CN107131956B - A kind of full-automatic image-type sky polarized light test system - Google Patents

Abstract

The invention provides a fully automatic image-type sky polarized light testing system, which belongs to the technical field of optical and electronic testing, and is particularly suitable for collecting sky light polarization mode data in weak light environments. The test system mainly includes a polarizer rotation mechanism, a SLR camera, a fisheye lens, upper and lower support plate brackets and a single-chip microcomputer development board. Timer 0 of the microcontroller development board controls the generation of PWM waves, thereby controlling the stepper motor to achieve precise positioning. Timer 1 controls camera exposure according to the exposure time given in the exposure array. Timer 2 controls the collection waiting time of adjacent data groups according to the given data collection interval. The invention has the characteristics of simple structure, small volume, high degree of full automation and the like. The present invention has unique advantages when collecting polarized pattern data of moonlight in a field environment.

Description

A fully automatic image-type sky polarized light test system

technical field

The invention is a fully automatic image-type sky polarized light testing system, which belongs to the technical field of optical and electronic testing, and is suitable for testing the polarization mode of sky light, especially for testing the polarization mode of moonlight under weak light conditions.

Background technique

At present, the test systems for the distribution pattern of polarized light in the sky mainly include image-type and point-source test systems. Although the point source test system can accurately test the polarization mode of a specific point in the sky, it has the disadvantages of continuously adjusting the test altitude and azimuth angle, poor positioning accuracy, long test time, and large errors. Therefore, the image-type test system that can quickly acquire the polarization mode of the whole sky with a large viewing angle is widely used. However, the existing image-type polarized light test system has problems such as large volume, low degree of automation, inconvenient portability, and inability to collect moonlight polarization modes other than the full moon. In view of this, when collecting a large amount of polarized light distribution pattern data in the sky, a portable and fully automatic polarized light testing system that can be applied in low-light environments is particularly important.

Among the existing schemes of polarized light testing instruments at home and abroad, some scholars have put forward three polarizer schemes with three cameras, three lenses and one lens, but these two schemes have the disadvantages of bloated devices and low degree of automation. The automatic detection device of sky light polarization mode designed by Zhao Kaichun et al. cannot solve the problem of low imaging quality caused by long-time exposure of the electronic shutter of industrial cameras and the reflection problems caused by light obliquely entering the light-shielding tube.

Contents of the invention

The technical problem to be solved by the invention is to solve the problem of low imaging quality caused by long-time exposure of industrial cameras by using the high imaging performance of a single-lens reflex camera. The exposure of the SLR camera and the rotation of the stepper motor are controlled by the single-chip microcomputer development board to realize the automatic operation of the test system, and at the same time, the miniaturization of the test system is realized without the control of the upper computer. A polarizer bracket is added to the front end of the fisheye lens to solve the problem of reflection of polarized light before entering the lens.

Technical scheme of the present invention:

A fully automatic image-type sky polarized light testing system, the polarizer 1 is placed on the front end of the fisheye lens 4 through the polarizer bracket 2, and is used to generate linearly polarized light from part of the polarized light in the sky, which can be changed by rotating the polarizer bracket 2 The position of the main optical axis of the polarizer 1 changes the polarization direction of the linearly polarized light incident on the fisheye lens 4; the polarizer bracket 2 is installed on the hollow shaft 3 to carry the linear polarizer 1 and prevent the light from obliquely entering Scattered light due to diffuse scattering behind the polarizer enters the lens, thus ensuring the quality of the collected data. The hollow shaft 3 is connected with the polarizer bracket 2, and the rotation of the hollow shaft 3 drives the rotation of the polarizer bracket 2 and the polarizer 1. At the same time, the hollow shaft 3 prevents the external non-polarized light from entering the fisheye lens 4 and plays a role of shading; the gear set 5 It is a pair of large and small gears, wherein the large gear is a driven wheel, which is connected together with the hollow shaft 3 through a flat key, and the small gear is used as a driving wheel to drive the large gear to rotate, converting the motion of the stepping motor 15 into the action of the polarizer 1; the bearing Group 6 is installed between the hollow shaft 3 and the upper support plate 12 and the lower support plate 14 to ensure that the hollow shaft can rotate smoothly and accurately; the upper support plate 12 and the lower support plate 14 are connected together by a support column 13 to support the Revolving shaft 3, gear set 5 and bearing set 6; stepper motor 15 drives gear set 5 to rotate, and makes the main optical axis of polarizer 1 rotate 0 ^° , 45 ^° , 90 ^° in turn when collecting each set of data, and makes the polarization The main optical axis of sheet 1 can be positioned at 0 ^° , 45 ^° and 90 ^° with high precision; the upper and lower support plate brackets 7 connect the lower support plate 14 and the quick-release plate 8 through fixing bolts 16, and use To adjust the relative position of the polarizer 1 and the fisheye lens 4, so as to ensure that the main optical axis of the fisheye lens coincides with the rotation axis of the polarizer; the quick release plate 8 connects the upper and lower support plate brackets 7 and the SLR camera 9 through fixing bolts 16 Together; SLR camera 9 for collecting polarized pattern data of moonlight. The SLR camera shutter control switch 10 is connected with the camera shutter control port of the single-chip microcomputer development board 17 and the shutter line interface of the SLR camera 9, and controls the opening and closing of the camera shutter according to the instruction of the single-chip microcomputer development board 17. The single-chip microcomputer development board 17 is connected with the stepping motor 15 and the shutter control switch 10 of the SLR camera to control the exposure time of the SLR camera and the angle at which the stepping motor rotates each time when collecting data. The 5V single-chip microcomputer development board battery 11 is the power supply for the single-chip microcomputer, and the 24V stepping motor battery 18 is the driving power of the stepping motor, and they can guarantee the uninterrupted work of the test system for 24 hours.

When the test system is working, the running indicator is always on, and when the test system is in the data collection interval, the data collection interval indicator flashes. The timer 0 of the microcontroller development board controls the generation of PWM waves, and then controls the stepper motor through the stepper motor control port to achieve precise positioning. When collecting each set of data, timer 1 of the microcontroller development board controls the exposure time of the camera through the camera shutter control port according to the given exposure time in the exposure array. The timer 2 of the development board controls the waiting time for collecting the next set of data according to the given data collection interval. According to the difference in the illuminated area of the moon or the difference in the light intensity of the external environment when collecting data, different camera exposure time arrays are selected to ensure the quality of the collected image data. When collecting data, the data is collected in groups, and each group of data contains three picture data, which are the skylight polarization mode data when the main optical axis of the polarizer is at 0 ^° , 45 ^° , and 90 ^° respectively.

Description of drawings

Fig. 1 is a schematic diagram of the system composition of the present invention.

Fig. 2 is a schematic diagram of the position and rotation of the polarizer when the SLR camera of the present invention collects data.

Fig. 3 is a working flow diagram of the present invention.

In the figure: 1 polarizer; 2 polarizer holder; 3 hollow shaft; 4 fisheye lens; 5 gear set;

6 bearing group; 7 upper and lower support plate bracket; 8 quick release plate; 9 SLR camera;

10 SLR camera shutter control switch; 11 5V microcontroller development board battery; 12 upper support board;

13 support column; 14 lower support plate; 15 stepping motor; 16 fixing bolt; 17 MCU development board;

18 24V stepper motor batteries.

Detailed ways

The specific implementation manners of the present invention will be further described below in conjunction with the accompanying drawings and technical solutions.

As shown in Figure 1, the present invention includes a polarizer 1, a polarizer bracket 2, a hollow shaft 3, a fisheye lens 4, a gear set 5, a bearing set 6, an upper and lower support plate bracket 7, a quick release plate 8, a single-lens reflex camera 9, Camera shutter control switch 10, 5V single-chip microcomputer development board battery 11, upper support plate 12, support column 13, lower support plate 14, stepping motor 15, fixing bolt 16, single-chip microcomputer development board 17 and 24V stepping motor battery 18. The polarizer, polarizer bracket, hollow shaft, gear set, bearing set, upper support plate, support column, lower support plate, and stepping motor form the polarizer rotation mechanism, and the single-chip microcomputer development board is used to control the operation of the system. When it is necessary to collect moonlight polarization mode data, select the appropriate SLR camera exposure array according to the time period of data collection, the time interval of each group of data and the illuminated area of the moon, compile the selected exposure array into the single-chip computer program, and use this The single-chip microcomputer program is burnt to the single-chip microcomputer development board to control the operation of the system. Then connect the shutter control switch of the SLR camera to the shutter interface of the SLR camera and the camera shutter switch control port of the single-chip microcomputer development board, and then connect the control signal line of the stepping motor to the PWM wave output port of the single-chip microcomputer, and then connect the automatic image sky The polarized light test system is installed on the tripod, and the optical axis of the fisheye lens 4 is aligned with the zenith. Turn on the power switches of the SLR camera, single-chip microcomputer and stepping motor respectively, and then you can prepare to collect the polarization mode data of the sky light in the front view angle of the fisheye lens.

The working flow chart of the present invention is as shown in Figure 3, install the test system, make the optical axis of the fisheye lens align with the zenith, and open all power switches. Press the Enter key on the MCU development board, wait for 5 seconds, the system runs normally, the running indicator lights up, the adjacent data group collection waiting interval indicator light flashes, and the data collection interval timing starts at the same time. At this time, the polarizer is at the initial position, that is, the position of 0 ^° , and the single-chip microcomputer sends an instruction to the shutter control switch of the SLR camera to make the SLR camera collect the first photo in the first set of data. After the collection is completed, the single-chip microcomputer controls the stepping motor to rotate 90 ^° , so that the polarizer rotates 45 ^° as shown in Figure 2. At this time, the main optical axis of the polarizer is at a position of 45 ^° , and the SLR camera collects the second photo in the first set of data. After the acquisition is completed, the single-chip microcomputer controls the stepper motor to rotate 90 ^° again, so that the polarizer rotates 45 ^° as shown in figure 2. At this time, the main optical axis of the polarizer is at 90 ^° , and the SLR camera collects the third photo in the first set of data. After the acquisition is completed, the single-chip microcomputer controls the stepping motor to continue to rotate 540 ^° , so that the polarizer returns to the initial position, which is 0 ^° position. The MCU program continues to run, waiting for the data group acquisition interval time controlled by the timer 2 of the MCU development board to end, and the exposure time array pointer points to the camera exposure time required to collect the next set of data. The timer 1 of the single-chip microcomputer development board controls the length of the camera exposure time according to the exposure time array pointer pointing to the exposure time, and the camera shutter control port of the single-chip microcomputer controls the SLR camera to collect the second set of data through the SLR camera shutter switch. When collecting the second set of data, as with the first set of data, the timer 0 of the MCU development board controls the generation and stop of the PWM wave so that the stepper motor rotates three times, and drives the main optical axis of the polarizer to rotate to 0 ^° , 45 ^° and 90 ^° positions. The SLR camera sequentially collects three photos when the main optical axis of the polarizer is at 0 ^° , 45 ^° and 90 ^° . After that, the single-chip program control system continues to run, and the system waits for the end of the given data group collection interval time, and then continues to collect the next group of data. When it is necessary to stop collecting data, press the Esc key on the development board, and the automatic image sky polarized light test system will stop running. When the light intensity of the external environment where the data is collected changes, the new data collection task can be completed by changing the exposure time value and the data group collection interval in the program on the development board.

Claims (1)

1. A full-automatic image-type sky polarized light test system is characterized in that the polarizer (1) is placed on the front end of the fisheye lens (4) by a polarizer bracket (2), and is used to partially polarize the sky in the sky Generate linearly polarized light, change the position of the main optical axis of the polarizer (1) by rotating the polarizer holder (2), so that the polarization direction of the linearly polarized light incident on the fisheye lens (4) is changed; the polarizer holder (2) Installed on the hollow rotating shaft (3), it is used to carry the polarizer (1), and at the same time prevents the scattered light caused by diffuse scattering from entering the fisheye lens (4) after the light obliquely enters the polarizer (1), so as to ensure the quality of collected data; The hollow shaft (3) is connected with the polarizer bracket (2), and the rotation of the hollow shaft (3) drives the rotation of the polarizer bracket (2) and the polarizer (1), and at the same time, the hollow shaft (3) prevents external non-polarized light from entering the fisheye lens (4) plays the role of shading; the gear set (5) is a pair of large and small gears, wherein the large gear is a driven wheel, which is connected together with the hollow shaft (3) through a flat key, and the small gear is used as a driving wheel to drive the large gear to rotate , the motion of the stepper motor (15) is converted into the action of the polarizer (1); the bearing group (6) is installed between the hollow shaft (3) and the upper support plate (12) and the lower support plate (14), ensuring The hollow shaft rotates smoothly and accurately; the upper support plate (12) and the lower support plate (14) are connected together through the support column (13) to support the hollow shaft (3), the gear set (5) and the bearing set (6) The stepping motor (15) drives the gear set (5) to rotate, and the polarizer (1) is rotated 0°, 45°, 90° successively when collecting each group of data, and the main optical axis of the polarizer (1) is Higher precision is positioned at 0°, 45° and 90°; the upper and lower support plate brackets (7) connect the lower support plate (14) and the quick release plate (8) together through fixing bolts (16), and use To adjust the relative position of the polarizer (1) and the fisheye lens (4), ensure that the main optical axis of the fisheye lens (4) coincides with the rotation axis of the polarizer (1); Plate support (7) and SLR camera (9) are connected together by fixing bolt (16); SLR camera (9), is used to collect the polarization mode data of moonlight; SLR camera shutter control switch (10), and single-chip microcomputer development board ( The camera shutter control port of 17) is connected with the shutter line interface of the SLR camera (9), and controls the opening and closing of the camera shutter according to the instruction of the single-chip microcomputer development board (17); the single-chip microcomputer development board (17), connects the stepper motor (15) And SLR camera shutter control switch (10), control the exposure time of SLR camera and the angle that stepper motor rotates each time when collecting data each time; ) is the driving power of the stepping motor.