CN113099145A - Imaging device and design method thereof - Google Patents

Abstract

The invention relates to an imaging device, which comprises an optical compensation system module, an acquisition circuit module capable of acquiring images and a computer capable of processing the images. The acquisition circuit module comprises an image acquisition circuit board provided with a CMOS image sensor. The light emitted by the optical compensation system module is emitted to the acquisition circuit module, and the acquisition circuit module is connected to the computer. According to the invention, a set of imaging device is built, the collection of image photoelectric signals can be completed, the image information can not be lost, and the imaging function with higher resolution is realized.

Description

Imaging device and design method thereof

Technical Field

The invention relates to the technical field of imaging, in particular to an imaging device and a design method of the imaging device.

Background

A CMOS image sensor is a kind of solid-state imaging sensor. The CMOS image sensor generally comprises an image sensor cell array, a row driver, a column driver, a timing control logic, an AD converter, a data bus output interface, a control interface, etc., which are usually integrated on the same silicon chip. The working process can be generally divided into a reset part, a photoelectric conversion part, an integration part and a reading part. The direct use of CMOS image sensors to capture image information may result in loss of image information or the capture of no image information.

Disclosure of Invention

In order to solve the problem that image information is lost or no image information can be acquired when the CMOS image sensor is directly used for acquiring the image information, the invention provides a circuit acquisition board and an optical system formed by combining optical devices such as a lens, an aperture and the like to be matched with the CMOS image sensor to finish the acquisition of image photoelectric signals.

The invention firstly provides an imaging device which comprises an optical compensation system module, an acquisition circuit module capable of acquiring images and a computer capable of processing the images. The acquisition circuit module comprises an image acquisition circuit board provided with a CMOS image sensor. The light emitted by the optical compensation system module is emitted to the acquisition circuit module, and the acquisition circuit module is connected to the computer.

As a further improvement of the imaging device of the present invention, the optical compensation system module includes a light source, a color chart, a concave lens, a convex lens, a diaphragm, a filter and an empty lens barrel; the light source emits light to the color comparison card, and the light is reflected by the color comparison card and then sequentially passes through the concave lens, the convex lens, the diaphragm, the filter and the hollow lens cone.

As a further improvement of the imaging device of the present invention, the CMOS image sensor is of a model MT9M 001; light passing through the hollow lens barrel is emitted to the CMOS image sensor; the image acquisition circuit board is connected with the computer by using a USB data line.

As a further improvement of the imaging apparatus of the present invention, the optical compensation system module further includes a dark box; the light source, the colorimetric card, the concave lens, the convex lens, the diaphragm, the filter, the hollow lens barrel and the image acquisition circuit board are all arranged in the dark box; the computer is mounted outside the dark box.

The invention further provides a design method of the imaging device. The design method comprises the design of an acquisition circuit module and the design of an optical compensation system module. The design of the acquisition circuit module comprises the step of designing image acquisition software by using a principle of extracting library functions and utilizing microsoft visual basic c + + software, wherein the image acquisition software is installed in the acquisition circuit module.

As a further improvement of the design method of the imaging device of the present invention, the optical compensation system module is designed by adopting ZEMAX optical design software to design the optical path, including inputting the curvature radius, the optical wavelength and the field of view parameters of the lens in the ZEMAX optical design software to obtain an optical structure model, then optimizing the optical structure model to obtain the designed optimized system parameters, and designing the optical path according to the optimized system parameters.

As a further improvement of the design method of the imaging apparatus of the present invention, the design method further includes designing an image processing software module using microsoft visual c + + software using the principle of extracting library functions, the image processing software module being installed in the computer, the image processing software module being capable of performing sharpening processing on an image.

As a further improvement of the design method of the imaging device of the present invention, the computer is further installed with an iseetest software; the design method further comprises evaluating the imaging device using iseetest software; the evaluation comprises single resolution evaluation and comparison evaluation. The single-item resolution evaluation takes the pixel and the resolution of single imaging of the imaging device before or after image processing as evaluation objects. The contrast evaluation takes the pixels imaged by the imaging device twice before and after image processing and resolution contrast as evaluation objects.

As a further improvement of the design method of the imaging apparatus of the present invention, the evaluation takes a standard resolution test card as an image acquisition subject; and during evaluation, one block of the central area of the standard resolution test card is intercepted to be used as an evaluation sample, and the shot image of the standard resolution test card is analyzed to judge the pixel and the resolution of the imaging device.

As a further improvement of the design method of the imaging device of the present invention, the design method further includes a step of debugging and detecting the imaging device according to the evaluation result after evaluating the imaging device.

The invention has the beneficial effects that: through setting up optical compensation system module, the collection circuit module that can gather the image and the computer system that can handle the image, install CMOS image sensor on the collection circuit module, set up one set of imaging device, can accomplish the collection of image photoelectricity signal, and image information can not lose, realizes the imaging function of higher resolution.

Drawings

Fig. 1 is a schematic view of the overall structure of an image forming apparatus of an embodiment of the present invention.

Fig. 2 is a block diagram of the structural design of the image acquisition circuit board in fig. 1.

Fig. 3 is a schematic design diagram of the image acquisition circuit board in fig. 1.

Figure 4 is a ZEMAX optical system parameters and two-dimensional plot of an embodiment of the present invention.

FIG. 5 is an interface for evaluating a function and setting a wavelength of an optical system according to an embodiment of the present invention.

FIG. 6 shows the optimized system data of the optical model according to the embodiment of the present invention.

FIG. 7 is a graph of MTF function before optimization according to an embodiment of the present invention.

FIG. 8 is a graph of an optimized MTF function according to an embodiment of the present invention.

Fig. 9 is a dot-column diagram of a ZEMAX system page of an embodiment of the present invention.

FIG. 10 is an image distance diagram of an optical system according to an embodiment of the present invention.

Fig. 11 is a schematic view and a calculation formula of depth of field according to an embodiment of the present invention.

FIG. 12 is an image processing software interface diagram according to an embodiment of the present invention.

Fig. 13 is a diagram showing evaluation results before image processing according to the embodiment of the present invention.

Fig. 14 is a diagram showing the evaluation result after the image processing according to the embodiment of the present invention.

FIG. 15 is a pictorial diagram of a system according to an embodiment of the present invention.

Reference numerals: the device comprises a light source 1, a colorimetric card 2, a concave lens 3, a convex lens 4, a diaphragm 5, a filter 6, an empty lens cone 7, an image acquisition circuit board 8, a dark box 9 and a computer 10.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

As shown in fig. 1, it is a schematic structural diagram of an imaging device of the present invention, which includes an optical compensation system module, an acquisition circuit module capable of acquiring an image, and a computer 10 capable of processing the image. The acquisition circuit module comprises an image acquisition circuit board 8 provided with a CMOS image sensor. The light emitted by the optical compensation system module is emitted to the acquisition circuit module, and the acquisition circuit module is connected to the computer 10. The model of the CMOS image sensor is MT9M 001. The pixels of the MT9M001 model CMOS image sensor are 130W, and the image information is lost or no image information can be acquired due to the fact that the image information is acquired by directly using the CMOS acquisition board, so that an optical system formed by combining an optical device such as a circuit acquisition board, a lens, an aperture and the like is required to be built to complete the acquisition of image photoelectric signals in cooperation with the CMOS image sensor, and the standard is realized.

In the imaging device, the optical compensation system module comprises a light source 1, a colorimetric card 2, a concave lens 3, a convex lens 4, a diaphragm 5, a filter 6, an empty lens cone 7 and a dark box 9. The light source 1, the colorimetric card 2, the concave lens 3, the convex lens 4, the diaphragm 5, the filter 6, the hollow lens cone 7 and the image acquisition circuit board 8 are all arranged inside the dark box 9. The color comparison card 2 is a standard color comparison card. The light source 1 is a ring light source distributed on the same side of the color comparison card 2. The light source 1 emits light to the color comparison card 2, and the light is reflected by the color comparison card 2 and then sequentially passes through the concave lens 3, the convex lens 4, the diaphragm 5, the filter 6 and the hollow lens cone 7. The convex lens 4 is made of K9 glass which is crystal clear and has good light transmission effect, and is widely used in the field of optical design.

Light passing through the hollow barrel 7 is emitted to the CMOS image sensor; the image acquisition circuit board 8 is connected with the computer 10 by using a USB data line. The computer 10 is mounted outside the dark box 9.

The design method of the imaging device comprises the design of the acquisition circuit module and the design of the optical compensation system module. The design of the acquisition circuit module comprises the step of designing image acquisition software by using a principle of extracting library functions and utilizing microsoft visual basic c + + software, wherein the image acquisition software is installed in the acquisition circuit module. The design process of each part is described in detail below with reference to the accompanying drawings.

Design of image acquisition circuit board 8

Fig. 2 is a block diagram of the structural design of the image acquisition circuit board 8. The processor of fig. 2, which uses an S3C2440 processor (ARM920T core), was developed by samsung electronics in korea, and has an interface most suitable for the present design, namely a camera interface, for low-cost, low-power, high-performance handheld devices or other electronic products, so that the CMOS processor does not need to be connected to a controller as the processor of the CCD image sensor. The protocol for controlling CMOS behavior similar to the I2C internal function, i.e., the two-wire serial protocol, which is a protocol specific to the RISC processor of 16/32, cannot be used directly in this processor, so that analog control must be performed via the I/0 pin of the processor while passing through the processor. And finally, the TCP/IP protocol is used for transmitting the image information acquired by the acquisition circuit board to the PC computer through the USB. The embedded acquisition board is not as powerful as a PC in terms of resources and functions, so that the PC must be used for complex processing, such as frequency domain transformation, etc.

Fig. 3 is a schematic diagram of the design of the image acquisition circuit board 8. Since the picture information to be received at the receiving end (image information processing and converting module) is 8 bits, and the data size of the image information output by the chip is 10 bits, the lower two bits of the sensor are removed in the schematic diagram.

Design of optical compensation system module

The design of the optical compensation system module adopts ZEMAX optical design software to design a light path, and comprises the steps of inputting the curvature radius, the optical wavelength and the view field parameters of a lens in the ZEMAX optical design software to obtain an optical structure model, optimizing the optical structure model to obtain designed optimized system parameters, and designing the light path according to the optimized system parameters.

Because the CMOS image sensor is directly used for collecting images, the size and the distance of the obtained images are limited, the position of a concave-convex lens in the structure of the Galileo telescope is changed by utilizing the principle of the Galileo telescope, such as a two-dimensional system image in fig. 4, namely, light rays firstly pass through the concave lens and then pass through the convex lens, so that a zoom-out and reduced virtual image can be obtained, and a larger range and a longer distance can be shot.

Optical design adopts ZEMAX to design the light path, and input lens's radius of curvature (concave lens's radius of curvature is 70, convex lens's is 30), wavelength (select F.D.C hydrogen spectrum series wavelength), parameters such as field of view, the selection is K9 glass, and this kind of glass is crystal clear and can play fine light transmission effect, is widely used for the optical design field. After setting these parameters, an optical structure model is obtained, for example, fig. 4 is a two-dimensional diagram of parameter setting and design, and then the optical model, i.e., parameters such as the distance between lenses, is optimized, for example, fig. 5 is an optical system evaluation function and wavelength setting interface.

The optical model can be optimized to obtain the focal length of the designed system, and the like, for example, fig. 6 is the optimized system data, and the focal length is 24.29565 cm.

After the optical system is set and optimized, whether the designed optical system achieves the optimal imaging effect needs to be detected. Two functions in ZEMAX were utilized: MTF (optical transfer function), Spot (dot plot), distortion. The modulation transfer function MTF is an objective evaluation tool for the imaging quality of an optical system, and reflects the modulation degree of each spatial frequency. T, S respectively represent the meridional and sagittal directions, the graphs of the MTF function before optimization are shown in fig. 7, the graphs after optimization are shown in fig. 8, the overall curve after optimization is higher, the MTF curve of the ideal model is a straight line with MTF of 1, the MTF curve cannot be a straight line in practice because the actual optical system is affected by aberration, the aberration is greatly affected, the curve is reduced, the higher the MTF curve is, the better the imaging effect is, and fig. 8 is the graph of the MTF function optimized to the best effect.

The MTF graph is analyzed, a dot column diagram can be analyzed, and when an Spt button in the ZEMAX page is selected, a viewing page of the dot column diagram can be entered, the dot column diagram expresses the size of a designed diffuse spot of the optical system, the diffuse spot is the size of an area of an image formed on an IMA (imaging plane) after light passes through the optical system, and can be viewed from a plurality of field angles, and the two diffuse spot diagrams shown in fig. 9 are viewed from a 0DEG field of view and a 4DEG field of view. The diffuse spot has a reference standard value, namely an Airy spot (Airy spot), wherein the Airy spot is the maximum bright spot of the central area of the diffraction pattern, and in the application of ZEMAX, the Airy Diam is 2.44, and the closer the value, the better the imaging effect is, such as 2.864 which is obtained from figure 9, and is the closest to the Airy spot standard value after optimization.

After the optical system is constructed, the focal length is 24mm, the diameter of the diffuse spot is 2.864, the aperture value is the focal length of the optical system divided by the maximum clear aperture, the clear aperture refers to the diameter of the clear part of the aperture, the clear aperture of the system is 23.5mm, and the aperture value of the system is F1. Since the distance from the convex lens to the imaging plane is 25.554155mm after optimization, as shown in fig. 10, this data is the image distance of the optical system, and is represented by the gaussian imaging formula: 1/u +1/v is 1/f, u is the object distance, v is the image distance, and f is the focal length, and the object distance can be found to be 60 cm.

Depth of field refers to a range of values in which an imaging device (e.g., a lens) can obtain a sharp image after focusing, and the range refers to a range in front of and behind an object to be measured. If the measured object is in the range, a clear image can be shot, and the image is fuzzy outside the range.

From the depth of field calculation formula, as can be obtained from fig. 11, the foreground depth of the designed optical compensation system is about 2cm, the rear depth of field is about 3cm, and the object to be photographed is placed at a distance of 60cm from the CMOS chip, and within a range of 2cm close to the CMOS chip and 3cm far from the CMOS chip, a clear image can be obtained.

Design of image processing software module

The design method further comprises the step of designing an image processing software module by utilizing micro soft visual c + + software by using the principle of extracting library functions, wherein the image processing software module is installed in the computer 10 and can sharpen the image.

After the acquisition circuit of the CMOS image sensor is manufactured and the optical compensation circuit is built, acquisition software is used for acquiring image information, and a simple window program capable of processing the acquired image is designed by adopting a micro visual c + +. The process of designing the software is as follows: creating project, project layout and function design, and writing program code.

The page of the image processing software after design is as shown in fig. 12, and the image processing software can perform operations such as scaling, brightness adjustment, color correction, text insertion, and filter on a picture.

The design mainly adopts a sharpening (sharpening) function in software, as shown in fig. 12, the fuzzy edge can be quickly focused, the part of the image needing to be processed has more granular sensation, the color brightness is increased, and the part is clearer. However, the sharpening is limited and must be moderate, and the sharpening over the head can cause the image to be unreal.

Fourth, image evaluation

The computer 10 also has iseetest software installed therein. The design method further comprises the step of evaluating the imaging device by using iseetest software, wherein the evaluation comprises single resolution evaluation and comparison evaluation. The single-item resolution evaluation takes the pixel and the resolution of single imaging of the imaging device before or after image processing as evaluation objects. The contrast evaluation takes the pixels imaged by the imaging device twice before and after image processing and resolution contrast as evaluation objects.

The evaluation takes a standard resolution test card as an image acquisition object; and during evaluation, one block of the central area of the standard resolution test card is intercepted to be used as an evaluation sample, and the shot image of the standard resolution test card is analyzed to judge the pixel and the resolution of the imaging device.

After the image is processed, the processed image needs to be evaluated to check whether the image processing has improved pixels and resolution. The image evaluation adopts the software of iSetest 4.0, and single resolution evaluation in the software is used, so that evaluation can be made only aiming at the pixel and the resolution of the image, and after the image acquired by the image acquisition system is subjected to image sharpening and other processing, the iSetest 4.0 is used for respectively evaluating the images before and after the image processing.

After the collection device is manufactured, a piece of the central area is intercepted to be used as an evaluation sample when a standard is judged and evaluated by using a resolution card, and the test card is certified by the international standard ISO 12233. The effective pixel of the image before evaluation image processing was 1236849, as in fig. 13, and the effective pixel of the image after evaluation image processing was 1580604, as in fig. 14. Illustrating that the image will be sharper with an improvement 343755 in the pixels after image processing.

Fifth, evaluation of images

The design method further comprises the step of debugging and detecting the imaging device according to the evaluation result after the imaging device is evaluated. The actual image of the system obtained by the manufacturing of the acquisition circuit of the CMOS image sensor, the construction of the optical compensation system, the design of the image processing software and the evaluation by using the image evaluation software is shown in FIG. 15.

The scheme is based on an MT9M001-CMOS image sensor lens imaging system. The whole system is divided into four parts:

the first part is designed for an acquisition circuit, and the first part is mainly an interface part of an acquisition circuit board and a bottom board circuit PCB.

The second part is the design of an optical compensation system, the second part adopts optical instruments such as lenses, diaphragms and the like, then a camera bellows is manufactured, and the optical instruments are combined together by utilizing the principle of optical design, so that the CMOS image sensor can acquire images with higher resolution.

The third part is the design of image acquisition software and image processing software, and the third part uses the principle of extracting library functions and is designed by utilizing microsoft visual c + + software.

And the fourth part is an image evaluation part which evaluates the processed image by using iseetest software and judges whether a better imaging effect is achieved or not by comparing the resolution of the shot image of the standard test card.

The invention designs specific parameters by using an MT9M001-cmos image sensor, k9 glass, a development board, a diaphragm and ZEMAX optical design software, builds a set of single lens imaging device, and can realize a higher-resolution imaging function on a standard colorimetric card.

While the above is directed to some, but not all embodiments of the invention, the detailed description of the embodiments of the invention is not intended to limit the scope of the invention, which is claimed, but is merely representative of selected embodiments of the invention. 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 (10)

1. An imaging apparatus, comprising an optical compensation system module, an acquisition circuit module capable of acquiring an image, and a computer (10) capable of processing the image; the acquisition circuit module comprises an image acquisition circuit board (8) provided with a CMOS image sensor; the light emitted by the optical compensation system module is emitted to the acquisition circuit module, and the acquisition circuit module is connected to the computer (10).

2. The imaging device according to claim 1, wherein the optical compensation system module comprises a light source (1), a color chart (2), a concave lens (3), a convex lens (4), a diaphragm (5), a filter (6) and an empty lens cone (7); the light source (1) emits light to the color comparison card (2), and the light is reflected by the color comparison card (2) and then sequentially passes through the concave lens (3), the convex lens (4), the diaphragm (5), the filter (6) and the hollow lens cone (7).

3. The imaging apparatus of claim 2, wherein the CMOS image sensor is of a model MT9M 001; light passing through the empty barrel (7) is emitted to the CMOS image sensor; the image acquisition circuit board (8) is connected with the computer (10) by using a USB data line.

4. The imaging apparatus according to claim 3, wherein the optical compensation system module further comprises a dark box (9); the light source (1), the colorimetric card (2), the concave lens (3), the convex lens (4), the diaphragm (5), the filter (6), the hollow lens cone (7) and the image acquisition circuit board (8) are all arranged in the dark box (9); the computer (10) is mounted outside the camera bellows (9).

5. An imaging apparatus design method according to any one of claims 1 to 4, wherein the design method includes design of an acquisition circuit module and design of an optical compensation system module; the design of the acquisition circuit module comprises the step of designing image acquisition software by using a principle of extracting library functions and utilizing microsoft visual basic c + + software, wherein the image acquisition software is installed in the acquisition circuit module.

6. The method of designing an imaging apparatus according to claim 5, characterized in that: the design of the optical compensation system module adopts ZEMAX optical design software to design an optical path, and comprises the steps of inputting the curvature radius, the optical wavelength and the view field parameters of a lens in the Zemax optical design software to obtain an optical structure model, optimizing the optical structure model to obtain designed optimized system parameters, and designing the optical path according to the optimized system parameters.

7. The method of designing an imaging apparatus according to claim 5, characterized in that: the design method further comprises the step of designing an image processing software module by utilizing micro soft visual c + + software by using the principle of extracting library functions, wherein the image processing software module is installed in the computer (10) and can sharpen the image.

8. The method of designing an imaging apparatus according to claim 7, characterized in that: the computer (10) is also provided with iseetest software; the design method further comprises evaluating the imaging device using iseetest software; the evaluation comprises single resolution evaluation and comparison evaluation;

the single-item resolution evaluation takes the pixel and the resolution of single imaging of the imaging device before or after image processing as evaluation objects;

the contrast evaluation takes the pixels imaged by the imaging device twice before and after image processing and resolution contrast as evaluation objects.

9. The method of designing an imaging apparatus according to claim 8, characterized in that: the evaluation takes a standard resolution test card as an image acquisition object; and during evaluation, one block of the central area of the standard resolution test card is intercepted to be used as an evaluation sample, and the shot image of the standard resolution test card is analyzed to judge the pixel and the resolution of the imaging device.

10. The method of designing an imaging apparatus according to claim 9, characterized in that: the design method further comprises the step of debugging and detecting the imaging device according to the evaluation result after the imaging device is evaluated.

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