CN116754189A - Method and device for detecting deflection angle of micromirror of DMD - Google Patents

Abstract

The application provides a method and a device for detecting a deflection angle of a micromirror of a DMD, comprising the following steps: s1, a DMD chip, a diaphragm I, a diaphragm II and a laser emitter are sequentially arranged; s2, the power supply of the DMD chip is disconnected, a laser transmitter transmits a first laser beam to pass through a diaphragm II and a diaphragm I to be beaten in the central area of the DMD chip, and a light source reflected by the DMD returns to the diaphragm I and the diaphragm II; s3, electrifying the DMD chip and uploading the checkerboard pattern; s4, introducing a second laser beam; s5, introducing a reflector to enable light spots formed on the reflector by the first laser beam and the second laser beam to coincide, and recording an incident angle of the second laser beam on the DMD chip as theta; s6, introducing an observation screen; s7, finely adjusting a reflector to enable the center of the chessboard pattern image on the observation screen to be five uniform bright spots; s8, measuring an incident angle theta; s9, calculating the deflection angle theta of the micromirror of the DMD chip ₀ ，θ ₀ The method and the device for detecting the deflection angle of the micromirror of the DMD have the advantages of accurate detection of the deflection angle of the micromirror of the DMD and simple operation process.

Description

A DMD micromirror deflection angle detection method and device

Technical field

The invention belongs to the field of optical technology, and specifically relates to a DMD micromirror deflection angle detection method and device.

Background technique

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 has increased dramatically. 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 volume storage technology, holographic storage technology has ultra-high theoretical storage density and ultra-fast data conversion rate, and is considered a strong competitor of the new generation of storage technology.

At present, the amplitude-type holographic storage system is one of the holographic storage systems that people are mainly studying, because the CCD detector can directly detect the intensity information, and the amplitude-type spatial light modulator, such as DMD (digital micromirror device) can provide very high Refresh rate, which increases the rate at which data is transferred.

Among them, the Digital Micromirror Device (DMD) is a micro-optical 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. On the microchip, each micro-mirror can independently flip between the two states of plus and minus 12 degrees around its axis, thereby modulating the amplitude of the light field. Each optical switch has a reflector connected to a memory cell. By controlling the charge state of the memory unit and changing the rotational motion and domain response of the micro-mirror around a fixed axis, the modulation of the angle direction and stagnation time of the light incident through each unit is achieved. DMD can realize the spatial modulation and gating of light. The time required for gating is on the microsecond level, and there is no mechanical movement of the device during the modulation process. However, DMD can only realize beam modulation on a two-dimensional plane in space and cannot realize the spatial propagation angle. encoding and modulation.

In the laser direct imaging system, the long side direction of the DMD mounting surface and the step direction of exposure theoretically need to maintain an ideal working angle θ, so that there is no up and down 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. To calculate the size of the error, it is necessary to calculate the actual assembly angle of the DMD. The assembly angle θ', that is, the deflection angle of the micromirror, is measured, and then combined with the ideal working angle θ to obtain the working angle error e.

Currently, Texas Instruments (TI), a well-known DMD manufacturer in the world, has an angle error range of ±1° when producing DMDs. Although this can meet most basic applications of DMD, it cannot be used in some application fields with high precision requirements, such as Fields such as holographic storage, maskless lithography, and super-resolution microscopy have relatively high requirements on the angular error of DMD. In order to accurately measure the angular error of DMD, it is necessary to provide a more accurate method for detecting the micromirror deflection angle of DMD.

At present, although some DMD micromirror deflection angle detection systems have appeared on 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 that is simple in structure, easy to implement, accurate in detecting the DMD micromirror deflection angle, and has a simple operation process is one of the technical problems that those skilled in the art urgently need to solve.

Contents of the invention

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 view of the above existing technical problems, so as to achieve accurate and convenient detection of the deflection angle of the micromirror of the DMD.

In view of this, the present invention provides a DMD micromirror deflection angle detection method, which includes the steps:

S1, place the DMD chip, aperture I, aperture II and laser transmitter in order so that their center points are on the same straight line;

S2, when the power supply of the DMD chip is turned off, adjust the position of the laser emitter so that the first laser beam it emits passes through the aperture II and the aperture I at the same time and hits the center of the DMD chip. area, adjust the fixed angle of the DMD so that the light reflected by the DMD returns to the aperture I and aperture II;

S3, energize the DMD chip and upload the checkerboard pattern;

S4, introduce the second laser beam so that it is incident in a direction perpendicular to the first laser beam;

S5, introduce a reflecting mirror on one side of the first laser beam, and adjust the position and direction of the reflecting mirror so that the light spots formed by the first laser beam and the second laser beam on the reflecting mirror coincide with each other, At this time, the reflection line of the second laser beam will be incident on the DMD chip at a certain angle, and the incident angle at which the reflection line of the second laser beam is incident on the DMD chip is recorded as θ;

S6, introduce an observation screen between the DMD chip and the aperture I, and observe the checkerboard image formed on the observation screen;

S7, fine-tune the position and direction of the reflector so that the center of the checkerboard image formed on the observation screen is five uniform bright spots;

S8, measure the incident angle θ at which the reflection line of the second laser beam is incident on the DMD chip at this time;

S9: Calculate the micromirror deflection angle θ ₀ of the DMD chip based on the incident angle θ measured in step S8, where θ ₀ =0.5θ.

Further, 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.

Further, the distance between the DMD chip and the aperture I is recorded as h1, the distance between the aperture I and the aperture II is recorded as h2, and the distance between the aperture II and the laser emitter is Recorded as h3, then, h1＜h3＜h2.

Further, the second laser beam is a green laser beam.

Further, the second laser beam is incident on the reflecting mirror from top to bottom in the vertical direction, and the reflecting mirror is located on the lower side of the first laser beam.

Further, the reflecting mirror is located between the DMD chip and the aperture I.

Further, the observation screen is arranged parallel to the aperture I and the aperture II, the observation screen is located on the same straight line as the center points of the aperture I and the aperture II, and the observation screen is located between the DMD chip and the light between gate Ⅰ.

Further, in step S7, the five bright spots located in the center of the checkerboard image are determined according to the following method:

First, determine the geometric center point of the checkerboard image formed on the observation screen, and then use the geometric center point as the center to make a central circle. There is a bright spot at the center of the central circle, and the central circle passes through a distance of The four bright spots closest to the geometric center point and distributed in a cross shape together constitute the five bright spots located in the center of the checkerboard image.

Further, in step S7, when adjusting the position and direction of the reflector, simultaneously observe changes in the five bright spots in the center of the checkerboard image formed on the observation screen. When the position and direction of the reflector are When the direction is not adjusted to the designated position, among the five bright spots in the center of the checkerboard image formed on the observation screen, the position of the brightest spot with the highest brightness is not at the center of the central circle; when the position of the reflector When the and direction are adjusted to the specified position, the brightest spot with the brightest brightness is located at the center of the central circle.

A micromirror deflection angle detection device of DMD, which detects the micromirror deflection angle of DMD using the above detection method.

The DMD micromirror deflection angle detection method and device of the present invention have the advantages of simple structure, easy implementation, accurate detection of the DMD micromirror deflection angle, and simple operation process.

Description of the drawings

Figure 1 is a schematic diagram of the arrangement of the DMD chip, aperture I, aperture II and laser emitter according to the present invention;

Figure 2 is a schematic diagram of the arrangement of the observation screen and reflector according to the present invention;

Figure 3 is a schematic diagram of the checkerboard pattern according to the present invention;

Figure 4 is an example of a checkerboard image formed on the observation screen of the present invention;

Figure 5 is another example of a checkerboard image formed on the observation screen of the present invention.

The marks in the figure are expressed as:

1. DMD chip; 2. Aperture I; 3. Aperture II; 4. Laser transmitter; 5. First laser beam; 6. Reflector; 7. Checkerboard pattern; 8. Observation screen; 9. Second Laser beam; 10, bright spot; 11, center circle.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art fall within the scope of protection of this application.

In the description of the present application, it should be noted that the terms used here are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. For convenience of description, the dimensions of various parts shown in the drawings are not drawn according to actual proportional relationships. Techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods and devices should be considered part of the authorized specification. In all examples shown and discussed herein, any specific values are to be construed as illustrative only and not as limiting. Accordingly, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters refer to similar items in the following figures, so that once an item is defined in one figure, it does not need further discussion in subsequent figures.

It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects and are not used to describe a specific order or sequence. It is to be understood that the figures so used are interchangeable under appropriate circumstances so that the embodiments of the present application can be practiced in orders other than those illustrated or described herein, and that "first," "second," etc. are distinguished Objects are usually of one type, and the number of objects is not limited. For example, the first object can be one or multiple. In addition, "and/or" in the description and claims indicates at least one of the connected objects, and the character "/" generally indicates that the related objects are in an "or" relationship.

It should be noted that in the description of this application, terms such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" indicate The orientation or positional relationship is generally based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description. Without explanation to the contrary, these positional words do not indicate or imply the device or device referred to. Components must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be construed as limiting the scope of the present application; the orientation words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

It should be noted that in this application, the terms "comprising", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device that includes a series of elements not only includes those elements , but also includes other elements not expressly listed or inherent in such process, method, article or apparatus. Without further limitation, an element defined by the statement "comprises a..." does not exclude the presence of additional identical elements in a process, method, article or apparatus that includes that element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, but may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved. Functions may be performed, for example, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

As shown in Figures 1 to 4, a DMD micromirror deflection angle detection method includes the steps:

S1, place the DMD chip 1, aperture I2, aperture II3 and laser transmitter 4 in order so that their center points are on the same straight line;

S2, when the power supply of the DMD chip 1 is turned off, adjust the position of the laser transmitter 4 so that the first laser beam 5 it emits passes through the aperture II 3 and the aperture I2 at the same time, hitting the target. Describe the central area of the DMD chip 1, adjust the fixed angle of the DMD, and allow the light reflected by the DMD to return to the aperture I and the aperture II;

S3, power on the DMD chip 1 and upload the checkerboard pattern 7;

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

S5, introduce a reflector 6 on one side of the first laser beam 5 and adjust the position and direction of the reflector 6 so that the first laser beam 5 and the second laser beam 9 are formed on the reflector 6 The light spots on the DMD chip 1 are basically coincident. At this time, the reflection line of the second laser beam 9 will be incident on the DMD chip 1 along a certain angle. The incident angle on chip 1 is recorded as θ;

S6, introduce the observation screen 8 between the DMD chip 1 and the aperture I2, and observe the checkerboard image formed on the observation screen 8;

S7, fine-tune the position and direction of the reflector 6 so that the center of the checkerboard image formed on the observation screen 8 is five uniform bright spots 10;

S8, measure the incident angle θ at which the reflection line of the second laser beam 9 is incident on the DMD chip 1 at this time;

S9: Calculate the micromirror deflection angle θ ₀ of the DMD chip 1 based on the incident angle θ measured in step S8, where θ ₀ =0.5θ.

Further, the DMD chip 1, aperture I2 and aperture II3 are arranged in parallel.

Preferably, in step S1, the DMD chip 1, aperture I2, aperture II3 and laser emitter 4 can be placed in sequence so that their center points are located on the same horizontal straight line.

Further, let the distance between the DMD chip 1 and the aperture I2 be h1, the distance between the aperture I2 and the aperture II3 be h2, and the distance between the aperture II3 and the laser emitter 4 The distance is recorded as h3, then, h1＜h3＜h2.

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

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

Further, in step S2, the wavelength of the first laser beam 5 emitted by the laser transmitter 4 is 680-740 nm.

Further, in step S3, the checkerboard pattern 7 is a checkerboard pattern composed of black and white squares.

Further, in step S3, uploading the checkerboard pattern 7 means marking the checkerboard pattern 7 on the Fourier plane.

Further, in step S4, the second laser beam 9 is a green laser beam.

Further, the second laser beam 9 is incident on the reflecting mirror 6 from top to bottom in the vertical direction, and the reflecting mirror 6 is located on the lower side of the first laser beam 5 .

Furthermore, the intersection point 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.

Further, in step S5, the reflector 6 is located between the DMD chip 1 and the aperture I2.

Further, in the step S6, the observation screen 8 is arranged parallel to the aperture I2 and the aperture II3, and the center points of the observation screen 8 and the aperture I2 and the aperture II3 are located on the same straight line.

Further, the observation screen 8 is located between the DMD chip 1 and the aperture I2.

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

Further, in step S7, the five bright spots 10 located in the center of the checkerboard image are determined according to the following method:

First, determine the geometric center point of the checkerboard image formed on the observation screen 8, and then use the geometric center point as the center to make a central circle 11. The central circle 11 passes through the nearest geometric center point and is distributed in a cross shape. The four bright spots are 10. 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 center of the checkerboard image. 10 of the five bright spots.

Further, in step S7, when determining whether the position and direction of the reflector 6 are adjusted to a designated position, and whether the checkerboard image formed on the observation screen 8 meets the requirements, it can be determined by observing the observation screen. The morphology and changes of the bright spot 10 in the center area of the checkerboard image formed on 8 are obtained. The specific method is:

When adjusting the position and direction of the reflector 6, changes in the five bright spots 10 in the center of the checkerboard image formed on the observation screen 8 can be observed simultaneously. When the position and direction of the reflector 6 are not adjusted to When specifying the position, as shown in Figure 5, among the five bright spots 10 in the center of the checkerboard image formed on the observation screen 8, there will be a bright spot with a brightness significantly higher than that of the four bright spots 10 with the highest brightness. 10, and its position is not at the center point of the checkerboard image formed on the observation screen 8, that is, it is not at the center of the central circle 11; when the position and direction of the reflector 6 are adjusted to the designated position , as shown in Figure 4, among the five bright spots 10 in the center of the checkerboard image formed on the observation screen 8, the brightest spot 10 with the highest brightness is located at the center point of the checkerboard image formed on the observation screen 8 , that is, it is located at the center of the central 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 four surrounding bright spots 10. When observed with the naked eye, the five spots located in the center of the checkerboard image Each bright spot has uniform brightness.

In addition, this application also provides a DMD micromirror deflection angle detection device, which uses the above detection method to detect the DMD micromirror deflection angle.

Specifically, the micromirror deflection angle detection device of the DMD includes:

Detection object DMD chip 1, aperture I2, aperture II3, laser transmitter 4, reflector 6 and observation screen 8, the laser transmitter 4 can emit the first laser beam 5, the DMD chip 1 uploads a checkerboard pattern 7. At the same time, the second laser beam 9 is introduced, and several bright spots 10 are formed in the checkerboard image formed on the observation screen 8 through the second laser beam 9 and the first laser beam 5. Changes in the micromirror deflection angle of the DMD are detected.

In summary, the DMD micromirror deflection angle detection method and device described in this application have the advantages of simple structure, easy implementation, accurate detection of the DMD micromirror deflection angle, and simple operation process.

The embodiments of the present application are described above in conjunction with the accompanying drawings. The embodiments and features in the embodiments can be combined with each other without conflict. The present application is not limited to the above-mentioned specific implementations. The above-mentioned specific embodiments are only illustrative and not restrictive. Under the inspiration of this application, those of ordinary skill in the art can also make other modifications without departing from the purpose of this application and the scope protected by the claims. Many forms fall within the protection of this application.

Claims (10)

1. A DMD micromirror deflection angle detection method, characterized by comprising the steps: S1, place the DMD chip, aperture I, aperture II and laser transmitter in order so that their center points are on the same straight line; S2, when the power supply of the DMD chip is turned off, adjust the position of the laser emitter so that the first laser beam it emits passes through the aperture II and the aperture I at the same time and hits the center of the DMD chip. area, adjust the fixed angle of the DMD so that the light reflected by the DMD returns to the aperture I and aperture II; S3, energize the DMD chip and upload the checkerboard pattern; S4, introduce the second laser beam so that it is incident in a direction perpendicular to the first laser beam; S5, introduce a reflecting mirror on one side of the first laser beam, and adjust the position and direction of the reflecting mirror so that the light spots formed by the first laser beam and the second laser beam on the reflecting mirror coincide with each other, At this time, the reflection line of the second laser beam will be incident on the DMD chip at a certain angle, and the incident angle at which the reflection line of the second laser beam is incident on the DMD chip is recorded as θ; S6, introduce an observation screen between the DMD chip and the aperture I, and observe the checkerboard image formed on the observation screen; S7, fine-tune the position and direction of the reflector so that the center of the checkerboard image formed on the observation screen is five uniform bright spots; S8, measure the incident angle θ at which the reflection line of the second laser beam is incident on the DMD chip at this time; S9: Calculate the micromirror deflection angle θ ₀ of the DMD chip based on the incident angle θ measured in step S8, where θ ₀ =0.5θ. 2. The micromirror deflection angle detection method of DMD according to claim 1, characterized in that, in the step S1, the center points of the DMD chip, aperture I, aperture II and laser emitter are located at the same On a straight horizontal line. 3. The micromirror deflection angle detection method of DMD according to claim 1 or 2, characterized in that the distance between the DMD chip and the aperture I is recorded as h1, and the distance between the aperture I and the aperture II is h1. The distance between is h2, and the distance between the aperture II and the laser emitter is h3, then, h1＜h3＜h2. 4. The DMD micromirror deflection angle detection method according to claim 1, wherein the second laser beam is a green laser beam. 5. The micromirror deflection angle detection method of DMD according to claim 1 or 4, characterized in that the second laser beam is incident on the reflecting mirror from top to bottom along the vertical direction, and the reflection A mirror is located on the underside of the first laser beam. 6. The DMD micromirror deflection angle detection method according to claim 1, characterized in that the reflecting mirror is located between the DMD chip and the aperture I. 7. The micromirror deflection angle detection method of DMD according to claim 1, characterized in that the observation screen is arranged parallel to the aperture I and the aperture II, and the observation screen is arranged parallel to the aperture I and the aperture II. The center point of II is located on the same straight line, and the observation screen is located between the DMD chip and aperture I. 8. The micromirror deflection angle detection method of DMD according to claim 1, characterized in that, in the step S7, the five bright spots located in the center of the checkerboard image are determined according to the following method: First, determine the geometric center point of the checkerboard image formed on the observation screen, and then use the geometric center point as the center to make a central circle. There is a bright spot at the center of the central circle, and the central circle passes through a distance of The four bright spots closest to the geometric center point and distributed in a cross shape together constitute the five bright spots located in the center of the checkerboard image. 9. The micromirror deflection angle detection method of DMD according to claim 8, characterized in that, in the step S7, when adjusting the position and direction of the reflector, the chessboard formed on the observation screen is simultaneously observed. Changes in the five bright spots in the center of the checkerboard image. 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 checkerboard image formed on the observation screen, the brightest spot is the brightest spot. The spot position is not at the center of the central circle; when the position and direction of the reflector are adjusted to the designated position, the brightest spot with the brightest brightness is at the center of the central circle. 10. A micromirror deflection angle detection device of a DMD, characterized in that the detection device uses the detection method described in any one of claims 1 to 9 to detect the micromirror deflection angle of the DMD.