CN108088365B - Digital micromirror camera coordinate accurate mapping method based on phase - Google Patents

Digital micromirror camera coordinate accurate mapping method based on phase Download PDF

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CN108088365B
CN108088365B CN201711370888.8A CN201711370888A CN108088365B CN 108088365 B CN108088365 B CN 108088365B CN 201711370888 A CN201711370888 A CN 201711370888A CN 108088365 B CN108088365 B CN 108088365B
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digital micromirror
dmd
ccd
charge coupled
coupled device
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CN108088365A (en
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于连栋
罗辉
夏豪杰
李维诗
邓华夏
张进
张炜
赵会宁
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Hefei University of Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/002—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates

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Abstract

The invention discloses a phase-based accurate coordinate mapping method for a digital micromirror camera, wherein the digital micromirror camera comprises a Digital Micromirror Device (DMD), a Charge Coupled Device (CCD), a first lens group and a second lens group; mapping matching first controlsThe digital micromirror device DMD generates transverse sine stripes and longitudinal sine stripes, and then calculates the transverse phase distribution of the digital micromirror device DMD
Figure DDA0001513716830000011
Longitudinal phase distribution
Figure DDA0001513716830000012
Finally, determining pixel coordinates (i, j) of charge coupled device CCD and DMD mirror element coordinates (v) of digital micromirror deviced(i，j)，ud(i, j)). The digital micromirror device DMD and the charge coupled device CCD do not need to be adjusted and aligned in space, so that a complex adjusting process is avoided, and the whole process of establishing a mapping relation is simpler and more convenient; the mapping relation is established by adopting a phase calculation mode, the corresponding DMD mirror element coordinate of the digital micromirror device can be directly calculated for all CCD pixel coordinates of the charge coupled device, and the mapping relation is more accurate.

Description

Digital micromirror camera coordinate accurate mapping method based on phase
Technical Field
The invention relates to the field of high-dynamic camera application, in particular to a digital micromirror camera coordinate accurate mapping method based on phase.
Background
The digital micromirror camera mainly comprises a digital micromirror device DMD and a CCD camera. The DMD is a spatial optical modulator that can precisely attenuate light energy reaching an image plane at a pixel level. After attenuation adjustment, bright objects and dark objects in the observation scene can be imaged in the CCD camera at the same time. Compared with a common CCD camera or a CMOS camera, the digital micromirror camera has a higher dynamic range, can meet the observation requirement of a scene with a high dynamic range, and has wide application in a plurality of fields such as high dynamic imaging, spectral analysis, scanning measurement and the like.
In order to realize the pixel-level brightness adjustment function of the digital micromirror camera, the key is to establish the precise mapping matching relationship between the DMD mirror element and the CCD pixel of the charge coupled device. In a conventional method for establishing a mapping relationship, pixels of a DMD (digital micromirror device) and pixels of a CCD (charge coupled device) need to be spatially aligned by manual adjustment. Then setting a digital micromirror device DMD to make the plane present a checkerboard pattern, imaging the checkerboard pattern by a charge coupled device CCD, and establishing a mapping relation between the DMD mirror element coordinates and the CCD pixel coordinates of the charge coupled device at the corner position by adopting a corner detection method.
It can be seen that the conventional method for establishing mapping relationship has the following disadvantages: 1) the DMD mirror element and the CCD pixel of the charge coupled device of the digital micromirror device need to be adjusted and aligned in space, the adjusting process is complicated, and the operation is difficult; 2) the method can only establish the mapping relation between DMD mirror elements and CCD pixels of the charge coupled device at the corner positions, and only can establish the mapping relation between a small number of DMD mirror elements and CCD pixels due to a certain distance between the corners in the checkerboard pattern, and the mapping relation of the rest positions needs to be determined by a fitting method and is not accurate enough.
Disclosure of Invention
The invention aims to provide a phase-based accurate coordinate mapping method for a digital micromirror camera, which can conveniently, quickly and accurately establish the mapping relation between DMD mirror elements and CCD pixels of a charge coupled device of a digital micromirror device.
In order to achieve the purpose, the technical scheme of the invention is as follows: a digital micromirror camera coordinate accurate mapping method based on phase comprises a digital micromirror camera capable of carrying out pixel-level adjustment on image continuous reading, wherein the digital micromirror camera comprises a Digital Micromirror Device (DMD), a charge-coupled device (CCD), a first lens group and a second lens group; the first lens group is a fixed-magnification imaging objective lens and images the surface of the object to be measured on the digital micromirror device DMD completely; the digital micromirror device DMD consists of a plurality of mirror elements which are independently addressed and controlled, and accurately modulates the light intensity of incident light; the second lens group is a zoom lens and completely images an image on the digital micromirror device DMD on the charge coupled device CCD; the optical axes of the digital micromirror device DMD, the second lens group and the charge coupled device CCD are superposed;
establishing a corresponding relation between the DMD mirror element coordinates and the CCD pixel coordinates of the charge coupled device for mapping and matching, and specifically comprising the following steps of:
controlling a Digital Micromirror Device (DMD) to sequentially generate a group of transverse sine stripes and a group of longitudinal sine stripes, and simultaneously acquiring transverse stripe images and longitudinal stripe images by a Charge Coupled Device (CCD);
step two, calculating the transverse phase distribution of the digital micromirror device DMD
Figure GDA0002249222380000025
Longitudinal phase distribution
Figure GDA0002249222380000026
DMD lateral phase distribution of digital micromirror device
Figure GDA0002249222380000027
The longitudinal phase distribution of the DMD is calculated by the following formula (1)
Figure GDA0002249222380000028
Calculated by the following formula (2):
Figure GDA0002249222380000021
Figure GDA0002249222380000022
in the above formulas (1) and (2), N is the total phase shift step number, IHn(i, j) is the brightness distribution of the transverse stripe during the phase shift of the nth step, and is obtained by measuring the image of the transverse stripe collected by the charge coupled device CCD; i isVn(i, j) is the brightness distribution of the longitudinal stripe during the phase shift of the nth step, which is obtained by measuring the image of the longitudinal stripe collected by the charge coupled device CCD; (i, j) are pixel coordinates of the charge coupled device CCD;
step three, determining pixel coordinates (i, j) of the charge coupled device CCD and mirror element coordinates (v) of the digital micromirror device DMDd(i,j),ud(i, j)), where vd(i, j) is determined by the following formula (3) ud(i, j) is determined by the following formula (4):
Figure GDA0002249222380000023
Figure GDA0002249222380000024
in the above formulae (3) and (4), THIs the period width, T, of the transverse sinusoidal stripeVIs the period width of the longitudinal sinusoidal stripes.
The invention has the beneficial effects that:
1) when the mapping relation between the DMD mirror element and the CCD pixel of the charge coupled device is established, the DMD mirror element and the CCD pixel of the charge coupled device do not need to be adjusted and aligned in space, so that a complicated adjusting process is avoided, and the whole process of establishing the mapping relation is simpler and more convenient;
2) the invention adopts a phase calculation mode to establish the mapping relation between the DMD mirror elements and the CCD pixels of the charge coupled device, and can directly calculate the corresponding DMD mirror element coordinates of the digital micromirror device for all the CCD pixel coordinates of the charge coupled device. The mapping relation established by the invention is more accurate because the calculation processes of fitting, interpolation and the like are saved.
Drawings
FIG. 1 is a schematic diagram of a digital micromirror camera;
FIG. 2 is a horizontal stripe pattern generated by the DMD;
FIG. 3 is a longitudinal stripe pattern generated by the DMD;
FIG. 4 is a transverse phase profile;
FIG. 5 is a longitudinal phase profile;
fig. 6 is a schematic diagram of a DMD mirror element and a CCD pixel mapping of the DMD.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.
A phase-based accurate coordinate mapping method for a digital micromirror camera comprises a digital micromirror camera capable of performing pixel-level adjustment on continuous reading of images, as shown in FIG. 1, the digital micromirror camera comprises a digital micromirror device DMD1, a charge-coupled device CCD4, a first lens group 2, and a second lens group 3; the first lens group 2 is a fixed-magnification imaging objective lens and images the surface of the object to be measured on the digital micromirror device DMD1 completely; the digital micromirror device DMD1 is composed of a plurality of mirror elements which are independently addressed and controlled, and is used for accurately modulating the light intensity of incident light; the second lens group 3 is a zoom lens and completely images an image on the digital micromirror device DMD1 on the CCD 4; the optical axes of the digital micromirror device DMD1, the second lens group 3 and the charge coupled device CCD4 are coincident.
Establishing a corresponding relation between the coordinates of the DMD1 mirror elements of the digital micromirror device and the coordinates of the pixels of the CCD4, and performing mapping matching, wherein the method specifically comprises the following steps:
step one, as shown in fig. 2 and 3, controlling a digital micromirror device DMD1 to sequentially generate a group of transverse sinusoidal stripes and a group of longitudinal sinusoidal stripes, and simultaneously collecting transverse stripe images and longitudinal stripe images by a charge coupled device CCD 4;
step two, calculating the transverse phase distribution of the digital micromirror device DMD1 shown in FIG. 4 and FIG. 5
Figure GDA0002249222380000035
Longitudinal phase distribution
Figure GDA0002249222380000036
Digital micromirror device DMD1 transverse phase distribution
Figure GDA0002249222380000037
The longitudinal phase distribution of the DMD1 of the digital micromirror device is calculated by the following equation (1)
Figure GDA0002249222380000038
Calculated by the following formula (2):
Figure GDA0002249222380000031
Figure GDA0002249222380000032
in the above formulas (1) and (2), N is the total phase shift step number, IHn(i, j) is the luminance distribution of the lateral stripe at the phase shift of the nth step, which is obtained by measuring the image of the lateral stripe collected by the CCD 4; i isVn(i, j) is the brightness distribution of the longitudinal stripe at the phase shift of the nth step, which is obtained by measuring the image of the longitudinal stripe collected by the CCD 4; (i, j) are pixel coordinates of the charge coupled device CCD;
step three, determining pixel coordinates (i, j) of the charge coupled device CCD and mirror element coordinates (v) of the digital micromirror device DMDd(i,j),ud(i, i)) as shown in FIG. 6, where vd(i, j) is determined by the following formula (3) ud(i, j) is determined by the following formula (4):
Figure GDA0002249222380000033
Figure GDA0002249222380000034
in the above formulae (3) and (4), THIs the period width, T, of the transverse sinusoidal stripeVIs the period width of the longitudinal sinusoidal stripes.
The described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Claims (1)

1. A digital micromirror camera coordinate accurate mapping method based on phase is characterized by comprising a digital micromirror camera capable of carrying out pixel-level adjustment on continuous reading of an image, wherein the digital micromirror camera comprises a Digital Micromirror Device (DMD), a charge-coupled device (CCD), a first lens group and a second lens group; the first lens group is a fixed-magnification imaging objective lens and images the surface of the object to be measured on the digital micromirror device DMD completely; the digital micromirror device DMD consists of a plurality of mirror elements which are independently addressed and controlled, and accurately modulates the light intensity of incident light; the second lens group is a zoom lens and completely images an image on the digital micromirror device DMD on the charge coupled device CCD; the optical axes of the digital micromirror device DMD, the second lens group and the charge coupled device CCD are superposed;
establishing a corresponding relation between the DMD mirror element coordinates and the CCD pixel coordinates of the charge coupled device for mapping and matching, and specifically comprising the following steps of:
controlling a Digital Micromirror Device (DMD) to sequentially generate a group of transverse sine stripes and a group of longitudinal sine stripes, and simultaneously acquiring transverse stripe images and longitudinal stripe images by a Charge Coupled Device (CCD);
step two, calculating the transverse phase distribution of the digital micromirror device DMD
Figure 606137DEST_PATH_IMAGE001
Longitudinal phase distribution
Figure 116752DEST_PATH_IMAGE002
DMD lateral phase distribution of digital micromirror device
Figure 365331DEST_PATH_IMAGE001
The longitudinal phase distribution of the DMD is calculated by the following formula (1)
Figure 88436DEST_PATH_IMAGE002
Calculated by the following formula (2):
Figure 637229DEST_PATH_IMAGE003
（1）
Figure 787588DEST_PATH_IMAGE004
（2）
in the above formulas (1) and (2), N is the total phase shift step number,
Figure 789042DEST_PATH_IMAGE005
the luminance distribution of the transverse stripe during the phase shift of the nth step is obtained by measuring the image of the transverse stripe acquired by the charge coupled device CCD;
Figure 473095DEST_PATH_IMAGE006
the brightness distribution of the longitudinal stripe during the phase shift of the nth step is obtained by measuring the image of the longitudinal stripe acquired by the charge coupled device CCD;
Figure 702826DEST_PATH_IMAGE007
is the pixel coordinate of the charge coupled device CCD;
step three, determining the pixel coordinates of the charge coupled device CCD
Figure 24086DEST_PATH_IMAGE007
And DMD mirror element coordinate of digital micromirror device
Figure 371891DEST_PATH_IMAGE008
A mapping relationship between, wherein
Figure 577744DEST_PATH_IMAGE009
Determined by the following formula (3),
Figure 694605DEST_PATH_IMAGE010
determined by the following formula (4):
Figure 593291DEST_PATH_IMAGE011
（3）
Figure 929856DEST_PATH_IMAGE012
（4）
in the above formulas (3) and (4),
Figure 673821DEST_PATH_IMAGE013
is the period width of the transverse sinusoidal stripes,
Figure 910768DEST_PATH_IMAGE014
is the period width of the longitudinal sinusoidal stripes.
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