randomization.

[0071] By setting the thickness difference of the reflection period T in two adjacent reflection units U to be less than or equal to 1 nm, it is possible to avoid excessive deviation of the central reflection band of multiple reflection units U due to excessive thickness difference of the reflection period T, thereby reducing the reflectivity of the required band. At the same time, it also prevents large height differences on the surface, that is, it is easier to control the surface height difference between the reflection units U to be less than 1 nm.

[0072] In addition, in the second embodiment, the thickness of the reflection period T in the same reflection unit U may be the same or different, and the present application does not impose any limitation on this; for details, please refer to the relevant description of the aforementioned first embodiment.

[0073] As shown, in some possible implementations, the thickness of multiple reflective layers a and the thickness of multiple transmission layers b in the same reflective unit U can be set to be the same; that is, the thickness of the reflection period T is the same. For two adjacent reflective units U (the first reflective unit and the second reflective unit), the thickness of the reflection period T set in the first reflective unit can be set to 10.1 nm, and 50 reflection periods T are set in the first reflective unit, and the total thickness of the first reflective unit is about 505 nm. The thickness of the reflection period T in the second reflective unit can be set to 9.9 nm, and 51 reflection periods T are set in the second reflective unit, and the total thickness of the second reflective unit is about 504.0 nm; in this case, the surface height difference between the first reflective unit and the second reflective unit is less than 1 nm, that is, the total thickness of the two adjacent reflective units U is basically the same.

[0074] Of course, in the present application (including the aforementioned embodiment 1 and embodiment 2), the reflector 2 can be designed in combination with various factors such as the overall thickness of each reflection unit U, the thickness of a single film layer in the reflection unit U, the number of reflection periods T, etc., as long as it can meet actual needs, and the present application does not impose any restrictions on this.

[0075] The present application does not limit the shape of the above-mentioned reflection unit U, and it can be set as needed in practice.

[0076] For example, in some possible implementations, the reflective unit U may be a square (see Figure 2 ), rectangle, hexagon (reference Figure 5 )wait.

[0077] In addition, in the same reflector 2, the shapes of different reflective units U may be the same or different, and the present application does not impose any limitation on this. In practice, the shapes may be designed as required.

[0078] Of course, in order to improve the utilization rate of light, the multiple reflection units U in the reflector 2 can usually be arranged closely.

[0079] In addition, as shown in Reference 5, the present application does not limit the lateral size L of a single reflective unit U. For example, in some possible implementations, the lateral size L of the reflective unit U may be 10 nm to 1 mm. Optionally, in some possible implementations, the lateral size L of the reflective unit U is 100 nm to 100 μm.

[0080] It can be understood here that the lateral dimension L of the reflection unit U refers to the dimension between two edges (or two opposite edges) of the reflection unit U passing through the center point along any direction in the reflection plane.

[0081] The present application does not limit the specific materials used for the reflective layer a and the transmissive layer b in the reflective unit U.

[0082] Illustratively, the reflective layer a can be made of one or more materials such as Nb (niobium), Ni (nickel), Au (gold), Ru (ruthenium), Rh (rhodium), Mo (molybdenum), Cr (chromium), Co (cobalt), La (lanthanum), and W (tungsten), but is not limited thereto.

[0083] Illustratively, the transmission layer may be made of one or more materials such as Si (silicon), Be (beryllium), C (carbon), B (boron), B4C (boron carbide), Sr (strontium), Sc (scandium), etc., but is not limited thereto.

[0084] In practice, suitable materials can be selected for different wavebands to make the reflective layer a and the transmissive layer b.

[0085] For example, in some possible implementations, when the optical system adopts a coherent light source, the reflection layer a / transmission layer b can adopt Nb / Si (niobium / silicon), that is, the reflection layer a adopts Nb and the transmission layer b adopts Si, to ensure that the reflection unit U has a good reflectivity to the short-wave coherent light source.

[0086] For example, in some possible implementations, when the optical system uses an X-ray band light source, the reflective layer a / transmitting layer b can be made of Ru / Si (ruthenium / silicon), Mo / Be (molybdenum / beryllium), Cr / C (chromium / carbon), etc.

[0087] The present application does not impose any restrictions on the outer contour shape, surface shape, etc. of the reflector 2, and it can be set as needed in practice.

[0088] Illustratively, in some possible implementations, the outer contour of the reflector 2 may be a circle, an ellipse, a square or other irregular shapes.

[0089] As an illustration, in some possible implementations, the surface of the reflector 2 may be a plane, a spherical surface, or an aspherical surface (such as an aspherical surface that is rotationally symmetric about the Z axis).

[0090] It should be noted here that the overall curvature of the reflector 2 is relatively small, and the surface height difference between adjacent reflective units is very small compared with the area of ​​a single reflective unit. Therefore, the surface height difference between adjacent reflective units has a negligible effect on the overall surface shape of the reflector 2.

[0091] The decoherence principle of the reflector 2 in the optical system is further described below in conjunction with the reflective unit U in the reflector 2 .

[0092] Indicative, combined Figure 1 and Figure 3 , Figure 4As shown, the coherent light emitted by the coherent light source 1 is incident on the rotating reflector 2, and is divided into multiple sub-beams by multiple reflecting units U in the reflector 2. In this case, the phases of the multiple sub-beams reflected by the reflector 2 will change randomly (refer to the previous description), and the multiple sub-beams with randomly changed phases are further divided by the illumination system 3 and projected to the illumination area of ​​the illumination surface 4, so that the interference / speckle pattern formed in the illumination area can be continuously changed. When the change rate of the interference / speckle pattern reaches a certain level (fast enough) during the illumination time, the light intensity accumulation and uniformity in the illumination field can be achieved, thereby achieving the purpose of uniform light.

[0093] As shown, in some possible implementations, the illumination time can be set to 1 ms, and the rotation speed of the reflector 2 is 10000 rpm to 100000 rpm, such as 60000 rpm. In this case, the reflector 2 rotates 360 degrees within 1 ms, and forms a constantly changing interference / speckle pattern on the illumination surface 4 according to the number of pulses of the pulse light source, thereby achieving light intensity accumulation and uniformity in the illumination field.

[0094] It should be noted that the above embodiments are all illustrated by taking the rotating reflector 2 as an example, but the present application is not limited thereto.

[0095] In some other possible implementation methods, the reflector 2 can be controlled to move in a translational manner (such as moving along the X and Y axes), a shaking manner, or a combination of multiple movements, which can be specifically selected according to the setting position of the reflector 2, the application scenario, etc.

[0096] In addition, the size of the light beam incident on the reflector 2 can be equal to the size of the entire reflector 2 , or can be smaller than the size of the reflector 2 .

[0097] Schematically, in some possible implementations, the size of the light beam emitted by the coherent light source 1 is smaller than the size of the reflector 2. For example, the size of the light beam emitted by the coherent light source 1 can be half the size of the reflector 2, and the light beam is projected to the peripheral area (i.e., non-central area) of the reflector 2, thereby increasing the degree of phase randomization of the rotating central part.

[0098] The present application also provides a method Figure 3 The manufacturing method of the reflector 2 shown in Figure 6 As shown, the production method may include:

[0099] Step 11: providing a substrate 20.

[0100] Illustratively, the substrate 20 may be made of silicon (Si), quartz, microcrystalline glass, low expansion glass, etc., but is not limited thereto.

[0101] Step 12, in multiple reflection areas on the substrate 20, multiple reflection layers a and multiple transmission layers b are stacked alternately in sequence to form multiple reflection units U; wherein the reflection layers a and transmission layers b adjacently arranged in the reflection units U form a reflection period T; the surface roughness of the reflection units U is 0.05nm~1nm; there is a surface height difference (e.g., 0.1nm~10nm) between two adjacent reflection units U.

[0102] Regarding the specific configuration of the reflection unit U, the reflection layer a, and the transmission layer b, reference may be made to the corresponding description in the aforementioned embodiment 1, which will not be repeated here.

[0103] Illustratively, the above step 12 may include: using magnetron sputtering or atomic layer deposition to alternately deposit multiple reflective layers a and multiple transmissive layers b in a plurality of reflective regions on the substrate 20 to form a plurality of reflective units U.

[0104] Indicative, reference Figure 7 As shown, for the above-mentioned magnetron sputtering or atomic layer deposition method to form multiple reflective layers a and multiple transmissive layers b, the selective passage of the deposited material (such as C, Si, etc.) can be regulated by designing the mask M1. Figure 7 The white area of ​​the middle mask M1 is a transparent area, and the area outside the white area is a non-transparent area; the deposition material can be deposited from the transparent area to the substrate 20 to form a film layer (such as a reflective layer a and a transmissive layer b), but is blocked in the non-transparent area and cannot be deposited on the substrate 20. In practice, the deposition film layer can be regulated by controlling the deposition speed, deposition time, etc.

[0105] In addition, since the thicknesses of the reflective layer a and the transmissive layer b in different reflective units U in the present application are not completely the same, when actually manufacturing the reflective layer a and the transmissive layer b, a plurality of mask plates M1 with different mask patterns can be used, for example, Figure 8 Two different masks are used to adjust the type and thickness of the deposited film layers in different areas, thereby completing the production of multiple reflection units U in the reflector 2.

[0106] The present application also provides a method Figure 4 The manufacturing method of the reflector 2 shown in Fig. 9 As shown, the production method may include:

[0107] Step 21: providing a substrate 20.

[0108] Step 22, in multiple reflection areas on the substrate 20, multiple reflection layers a and multiple transmission layers b are stacked alternately in sequence to form multiple reflection units U; wherein the reflection layers a and transmission layers b adjacently arranged in the reflection unit U form a reflection period T; the surface roughness of the reflection unit U is 0.05nm~1nm; the surface height difference between two adjacent reflection units is less than 0.5nm, and the thickness of the reflection period T in two adjacent reflection units U is not exactly the same.

[0109] For the specific settings of the reflection unit U, the reflection layer a, and the transmission layer b, please refer to the corresponding description in the aforementioned embodiment 2; for the relevant production instructions, please refer to the relevant instructions in the previous steps 11 and 12, which will not be repeated here.

[0110] 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. A reflector, It is characterized in that It comprises a substrate and a plurality of reflecting units arranged on the substrate; Each of the reflection units comprises: a plurality of reflection layers and a plurality of transmission layers which are alternately stacked in sequence; wherein the reflection layers and the transmission layers which are adjacently arranged form a reflection period; The surface roughness of the reflection unit is 0.05nm to 1nm; The surface height difference between two adjacent reflection units; and / or the thickness of the reflection period in two adjacent reflection units is not completely the same.

2. The reflector according to claim 1, It is characterized in that The surface height difference between two adjacent reflection units is 0.1 nm to 10 nm.

3. The reflector according to claim 2, It is characterized in that In a single reflection unit, all the reflection layers have the same thickness, and all the transmission layers have the same thickness.

4. The reflector according to claim 1, It is characterized in that A surface height difference between two adjacent reflection units is less than 0.5 nm, and thicknesses of the reflection periods in two adjacent reflection units are not completely the same.

5. The reflector according to claim 4, It is characterized in that The thickness difference between the reflection periods in two adjacent reflection units is 0.1 nm to 1 nm.

6. The reflector according to any one of claims 1 to 5, It is characterized in that The reflection unit is provided with 10 to 100 reflection periods.

7. The reflector according to any one of claims 1 to 6, It is characterized in that The transmission layer includes one or more of Si, Be, C, B, B4C, Sr, and Sc; The reflective layer includes one or more of Nb, Ni, Au, Ru, Rh, Mo, Cr, Co, La, and W.

8. The reflector according to any one of claims 1 to 7, It is characterized in that The lateral size of the reflection unit is 10 nm to 1 mm.

9. The reflector according to any one of claims 1 to 8, It is characterized in that The reflector has a plane, a spherical surface or an aspherical surface.

10. An optical system, It is characterized in that comprising a coherent light source, an illumination system and at least one reflector as claimed in any one of claims 1 to 9; The light beam emitted by the coherent light source is divided into a plurality of sub-beams by the lighting system and then projected onto the lighting surface; The reflector is arranged on the optical path from the coherent light source to the illumination surface.

11. A method for manufacturing a reflector, It is characterized in that include: providing a substrate; A plurality of reflective layers and a plurality of transmissive layers are alternately stacked in sequence in a plurality of reflective regions on the substrate to form a plurality of reflective units; wherein the reflective layers and the transmissive layers adjacently arranged in the reflective units form a reflective period; the surface roughness of the reflective units is 0.05 nm to 1 nm; the surface height difference between two adjacent reflective units; and / or the thickness of the reflective period in two adjacent reflective units is not completely the same.

12. The method for manufacturing a reflector according to claim 11, It is characterized in that include The different reflection areas on the substrate are alternately formed into a plurality of reflection layers and a plurality of transmission layers, comprising: By adopting the method of magnetron sputtering or atomic layer deposition, multiple reflective layers and multiple transmissive layers are alternately deposited in different reflective regions on the substrate.

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