Gradual change blazed surface grating

Abstract

The application discloses a gradually-changing blazed surface grating, which comprises a plurality of gradually-changing blazed surfaces, and the size of the corresponding blazed angle of each gradually-changing blazed surface presents a gradually-increasing trend from one region to another region in the length direction of the gradually-changing blazed surface. The application can solve the problem of narrow available wavelength range under the condition of greater than a certain diffraction efficiency required by a grating device, and realize higher diffraction efficiency of the grating in a wider wavelength range.

Description

Technical Field

[0001] This invention relates to the field of grating technology, and in particular to a gradient blazed surface grating. Background Technology

[0002] A blazed grating is a special type of reflective or transmissive diffraction grating. For a blazed grating with a single blaze angle, according to the grating equation, mλ = d(sinα) - sin(β), where d is the grating constant, α is the incident angle, β is the diffraction angle, m is the diffraction order, and λ is the blaze wavelength at the m-th order. (See attached diagram.) Figure 1 As shown, given the incident direction of the incident light, the blaze angle of the grating, and the required diffraction order, the blaze wavelength in the exit direction can be determined. The blaze wavelength corresponds to the maximum value of the grating's diffraction efficiency. As the incident wavelength deviates from the blaze wavelength, the diffraction efficiency gradually decreases. This means that instruments using gratings can only use a relatively narrow band range on both sides of the blaze wavelength, because the diffraction efficiency meets the design requirements within this range, such as... Figure 2 As shown, this is the curve of the -2nd order diffraction efficiency of a grating with a period of 7 micrometers and a single blaze angle of 45° under collimated incident conditions, as a function of incident wavelength. It can be seen that the diffraction efficiency reaches its peak at an incident wavelength of 5 micrometers, and the diffraction efficiency decreases rapidly as the incident wavelength increases and decreases. To meet the requirement of a diffraction efficiency greater than 30%, the usable wavelength range of this single blaze angle grating under collimated incident conditions is 3.93 to 5.57 micrometers.

[0003] Currently, there are two main methods to broaden the diffraction efficiency band of gratings. One method is to first fabricate two gratings with different blaze angles, and then splice these two gratings together (e.g., Figure 3a Another method is to fabricate a double blaze angle within one grating period (such as...). Figure 3b (As shown).

[0004] The method of fabricating two gratings with different blaze angles first and then splicing them together has the following three problems: 1. Conventional methods are not entirely applicable in grating splicing, and previous related research is still incomplete; 2. Using parallel splicing to fabricate variable-pitch gratings may improve the curvature of the grating lines, but related research is lacking; 3. Double-blazed gratings have good broadband diffraction efficiency, and mechanical splicing could be considered for fabricating such gratings, but similarly, there is a lack of reports on this. Another method of fabricating double blaze angles within one grating period also suffers from excessive fabrication difficulty and relatively poor fabrication accuracy.

[0005] In addition, for the two methods mentioned above to improve the diffraction efficiency of gratings in different wavelength ranges, such as... Figure 4As shown, the diffraction efficiency of the entire grating is the average of the diffraction efficiencies of the two gratings at different wavelengths. It can be seen that there is a range of decreasing diffraction efficiency between the two peak values ​​(e.g., ...). Figure 4 (Approximately 350 nanometers). This presents a contradiction: if the spacing between the two blaze wavelengths is too large, a region with low diffraction efficiency will appear between them; if the spacing is too small, the ability to blaze over a wide band will be lost. Therefore, it is necessary to invent a grating for blazing over a wide band. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a graded blazed surface grating that can solve the problem of a narrow usable wavelength range required by grating devices for diffraction efficiencies greater than a certain value, and achieve a grating with high diffraction efficiency over a wider wavelength range.

[0007] According to an embodiment of the present invention, a gradient blaze grating includes a plurality of gradient blaze surfaces, wherein the size of the blaze angle corresponding to each gradient blaze surface gradually increases from one region to another along the length direction of the gradient blaze surface.

[0008] For a grating optical system with a fixed grating period and incident angle, a change in the blaze angle directly corresponds to a change in the blaze wavelength. The gradient blaze grating of this embodiment is equivalent to the superposition of countless fixed blaze angle gratings. According to the grating equation, the larger the blaze angle, the larger the blaze wavelength. That is, polychromatic light will have a blaze wavelength in one region of the gradient blaze surface, and the closer the light is to another region of the gradient blaze surface, the longer the blaze wavelength. The diffraction efficiency of the grating is the average of the diffraction efficiencies of its various parts. Within the range of blaze wavelengths corresponding to the minimum and maximum blaze angles of the gradient blaze grating in this embodiment, the diffraction efficiency exhibits a relatively gradual change. This avoids the problem of a narrow blaze wavelength range in single-blaze angle gratings and also avoids the problem of a drastic drop in diffraction efficiency between two blaze wavelengths in double-blaze angle gratings.

[0009] According to the embodiments of the present invention, the gradient blazed surface grating can solve the problem of the narrow usable wavelength range required by grating devices when the diffraction efficiency is greater than a certain value, and realize that the grating has a high diffraction efficiency over a wider wavelength range.

[0010] In some embodiments, the size of the scintillation angle corresponding to each of the gradient scintillation surfaces increases continuously from one end to the other along the length direction of the gradient scintillation surface.

[0011] In some embodiments, the plurality of gradient shimmering surfaces are all identical.

[0012] In some embodiments, the gradient shimmering grating is made of metal or non-metal.

[0013] In some embodiments, the gradient luminous grating is a non-spliced, one-piece molded part.

[0014] In some embodiments, the gradient blazed surface grating is obtained by processing the base workpiece material using a high-frequency non-resonant vibration cutting machining system and a triangular trajectory forming method.

[0015] In some embodiments, the high-frequency non-resonant vibration cutting system includes a three-axis ultra-precision motion platform, a high-frequency non-resonant vibration device, a cutting tool, an auxiliary tooling fixture, and a power drive system for the vibration device; wherein, the three-axis ultra-precision motion platform is used to mount the base workpiece material; the cutting tool is mounted on the high-frequency non-resonant vibration device, the high-frequency non-resonant vibration device is mounted on the auxiliary tooling fixture, and the power drive system for the vibration device drives the high-frequency non-resonant vibration device.

[0016] In some embodiments, the power drive system of the vibration device includes a signal generator and a power amplifier; the method for forming the triangular trajectory is to decompose the displacement of the triangular trajectory in the X and Y directions respectively, then use the signal generator to fit the amplitude-time relationship in the X and Y directions, then use the signal generator to generate the result and transmit it to the piezoelectric stack through the power amplifier, and finally use the tool to realize the expected triangular trajectory.

[0017] In some embodiments, the cutting tool is a diamond cutting tool, the rake angle of the cutting tool is 0°, and the clearance angle of the cutting tool is 30°, which is greater than the minimum value of the grating bottom angle. In some embodiments, the design is carried out using the following method:

[0018] Determine the incident wavelength range according to the instrument's operating wavelength requirements;

[0019] Determine the incident angle and diffraction angle based on the instrument's optical path design;

[0020] Choose the appropriate diffraction secondary of the light used, and select the grating period according to the processing capability;

[0021] The incident wavelength range, the incident angle, the diffraction angle, the diffraction secondary, and the grating period are all made to satisfy the grating equation.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0024] Figure 1 This is a schematic diagram illustrating the principle of the grating equation;

[0025] Figure 2 This is a schematic diagram showing the variation of the -2nd order diffraction efficiency with the incident wavelength under collimated incident conditions for a grating with a period of 7 micrometers and a single blaze angle of 45 degrees.

[0026] Figure 3a This is a schematic diagram of an existing double blazed angle grating;

[0027] Figure 3b Here is a schematic diagram of a double-angle blazed grating;

[0028] Figure 4 The diagram shows the diffraction efficiency of a current double blazed angle grating as a function of incident wavelength.

[0029] Figure 5a The present invention is a schematic diagram of splicing error of a dual-blazed-angle partitioned grating;

[0030] Figure 5b This is a schematic diagram of an ideally assembled dual-blazed-angle partitioned grating;

[0031] Figure 6 This is a schematic diagram of a gradient glazed surface grating according to an embodiment of the present invention;

[0032] Figure 7 This is a simulation experiment diagram of the diffraction efficiency according to an embodiment of the present invention;

[0033] Figure 8a This is a schematic diagram of the high-frequency non-resonant vibration cutting system used in the gradient flashing grating of this invention.

[0034] Figure 8b This is a schematic diagram of the method for forming a triangular trajectory for a gradient glitter grating according to an embodiment of the present invention;

[0035] Figure 9a This is a tool trajectory diagram during the machining process of a gradient flashing grating according to an embodiment of the present invention;

[0036] Figure 9b It is a topographic image of a gradient glitter grating produced by using a high-frequency non-resonant vibration cutting system and a triangular trajectory forming method.

[0037] Figure Labels

[0038] Gradient blazing grating 1000; Gradient blazing surface 1; High-frequency non-resonant vibration cutting system 2; Auxiliary tooling fixture 202; Cutting tool 203; High-frequency non-resonant vibration device 204; Signal generator 205; Power amplifier 206; Base workpiece material 3. Detailed Implementation

[0039] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0040] The following is combined with Figures 6 to 9b This invention describes a gradient blazed surface grating 1000 according to an embodiment of the present invention.

[0041] like Figure 6 As shown, the gradient blaze grating 1000 according to an embodiment of the present invention includes a plurality of gradient blaze surfaces 1. The size of the blaze angle corresponding to each gradient blaze surface 1 gradually increases from one region to another along the length direction 0 of the gradient blaze surface 1. For example, the size of the blaze angle corresponding to each gradient blaze surface 1 increases from one end (which can be understood as one region) to the other end (which can be understood as another region) of the gradient blaze surface 1. The size of the blaze angle corresponding to one end of each gradient blaze surface 1 is δ1, and the size of the blaze angle corresponding to the other end of each gradient blaze surface 1 is δ2, where δ2 is greater than δ1.

[0042] For a grating optical system with a fixed grating period and incident angle, a change in the blaze angle directly corresponds to a change in the blaze wavelength. The gradient blaze grating 1000 of this embodiment is equivalent to the superposition of countless gratings with fixed blaze angles. According to the grating equation, the larger the blaze angle, the larger the blaze wavelength. That is to say, as... Figure 6 As shown, polychromatic light has a blaze wavelength at one end of the gradient blaze surface 1, and the closer the light is to the other end of the gradient blaze surface 1, the longer the blaze wavelength. The diffraction efficiency of the grating is the average of the diffraction efficiencies of each part of the grating. Within the range of blaze wavelengths corresponding to the minimum and maximum blaze angles of the gradient blaze surface grating 1000 in this embodiment of the invention, the diffraction efficiency exhibits a relatively gradual change. This avoids the problem of a narrow blaze wavelength range in a single blaze angle grating, and also avoids the problem of a sharp drop in diffraction efficiency between two blaze wavelengths in a double blaze angle grating.

[0043] Figure 7This is a simulation experiment diagram of the diffraction efficiency of an embodiment of the present invention, showing the variation of the diffraction efficiency of three gratings with the incident light wavelength. The wavelength range with a diffraction efficiency greater than 30% is defined as the usable wavelength range. It can be seen that curve A represents the diffraction efficiency of an existing single blaze angle (45°) diffraction grating. This grating reaches its peak diffraction efficiency under incident light at a wavelength of 5 micrometers, but the diffraction efficiency decreases rapidly on both sides of the blaze wavelength, with a usable incident wavelength range of 3.93-5.57 micrometers. Curve B represents the diffraction efficiency of an existing double blaze angle (30° and 60°) grating, showing a significant decrease in diffraction efficiency between the two blaze wavelengths. The usable incident wavelength range for this double blaze angle (30° and 60°) grating is 2.86-4.57 micrometers. Curve C represents a gradient blazed surface grating 1000 (blazed angle from 30° to 75°) according to an embodiment of the present invention. It can be seen that the diffraction efficiency exhibits a smooth and uniform state over a wide wavelength range, with an incident wavelength range of 3.12-6.11 micrometers, which is significantly greater than that of existing single blazed angle (45°) diffraction gratings and existing double blazed angle (30° and 60°) gratings.

[0044] According to the embodiment of the present invention, the gradient blazed surface grating 1000 can solve the problem of the narrow usable wavelength range required by the grating device when the diffraction efficiency is greater than a certain value, and realize that the grating has a high diffraction efficiency over a wider wavelength range.

[0045] In some embodiments, the size of the blaze angle corresponding to each gradient blaze surface 1 increases continuously from one end of the gradient blaze surface 1 to the other end. This allows the gradient blaze surface grating 1000 of the present invention to have high diffraction efficiency over a wider wavelength range.

[0046] In some embodiments, the plurality of gradient blazed surfaces 1 are all identical. This allows the gradient blazed surface grating 1000 of the present invention to have high diffraction efficiency over a wider wavelength range.

[0047] In some embodiments, the gradient shimmering grating 1000 is made of metal or non-metal, which can be selected according to actual needs. For example, non-metals can be made of resin or glass, etc.

[0048] In some embodiments, the gradient blazed surface grating 1000 is a non-spliced, integrally formed part. That is, the gradient blazed surface grating 1000 in this embodiment is an integrally formed part processed on a substrate working material 3. In this way, not only is the diffraction efficiency improved compared to the traditional double blazed angle grating, but many difficulties in the splicing process of the traditional double blazed angle grating are also avoided. For example, for the double blazed angle partitioned grating, the groove depths of different groove shapes may not be at the same depth (e.g., Figure 5aAs shown), ideally, the centerlines of different blaze angles in a double blaze angle grating should be aligned (e.g., Figure 5b (As shown). Figure 5a Under certain conditions, a fixed phase difference will exist between the diffracted beams of the same incident light, and this difference is related to the difference in the depth of the slots in the two gratings. Figure 5b There is no phase difference between the diffracted light from the two gratings, but for the gradient blazed surface grating 1000 of this embodiment of the invention, it is easy to achieve no phase difference.

[0049] In some embodiments, such as Figure 8a and 8b As shown, the gradient blazed surface grating 1000 is obtained by machining one side of the substrate workpiece material 3 using a high-frequency non-resonant vibration cutting machining system 2 and a triangular trajectory forming method. Specifically, the tool 203 of the high-frequency non-resonant vibration cutting machining system 2 travels along a triangular trajectory in the XY plane, cutting off the material portion of the substrate workpiece material 3 within the triangular trajectory, thereby machining a groove; then, the tool 203 steps a certain distance and repeats the triangular trajectory forming method to machine another groove, and so on, until the gradient blazed surface grating 1000 of this embodiment of the invention is obtained.

[0050] In some embodiments, such as Figure 8a As shown, the high-frequency non-resonant vibration cutting system 2 includes a three-axis ultra-precision motion platform (not shown), a high-frequency non-resonant vibration device 204, a cutting tool 203, an auxiliary tooling fixture 202, and a power drive system for the vibration device. The three-axis ultra-precision motion platform is used to mount the base workpiece material 3. The cutting tool 203 is mounted on the high-frequency non-resonant vibration device 204, which is mounted on the auxiliary tooling fixture 202. The power drive system drives the high-frequency non-resonant vibration device 204. The power drive system includes a signal generator 205 and a power amplifier 206 electrically connected to the signal generator 205. The signal generator 205 uses LabVIEW virtual instrument software combined with an NI data acquisition card. During operation, the signal generator 205 acquires signals generated in the host computer and generates results, which are amplified by the power amplifier, transmitted to the piezoelectric stack, and finally driven by the cutting tool 203 to achieve the expected trajectory. The final cutting tool 203 trajectory (via...) Figure 8a The surface morphology of the laser sensor head (obtained from the laser sensor head) and the surface morphology of the processed grating are as follows: Figure 9a and Figure 9b As shown.

[0051] In some embodiments, the method for forming a triangle trajectory involves decomposing the displacement of the triangle trajectory in the X and Y directions, fitting the amplitude-time relationship in the X and Y directions using a signal generator 205, generating a result using the signal generator 205, transmitting it to the piezoelectric stack via a power amplifier 206, and finally cutting the triangle trajectory using a tool 203.

[0052] In some embodiments, the tool 203 is a diamond tool with a rake angle of 0° and a clearance angle of 30°, which is greater than the minimum value of the grating bottom angle. Since the material, rake angle, and clearance angle of the tool 203 have different effects on the machining accuracy of the grating, using a diamond tool with a rake angle of 0° or a negative rake angle, a clearance angle of 30°, and a tool tip radius of 0.5mm results in high machining accuracy. Furthermore, having a clearance angle greater than the minimum value of the grating bottom angle can avoid interference between the tool and the substrate workpiece material during machining.

[0053] In some embodiments, the gradient radiant grating 1000 is designed using the following method:

[0054] The incident wavelength range is determined according to the instrument's operating wavelength requirements. That is, the incident wavelength range of the graded blazed grating 1000 is determined according to the operating wavelength of the instrument to which the graded blazed grating 1000 is applied, such as a spectrometer or an infrared remote sensor. In other words, the instrument's operating wavelength is the incident wavelength of the grating.

[0055] The incident angle and diffraction angle are determined according to the optical path design of the instrument. That is, the incident angle and diffraction angle of the incident wave relative to the required graded blazed grating 1000 are determined according to the optical path design of the instrument to which the graded blazed grating 1000 is applied, such as a spectrometer or an infrared remote sensor.

[0056] Choose the appropriate diffraction secondary of the incident wave and select the grating period based on the processing capability.

[0057] By ensuring that the incident wavelength range, incident angle, diffraction angle, diffraction secondary, and grating period are all consistent with the grating equation, the required gradient blazed surface grating 1000 can be designed.

[0058] It should be noted that in the structural design of the graded blazed surface grating 1000, a blazed surface with a graded blaze angle needs to be designed. According to the grating equation mλ=d(sinα)-sin(β)), where d is the grating constant, α is the incident angle, β is the diffraction angle, m is the diffraction order, and λ is the blaze wavelength at the m-order, it is necessary to determine the wavelength range of the graded blazed surface grating 1000 in its working state. The following factors affect the working wavelength range and diffraction efficiency of the graded blazed surface grating 1000: grating period, blaze angle variation range, grating height, and incident angle.

[0059] First, the wavelength range for which the grating will be used should be determined. For a grating with a fixed period, a small incident angle and small diffraction angle can be used in a shorter wavelength range (e.g., an incident angle of 10° and a grating blaze angle of 45°). If it is desired to increase the operating wavelength range of the grating, according to the grating equation, the incident angle and the grating blaze angle should be designed to be larger (e.g., an incident angle of 45° and a grating blaze angle of 45°). Second, the blaze wavelength corresponding to the blaze angle should be close to that of the grating and within the operating wavelength range of the grating. Then, the blaze angle should vary within a reasonable range; if the blaze angle varies too widely, the overall diffraction efficiency of the grating will decrease. Finally, these factors should also be considered during the grating design process.

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A gradient blazed surface grating, characterized in that, The device includes multiple gradient glitter surfaces, each with a glitter angle that gradually increases from one region to another along its length. The length direction of the gradient glitter surface refers to its own extension direction, and this direction is distinct from the periodic arrangement direction of the multiple gradient glitter surfaces. Along the length direction of the gradient glitter surface, each surface extends continuously from one end to the other. The glitter angle at one end of each surface is δ1, and the glitter angle at the other end is δ2, where δ2 is greater than δ1. The multiple gradient glitter surfaces are arranged parallel to each other and at equal intervals on the same side of the substrate, and the periodic arrangement direction is linear.

2. The gradient blazed surface grating according to claim 1, characterized in that, The size of the scintillation angle corresponding to each of the gradient scintillation surfaces shows a continuous increasing trend from one end to the other along the length direction of the gradient scintillation surface.

3. The gradient blazed surface grating according to claim 1, characterized in that, All of the gradient shimmering surfaces are identical.

4. The gradient blazed surface grating according to claim 1, characterized in that, The material of the gradient luminous grating is either metal or non-metal.

5. The gradient blazed surface grating according to claim 1, characterized in that, The gradient radiant grating is a non-spliced, one-piece molded part.

6. The gradient blazed surface grating according to any one of claims 1-5, characterized in that, The gradient blazed surface grating is obtained by processing the base workpiece material using a high-frequency non-resonant vibration cutting system and a triangular trajectory forming method.

7. The gradient blazed surface grating according to claim 6, characterized in that, The high-frequency non-resonant vibration cutting system includes a three-axis ultra-precision motion platform, a high-frequency non-resonant vibration device, a cutting tool, an auxiliary tooling fixture, and a power drive system for the vibration device. The three-axis ultra-precision motion platform is used to mount the base workpiece material. The cutting tool is mounted on the high-frequency non-resonant vibration device, which is mounted on the auxiliary tooling fixture. The power drive system for the vibration device drives the high-frequency non-resonant vibration device.

8. The gradient blazed surface grating according to claim 7, characterized in that, The power drive system of the vibration device includes a signal generator and a power amplifier; the method for forming the triangular trajectory is to decompose the displacement of the triangular trajectory in the X and Y directions respectively, then use the signal generator to fit the amplitude-time relationship in the X and Y directions, then use the signal generator to generate the result and transmit it to the piezoelectric stack through the power amplifier, and finally use the tool to realize the expected triangular trajectory.

9. The gradient blazed surface grating according to claim 7, characterized in that, The cutting tool is a diamond tool, and the rake angle of the cutting tool is 0°. The back angle of the cutting tool is 30°. And it is greater than the minimum value of the bottom corner of the grating.

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