A method and device for detecting the deflection angle of a DMD micromirror

Abstract

The present invention provides a method and device for detecting the deflection angle of a micromirror of a DMD, comprising: S1, a DMD chip, an aperture I, an aperture II and a laser emitter are placed in sequence; S2, the power supply of the DMD chip is disconnected, the laser emitter emits a first laser beam that passes through apertures II and aperture I and hits the central area of ​​the DMD chip, and the light reflected by the DMD returns to apertures I and aperture II along the original path; S3, the DMD chip is powered on and a checkerboard pattern is uploaded; S4, a second laser beam is introduced; S5, a reflector is introduced so that the first laser beam and the second laser beam are aligned with each other. The light spots formed by the two laser beams on the reflector overlap, and the incident angle of the second laser beam incident on the DMD chip is recorded as θ; S6, introduce an observation screen; S7, fine-tune the reflector so that the center of the chessboard image on the observation screen is five uniform bright spots; S8, measure the incident angle θ; S9, calculate the micromirror deflection angle θ0 of the DMD chip, θ0=0.5θ. The DMD micromirror deflection angle detection method and device of the present invention have the advantages of accurate detection of the micromirror deflection angle of the DMD and simple operation process.

Description

Technical Field

[0001] The invention belongs to the field of optical technology, and in particular relates to a method and a device for detecting a micromirror deflection angle of a DMD. Background Art

[0002] With the development of information technology, the amount of data generated is growing explosively, and the demand for data storage density and data conversion rate is increasing sharply. Traditional data storage technology has been difficult to meet the needs of data growth, and a new generation of storage technology is in urgent need of development. As a three-dimensional storage technology, holographic storage technology has ultra-high theoretical storage density and ultra-fast data conversion rate, and is considered to be a strong competitor for the new generation of storage technology.

[0003] Currently, the amplitude-type holographic storage system is one of the holographic storage systems that people mainly study, because the CCD detector can directly detect intensity information, and the amplitude-type spatial light modulator, such as DMD (digital micromirror device), can provide a very high refresh rate, which can improve the data conversion rate.

[0004] Among them, the Digital Micromirror Device (DMD) is a micro-opto-electromechanical system, which consists of a two-dimensional micro-mirror array. It uses the monolithic manufacturing technology of the CMOS process to integrate the micro-mirror optical switch array into a microchip. Each micro-mirror can flip between two states of positive and negative 12 degrees around the axis independently, so it can modulate the amplitude of the light field. Each optical switch has a mirror connected to a memory unit. By controlling the charge state of the storage unit, the rotational motion and time domain response of the micro-mirror around the fixed axis are changed, thereby realizing the modulation of the angle direction and dead time of the light reflected and emitted by each unit. DMD can realize the modulation and gating of the space of light, and the time required for gating is in the microsecond level, and there is no mechanical movement of the device during the modulation process, but DMD can only realize the modulation of the light beam in the two-dimensional plane of space, and cannot realize the encoding and modulation of the spatial propagation angle.

[0005] In the laser direct imaging system, the long side direction of the DMD installation surface and the exposure stepping direction theoretically need to maintain an ideal working angle θ, so that there is no vertical misalignment error between the left and right adjacent strips of the exposed pattern. In fact, after the DMD is installed and fixed, there is always a working angle error e between the actual assembly angle θ' of the DMD and the ideal working angle θ, e = θ'-θ. In order to calculate the size of the error, it is necessary to measure the actual assembly angle θ' of the DMD, that is, the deflection angle of the micromirror, and then combine it with the ideal working angle θ to obtain the working angle error e.

[0006] At present, the world-renowned DMD manufacturer Texas Instruments (TI) allows an angle error range of ±1° when producing DMDs. Although this can meet most basic applications of DMDs, some high-precision application fields, such as holographic storage, maskless lithography, and super-resolution microscopy, have relatively high requirements for the angle error of DMDs. In order to accurately measure the angle error of DMDs, it is necessary to provide a more accurate method for detecting the micromirror deflection angle of DMDs.

[0007] At present, although some DMD micromirror deflection angle detection systems have appeared in the market, most of them have the disadvantages of complex detection device structure, high cost, low detection accuracy, cumbersome operation, and difficulty in mastering. Therefore, providing a DMD micromirror deflection angle detection system with simple structure, easy implementation, accurate detection of DMD micromirror deflection angle, and simple operation process is one of the technical problems that technicians in this field need to solve urgently. Summary of the invention

[0008] The purpose of the present invention is to provide a method and device for detecting the deflection angle of a micromirror of a DMD in order to solve the above-mentioned technical problems, so as to achieve accurate and convenient detection of the deflection angle of the micromirror of the DMD.

[0009] In view of this, the present invention provides a method for detecting a micromirror deflection angle of a DMD, comprising the steps of:

[0010] S1, place the DMD chip, aperture I, aperture II and laser emitter in sequence so that their center points are on the same straight line;

[0011] S2, when the power of the DMD chip is disconnected, the position of the laser emitter is adjusted so that the first laser beam emitted by the laser emitter passes through the aperture II and the aperture I at the same time and hits the central area of ​​the DMD chip, and the fixed angle of the DMD is adjusted so that the light reflected by the DMD returns to the aperture I and the aperture II along the original path;

[0012] S3, powering on the DMD chip and uploading a checkerboard pattern;

[0013] S4, introducing a second laser beam so that it is incident in a direction perpendicular to the first laser beam;

[0014] S5, introducing a reflector at one side of the first laser beam, adjusting the position and direction of the reflector so that the light spots formed on the reflector by the first laser beam and the second laser beam overlap, at which time the reflected light of the second laser beam will be incident on the DMD chip along a certain angle, and the incident angle of the reflected light of the second laser beam on the DMD chip is recorded as θ;

[0015] S6, introducing an observation screen between the DMD chip and the aperture I, and observing a chessboard image formed on the observation screen;

[0016] S7, fine-tuning the position and direction of the reflector so that the center of the chessboard image formed on the observation screen is five uniform bright spots;

[0017] S8, measuring the incident angle θ of the reflected light of the second laser beam incident on the DMD chip at this time;

[0018] S9, calculating the micromirror deflection angle θ of the DMD chip according to the incident angle θ measured in step S8 0 , where θ 0 =0.5θ.

[0019] Furthermore, in step S1, the center points of the DMD chip, aperture I, aperture II and laser emitter are located on the same horizontal straight line.

[0020] Furthermore, the distance between the DMD chip and aperture I is recorded as h1, the distance between aperture I and aperture II is recorded as h2, and the distance between aperture II and the laser emitter is recorded as h3, then, h1<h3<h2.

[0021] Furthermore, the second laser beam is a green laser beam.

[0022] Furthermore, the second laser beam is incident on the reflector from top to bottom in a vertical direction, and the reflector is located at a lower side of the first laser beam.

[0023] Furthermore, the reflector is located between the DMD chip and the aperture I.

[0024] Furthermore, the observation screen is arranged in parallel with the aperture I and the aperture II, the observation screen and the center points of the aperture I and the aperture II are located on the same straight line, and the observation screen is located between the DMD chip and the aperture I.

[0025] Furthermore, in step S7, the five bright spots located at the center of the chessboard image are determined according to the following method:

[0026] First, the geometric center point of the chessboard image formed on the observation screen is determined, and then a central circle is made with the geometric center point as the center. There is a bright spot at the center of the central circle, and the central circle passes through four bright spots that are closest to the geometric center point and are distributed in a cross shape, which together constitute the five bright spots located in the center of the chessboard image.

[0027] Furthermore, in step S7, when adjusting the position and direction of the reflector, the changes of the five bright spots in the center of the chessboard image formed on the observation screen are observed simultaneously. When the position and direction of the reflector are not adjusted to the specified position, among the five bright spots in the center of the chessboard image formed on the observation screen, the position of the brightest spot with the highest brightness is not at the center of the center circle; when the position and direction of the reflector are adjusted to the specified position, the brightest spot with the highest brightness is at the center of the center circle.

[0028] A device for detecting a deflection angle of a micromirror of a DMD, wherein the device detects the deflection angle of the micromirror of the DMD by using the above-mentioned detection method.

[0029] The method and device for detecting the deflection angle of a micromirror of a DMD of the present invention have the advantages of simple structure, easy implementation, accurate detection of the deflection angle of a micromirror of a DMD, and simple operation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the arrangement of the DMD chip, aperture I, aperture II and laser emitter of the present invention;

[0031] Figure 2 It is a schematic diagram of the arrangement of the observation screen and the reflector of the present invention;

[0032] Figure 3 is a schematic diagram of the checkerboard pattern of the present invention;

[0033] Figure 4 is an example of a chessboard image formed on the observation screen of the present invention;

[0034] Figure 5 is another example of the chessboard image formed on the viewing screen of the present invention.

[0035] The symbols in the figure are:

[0036] 1. DMD chip; 2. Aperture I; 3. Aperture II; 4. Laser emitter; 5. First laser beam; 6. Reflector; 7. Checkerboard pattern; 8. Observation screen; 9. Second laser beam; 10. Bright spot; 11. Center circle. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0038] In the description of the present application, it should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. For ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0039] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0040] It should be noted that, in the description of the present application, the orientation or positional relationship indicated by terms such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise stated, these orientation words do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application; the orientation words "inside and outside" refer to the inside and outside relative to the contour of each component itself.

[0041] It should be noted that, in the present application, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises one..." does not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be noted that the scope of the method and device in the embodiment of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0042] like Figures 1 to 4 As shown, a method for detecting the deflection angle of a micromirror of a DMD comprises the steps of:

[0043] S1, place the DMD chip 1, aperture I 2, aperture II 3 and laser emitter 4 in sequence so that their center points are on the same straight line;

[0044] S2, when the power of the DMD chip 1 is disconnected, the position of the laser emitter 4 is adjusted so that the first laser beam 5 emitted by the laser emitter 4 passes through the aperture II 3 and the aperture I 2 at the same time and hits the central area of ​​the DMD chip 1, and the fixed angle of the DMD is adjusted so that the light reflected by the DMD returns to the aperture I and the aperture II along the original path;

[0045] S3, powering on the DMD chip 1 and uploading the checkerboard pattern 7;

[0046] S4, introducing a second laser beam 9 so that it is incident in a direction perpendicular to the first laser beam 5;

[0047] S5, introducing a reflector 6 on one side of the first laser beam 5, adjusting the position and direction of the reflector 6 so that the light spots formed on the reflector 6 by the first laser beam 5 and the second laser beam 9 are substantially overlapped, at which point the reflected light of the second laser beam 9 will be incident on the DMD chip 1 along a certain angle, and the incident angle of the reflected light of the second laser beam 9 on the DMD chip 1 is recorded as θ;

[0048] S6, introducing an observation screen 8 between the DMD chip 1 and the aperture Ⅰ 2, and observing a chessboard image formed on the observation screen 8;

[0049] S7, fine-tuning the position and direction of the reflector 6 so that the center of the chessboard image formed on the observation screen 8 is five uniform bright spots 10;

[0050] S8, measuring the incident angle θ of the reflected light of the second laser beam 9 incident on the DMD chip 1 at this time;

[0051] S9, calculating the micromirror deflection angle θ of the DMD chip 1 according to the incident angle θ measured in step S8 0 , where θ 0 =0.5θ.

[0052] Furthermore, the DMD chip 1, aperture I 2 and aperture II 3 are arranged in parallel.

[0053] Preferably, in step S1, the DMD chip 1, aperture I 2, aperture II 3 and laser emitter 4 may be placed in sequence so that their center points are located on the same horizontal straight line.

[0054] Furthermore, the distance between the DMD chip 1 and the aperture I2 is recorded as h1, the distance between the aperture I2 and the aperture II3 is recorded as h2, and the distance between the aperture II3 and the laser emitter 4 is recorded as h3, then, h1<h3<h2.

[0055] Furthermore, the ratio of h2 / h3 is 3-1.5; the ratio of h2 / h1 is 5-12.

[0056] Preferably, the laser emitter 4 is a red light laser, and the light it emits is red light, that is, the first laser beam 5 is a red laser beam.

[0057] Furthermore, in the step S2, the wavelength of the first laser beam 5 emitted by the laser emitter 4 is 680-740 nm.

[0058] Furthermore, in step S3, the checkerboard pattern 7 is a checkerboard pattern composed of black and white squares.

[0059] Furthermore, in the step S3, uploading the checkerboard pattern 7 means marking the checkerboard pattern 7 on the Fourier plane.

[0060] Furthermore, in the step S4, the second laser beam 9 is a green laser beam.

[0061] Furthermore, the second laser beam 9 is incident on the reflector 6 from top to bottom along a vertical direction, and the reflector 6 is located at the lower side of the first laser beam 5 .

[0062] Furthermore, the intersection of the incident light rays of the second laser beam 9 and the first laser beam 5 is located between the DMD chip 1 and the aperture Ⅰ2.

[0063] Furthermore, in the step S5, the reflector 6 is located between the DMD chip 1 and the aperture Ⅰ2.

[0064] Furthermore, in the step S6, the observation screen 8 is arranged in parallel with the aperture I2 and the aperture II3, and the observation screen 8 and the center points of the aperture I2 and the aperture II3 are located on the same straight line.

[0065] Furthermore, the observation screen 8 is located between the DMD chip 1 and the aperture Ⅰ2.

[0066] Furthermore, the observation screen 8 is located between the incident light of the second laser beam 9 and the aperture Ⅰ2.

[0067] Furthermore, in step S7, the five bright spots 10 located at the center of the chessboard image are determined according to the following method:

[0068] First, the geometric center point of the chessboard image formed on the observation screen 8 is determined, and then a central circle 11 is made with the geometric center point as the center, and the central circle 11 passes through four bright spots 10 that are closest to the geometric center point and are distributed in a cross shape. At the same time, there is a bright spot 10 at the center of the central circle 11, which together with the four bright spots 10 distributed in a cross shape on the central circle 11 constitute the five bright spots 10 located at the center of the chessboard image.

[0069] Furthermore, in step S7, when judging whether the position and direction of the reflector 6 are adjusted to the specified position and whether the chessboard image formed on the observation screen 8 meets the requirements, the morphology and changes of the bright spot 10 in the central area of ​​the chessboard image formed on the observation screen 8 can be obtained by observing the morphology and changes of the bright spot 10 in the central area of ​​the chessboard image formed on the observation screen 8. The specific method is:

[0070] When adjusting the position and direction of the reflector 6, the changes of the five bright spots 10 in the center of the chessboard image formed on the observation screen 8 can be observed at the same time. When the position and direction of the reflector 6 are not adjusted to the specified position, such as Figure 5 As shown, among the five bright spots 10 in the center of the chessboard image formed on the observation screen 8, there is a bright spot 10 with a brightness significantly higher than that of the other four bright spots 10, and its position is not at the center point of the chessboard image formed on the observation screen 8, that is, not at the center of the center circle 11; when the position and direction of the reflector 6 are adjusted to the specified position, as shown in FIG. Figure 4As shown, among the five bright spots 10 at the center of the chessboard image formed on the observation screen 8, the bright spot 10 with the highest brightness is located at the center point of the chessboard image formed on the observation screen 8, that is, at the center of the center circle 11, and the brightness of the bright spot 10 with the highest brightness is basically equal to or slightly higher than the brightness of the surrounding four bright spots 10. When observed with the naked eye, the five bright spots located at the center of the chessboard image have uniform brightness.

[0071] In addition, the present application also provides a device for detecting a micromirror deflection angle of a DMD, wherein the device detects the micromirror deflection angle of the DMD using the above-mentioned detection method.

[0072] Specifically, the DMD micromirror deflection angle detection device includes:

[0073] The detection object includes a DMD chip 1, an aperture I 2, an aperture II 3, a laser emitter 4, a reflector 6 and an observation screen 8. The laser emitter 4 can emit a first laser beam 5. The DMD chip 1 carries a checkerboard pattern 7 and introduces a second laser beam 9 at the same time. A number of bright spots 10 are formed in the checkerboard image formed on the observation screen 8 by the second laser beam 9 and the first laser beam 5. The deflection angle of the micromirror of the DMD is detected by the change of the bright spots 10.

[0074] In summary, the method and device for detecting the deflection angle of the micromirror of the DMD described in the present application have the advantages of simple structure, easy implementation, accurate detection of the deflection angle of the micromirror of the DMD, and simple operation process.

[0075] The embodiments of the present application are described above in conjunction with the accompanying drawings. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A method for detecting a micromirror deflection angle of a DMD, characterized in that: Includes steps: S1, place the DMD chip, aperture I, aperture II and laser emitter in sequence so that their center points are on the same straight line; S2, when the power of the DMD chip is disconnected, the position of the laser emitter is adjusted so that the first laser beam emitted by the laser emitter passes through the aperture II and the aperture I at the same time and hits the central area of ​​the DMD chip, and the fixed angle of the DMD is adjusted so that the light reflected by the DMD returns to the aperture I and the aperture II along the original path; S3, powering on the DMD chip and uploading a checkerboard pattern; S4, introducing a second laser beam so that it is incident in a direction perpendicular to the first laser beam; S5, introducing a reflector at one side of the first laser beam, adjusting the position and direction of the reflector so that the light spots formed on the reflector by the first laser beam and the second laser beam overlap, at which time the reflected light of the second laser beam will be incident on the DMD chip along a certain angle, and the incident angle of the reflected light of the second laser beam on the DMD chip is recorded as θ; S6, introducing an observation screen between the DMD chip and the aperture I, and observing a chessboard image formed on the observation screen; S7, fine-tuning the position and direction of the reflector so that the center of the chessboard image formed on the observation screen is five uniform bright spots; S8, measuring the incident angle θ of the reflected light of the second laser beam incident on the DMD chip at this time; S9, calculating the micromirror deflection angle θ0 of the DMD chip according to the incident angle θ measured in step S8, wherein θ0=0.5θ.

2. The method for detecting the micromirror deflection angle of a DMD according to claim 1, wherein: In step S1, the center points of the DMD chip, aperture I, aperture II and laser emitter are located on the same horizontal straight line.

3. The method for detecting the micromirror deflection angle of a DMD according to claim 1 or 2, characterized in that: The distance between the DMD chip and aperture I is recorded as h1, the distance between aperture I and aperture II is recorded as h2, and the distance between aperture II and the laser emitter is recorded as h3, then, h1<h3<h2.

4. The method for detecting the micromirror deflection angle of a DMD according to claim 1, wherein: The second laser beam is a green laser beam.

5. The method for detecting the micromirror deflection angle of a DMD according to claim 1 or 4, characterized in that: The second laser beam is incident on the reflector from top to bottom in a vertical direction, and the reflector is located at a lower side of the first laser beam.

6. The method for detecting the micromirror deflection angle of a DMD according to claim 1, characterized in that: The reflecting mirror is located between the DMD chip and the aperture Ⅰ.

7. The method for detecting the micromirror deflection angle of a DMD according to claim 1, characterized in that: The observation screen is arranged in parallel with the aperture I and the aperture II. The observation screen and the center points of the aperture I and the aperture II are located on the same straight line. The observation screen is located between the DMD chip and the aperture I.

8. The method for detecting the micromirror deflection angle of a DMD according to claim 1, wherein: In step S7, the five bright spots located at the center of the chessboard image are determined according to the following method: First, the geometric center point of the chessboard image formed on the observation screen is determined, and then a central circle is made with the geometric center point as the center. There is a bright spot at the center of the central circle, and the central circle passes through four bright spots that are closest to the geometric center point and are distributed in a cross shape, which together constitute the five bright spots located in the center of the chessboard image.

9. The method for detecting the micromirror deflection angle of a DMD according to claim 8, characterized in that: In step S7, when adjusting the position and direction of the reflector, the changes of the five bright spots in the center of the chessboard image formed on the observation screen are observed simultaneously. When the position and direction of the reflector are not adjusted to the specified position, among the five bright spots in the center of the chessboard image formed on the observation screen, the bright spot with the highest brightness is not located at the center of the center circle; when the position and direction of the reflector are adjusted to the specified position, the bright spot with the highest brightness is located at the center of the center circle.

10. A DMD micromirror deflection angle detection device, characterized in that: The detection device detects the deflection angle of the micromirror of the DMD using the detection method described in any one of claims 1 to 9.

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