A dynamic visual sensor dynamic range test system and method

Abstract

The application discloses a dynamic visual sensor dynamic range test system and method, and relates to the field of dynamic visual sensors.The system comprises a light source, a polarizer, a spatial light modulator, a controller, a computer, a polarizer and a dynamic visual sensor to be tested.The application uses the spatial light modulator as a core test device, modulates the light intensity of the input monochromatic parallel light by using the spatial light modulator, obtains the accurate output light intensity, irradiates the dynamic visual sensor to be tested, calculates the maximum light intensity and the minimum light intensity that can be detected by the dynamic visual sensor, and finally obtains the dynamic range of the dynamic visual sensor.The application can accurately adjust the light intensity change irradiated to the dynamic visual sensor, avoids the problem that it is difficult to use the absolute value of the gray scale or the full well to calculate the dynamic range by the charge accumulation test of the dynamic visual sensor, and enables the dynamic visual sensor to accurately and quantitatively test the dynamic range of the dynamic visual sensor under the condition that the charge cannot be accumulated.

Description

Technical Field

[0001] This invention relates to the field of dynamic vision sensor technology, and specifically to a dynamic vision sensor dynamic range testing system and method. Background Technology

[0002] Inspired by biological vision, the pixels of dynamic vision sensors are mainly divided into three levels: a voltage-to-current logarithmic conversion unit, a change amplification unit, and a comparison unit. An event occurs when the intensity of light projected onto a pixel changes, causing the pixel to generate a pulse signal. This signal is then represented digitally via Address Event Representation (AER) and transmitted through the chip's output circuit. Each event includes information such as pixel coordinates, a timestamp, and the polarity of the light intensity change. Traditional image sensors, on the other hand, accumulate photogenerated charge and convert it into voltage for quantization. The dynamic range of a traditional image sensor depends on the maximum light energy it can detect and the light energy for which the output signal-to-noise ratio (SNR) equals 1. The maximum light energy detectable depends on the sensor's full-well charge, while the light energy for which the output SNR equals 1 depends on the readout noise. Therefore, the dynamic range of a traditional image sensor is the ratio of the full-well charge minus the dark charge to the readout noise. Testing is also performed by measuring these indicators and then calculating the dynamic range. However, dynamic vision sensors lack a charge potential well, and they do not produce output under constant light intensity. This renders traditional dynamic range testing methods for image sensors unsuitable for dynamic vision sensors. Dynamic range testing of dynamic vision sensors requires a light source whose intensity can change rapidly. Accurately altering the output light intensity triggers a response from the dynamic vision sensor, allowing testing of the minimum and maximum light intensities at which the sensor's output signal-to-noise ratio equals 1 in response to changes in light intensity.

[0003] Currently, there are no specific and effective solutions to the above-mentioned needs, nor have any relevant methods and equipment been found for testing the dynamic range of dynamic vision sensors. Summary of the Invention

[0004] To address the problems in dynamic range testing of existing dynamic vision sensors, this invention provides a dynamic vision sensor dynamic range testing system and method.

[0005] The technical solution adopted by this invention to solve the technical problem is as follows:

[0006] The present invention provides a dynamic range testing system for dynamic vision sensors, comprising:

[0007] A light source used to emit monochromatic parallel light;

[0008] A polarizer is used to adjust the polarization direction of monochromatic parallel light.

[0009] A spatial light modulator is used to modulate monochromatic parallel light after it has been adjusted by a polarizer. The polarization direction of the monochromatic parallel light is at a 45-degree angle to the alignment direction of the liquid crystal molecules in the spatial light modulator after the polarizer is adjusted.

[0010] An analyzer is used to detect modulated monochromatic parallel light, wherein the polarization direction of the polarizer is perpendicular to the polarization direction of the analyzer.

[0011] The dynamic vision sensor under test is used to image the monochromatic parallel light detected by the analyzer and form a light spot image;

[0012] A controller connected to a spatial light modulator is used to change the modulation phase of the spatial light modulator;

[0013] The computer, which is connected to both the controller and the dynamic vision sensor under test, is used to send control commands to the controller and to receive and display the light spot image sent by the dynamic vision sensor under test.

[0014] The present invention provides a method for testing the dynamic range of a dynamic vision sensor, implemented using the dynamic vision sensor dynamic range testing system described herein; the method includes the following steps:

[0015] Step S1: Statistically analyze the background activity noise of the tested dynamic vision sensor under low brightness.

[0016] Step S2: Determine the minimum light intensity at which the output signal-to-noise ratio of the dynamic vision sensor under test is equal to 1 when stimulated by changes in light intensity;

[0017] Step S3: Statistically analyze the background activity noise of the tested dynamic vision sensor under high brightness;

[0018] Step S4: Determine the maximum light intensity at which the output signal-to-noise ratio of the dynamic vision sensor under test is equal to 1 when stimulated by changes in light intensity;

[0019] Step S5: Change the light source to a different wavelength, repeat steps S1-S4, and calculate the minimum and maximum light intensity at different wavelengths.

[0020] Step S6: Calculate the dynamic range of the dynamic vision sensor under test using the minimum and maximum light intensities at different wavelengths.

[0021] Furthermore, the specific operation steps of step S1 are as follows:

[0022] Monochromatic parallel light of known wavelength is emitted as input, and the intensity of this monochromatic parallel light is known and set to a relatively weak intensity. The polarizer is adjusted so that the polarization direction of the incident monochromatic parallel light forms a 45-degree angle with the alignment direction of the liquid crystal molecules in the spatial light modulator. The incident monochromatic parallel light passes sequentially through the spatial light modulator and analyzer before entering the focal plane of the dynamic vision sensor under test, forming a light spot image. An event stream is acquired, and the occurrence frequency f of the average background activity noise of the dynamic vision sensor under test at the current light intensity is calculated. BAL :

[0023]

[0024] Where, N ESL For the total number of events in this event stream, t L For the duration of this event stream, w is the lateral resolution of the focal plane of the dynamic vision sensor under test, and h is the longitudinal resolution of the focal plane of the dynamic vision sensor under test.

[0025] Furthermore, the specific operation steps of step S2 are as follows:

[0026] The computer sends control commands to the controller, which then changes the modulation phase of the spatial light modulator according to the commands. By adjusting the grayscale values ​​of the phase map loaded on the spatial light modulator, the output light intensity on the dynamic vision sensor under test is gradually reduced. The entire process of event streaming is collected to determine the event frequency generated by light intensity changes at different brightness levels. When this event frequency is 2f... BAL At this point, the change in light intensity is the minimum light intensity L at which the signal-to-noise ratio of the output of the dynamic vision sensor under test equals 1 when stimulated by the change in light intensity. L .

[0027] Furthermore, the specific operation steps of step S3 are as follows:

[0028] Monochromatic parallel light of known wavelength is emitted as input, and the intensity of this monochromatic parallel light is known and can be set to a relatively strong intensity. The polarizer is adjusted so that the polarization direction of the incident monochromatic parallel light 7 forms a 45-degree angle with the alignment direction of the liquid crystal molecules in the spatial light modulator. The incident monochromatic parallel light passes through the spatial light modulator and analyzer in sequence and finally enters the focal plane of the dynamic vision sensor under test to form a light spot image. Event stream is acquired, and the occurrence frequency f of the average background activity noise of the dynamic vision sensor under test at the current light intensity is calculated. BAH :

[0029]

[0030] Where, N ESH For the total number of events in this event stream, t HFor the duration of this event stream, w is the lateral resolution of the focal plane of the dynamic vision sensor under test, and h is the longitudinal resolution of the focal plane of the dynamic vision sensor under test.

[0031] Furthermore, the specific operation steps of step S4 are as follows:

[0032] The computer sends control commands to the controller, which then changes the modulation phase of the spatial light modulator according to the commands. By adjusting the grayscale values ​​of the phase map loaded on the spatial light modulator, the output light intensity on the dynamic vision sensor under test is gradually changed. The entire process of event streaming is collected, and the event frequency generated by the light intensity changes under different brightness levels is determined. When this event frequency is 2f... BAH At this point, the change in light intensity is the maximum light intensity L at which the dynamic vision sensor being measured outputs a signal-to-noise ratio equal to 1 when stimulated by the change in light intensity. H .

[0033] Furthermore, the specific operation steps of step S5 are as follows:

[0034] By changing the light source to different wavelengths, repeat steps S1-S4 to calculate the minimum light intensity L at different wavelengths. LN and maximum light intensity L HN N is 1, 2, 3...M, where M is a positive integer.

[0035] Furthermore, the specific operation steps of step S6 are as follows:

[0036] Using the minimum light intensity L at different wavelengths LN and maximum light intensity L HN Calculate the dynamic range of the tested dynamic vision sensor:

[0037] The beneficial effects of this invention are:

[0038] The present invention discloses a dynamic range testing system and method for a dynamic vision sensor, which uses a spatial light modulator as the core testing device. The spatial light modulator modulates the intensity of the input monochromatic parallel light to obtain a precise output light intensity that illuminates the dynamic vision sensor under test. The maximum and minimum light intensities that the dynamic vision sensor can detect are calculated, and finally the dynamic range of the dynamic vision sensor is obtained.

[0039] The present invention provides a dynamic range testing system and method for a dynamic vision sensor, which can precisely adjust the changes in light intensity illuminating the dynamic vision sensor. The dynamic vision sensor generates pulses in response to the changes in light intensity, eliminating the need for charge accumulation. This avoids the problem of difficulty in calculating the dynamic range using the absolute value of grayscale or full-well in testing the dynamic range of a dynamic vision sensor through charge accumulation. It enables the dynamic range of the dynamic vision sensor to be accurately and quantitatively tested under conditions where charge accumulation is not possible, and has the advantages of accurate testing and high testing efficiency. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the dynamic range testing system for a dynamic vision sensor according to the present invention.

[0041] Figure 2 This is the output light intensity variation curve on the dynamic vision sensor under test.

[0042] Figure 3 This is a flowchart of a dynamic range testing method for a dynamic vision sensor according to the present invention.

[0043] In the diagram, 1 is a polarizer, 2 is a spatial light modulator, 3 is a controller, 4 is a computer, 5 is an analyzer, 6 is the dynamic vision sensor under test, 7 is monochromatic parallel light, and 8 is a light source. Detailed Implementation

[0044] The present invention will be further described in detail below with reference to the accompanying drawings.

[0045] See Figure 1 The present invention provides a dynamic range testing system for a dynamic vision sensor, mainly comprising: a light source 8, a polarizer 1, a spatial light modulator 2, a controller 3, a computer 4, an analyzer 5, and a dynamic vision sensor 6 under test. The polarizer 1 is positioned at the front end of the spatial light modulator 2, and the analyzer 5 is positioned at the rear end of the spatial light modulator 2. Furthermore, the polarization direction of the polarizer 1 is perpendicular to the polarization direction of the analyzer 5. Simultaneously, the controller 3 is connected to the spatial light modulator 2 via a cable, and the controller 3 changes the modulation phase of the spatial light modulator 2. The controller 3 is also connected to the computer 4 via a cable, and the computer 4 sends control commands to the controller 3. The dynamic vision sensor 6 under test is positioned at the rear end of the analyzer 5 and is connected to the computer 4 via a cable.

[0046] The dynamic range testing system for a dynamic vision sensor of the present invention operates on the following principle:

[0047] Light source 8 emits monochromatic parallel light 7. The polarization direction of the incident monochromatic parallel light 7 is adjusted by adjusting the direction of polarizer 1, so that the polarization direction of the incident monochromatic parallel light 7 forms a 45-degree angle (θ = 45°) with the alignment direction of the liquid crystal molecules in spatial light modulator 2. The incident monochromatic parallel light 7 passes through spatial light modulator 2 and analyzer 5 in sequence and finally enters the focal plane of the dynamic vision sensor 6 under test to form a light spot image, which is then uploaded to computer 4 for display. Then, the incident monochromatic parallel light 7 is modulated. First, computer 4 sends a control command to controller 3. Controller 3 changes the modulation phase of spatial light modulator 2 according to the control command. By adjusting the gray value of the phase map loaded on spatial light modulator 2, the light intensity on the dynamic vision sensor 6 under test changes with the change of the gray value of the phase map. The output light intensity change curve on the dynamic vision sensor 6 under test is shown in the figure. Figure 2 As shown in the figure, the horizontal axis represents the grayscale value of the phase map (0-256), and the vertical axis represents the normalized light intensity (0-1) on the dynamic vision sensor 6 under test. Therefore, by adjusting the grayscale value of each pixel of the phase map loaded on the spatial light modulator 2, the light intensity at the corresponding position of each pixel in the light spot image on the dynamic vision sensor 6 under test can be directly and accurately adjusted.

[0048] In this implementation, polarizer 1 can specifically be LPVISA050, but is not limited to it.

[0049] In this implementation, the spatial light modulator 2 may specifically be a silicon-based liquid crystal spatial light modulator, but is not limited to this.

[0050] In this implementation, the analyzer 5 can specifically be an LPVISA050, but is not limited to it.

[0051] See Figure 3 The present invention provides a dynamic range testing method for a dynamic vision sensor, implemented using the aforementioned dynamic range testing system. The main steps of this method include: statistically analyzing the background activity noise of the tested dynamic vision sensor 6 under low brightness; and determining the minimum light intensity L at which the output signal-to-noise ratio of the tested dynamic vision sensor 6 is equal to 1 when stimulated by changes in light intensity. L →Statistical analysis of background activity noise of the tested dynamic vision sensor 6 under high brightness →Determine the maximum light intensity L at which the tested dynamic vision sensor 6 outputs a signal-to-noise ratio equal to 1 when stimulated by changes in light intensity. H → Replace the light source with a different wavelength 8, repeat the above four steps, and calculate the minimum light intensity L at different wavelengths. LN and maximum light intensity L HN →Utilizing the minimum light intensity L at different wavelengths LN and maximum light intensity L HN Calculate the dynamic range of the tested dynamic vision sensor 6.

[0052] Step S1: Analyze the background activity noise of the tested dynamic vision sensor 6 under low brightness conditions; the specific operation steps are as follows:

[0053] Monochromatic parallel light 7 emitted from a light source 8 of known wavelength is used as input. The intensity of this monochromatic parallel light 7 is known and can be set to a relatively weak intensity (approximately 1 Lux) for ease of operation. Polarizer 1 is adjusted so that the polarization direction of the incident monochromatic parallel light 7 forms a 45-degree angle (θ = 45°) with the alignment direction of the liquid crystal molecules in the spatial light modulator 2. The incident monochromatic parallel light 7 passes sequentially through the spatial light modulator 2 and the analyzer 5 before finally incident on the focal plane of the dynamic vision sensor 6 under test, forming a light spot image. Event streams are acquired, and the occurrence frequency f of the average background activity noise of the dynamic vision sensor 6 under test at the current light intensity is calculated. BAL :

[0054]

[0055] Where, N ESL For the total number of events in this event stream, t L For the duration of this event stream, w represents the lateral resolution of the 6-focal plane of the dynamic vision sensor under test, and h represents the longitudinal resolution of the 6-focal plane of the dynamic vision sensor under test.

[0056] Step S2: Determine the minimum light intensity L at which the output signal-to-noise ratio of the dynamic vision sensor 6 under test equals 1 when stimulated by changes in light intensity. L The specific operating steps are as follows:

[0057] Computer 4 sends control commands to controller 3. Controller 3 changes the modulation phase of spatial light modulator 2 according to the control commands. By adjusting the grayscale value of the phase map loaded on spatial light modulator 2, the output light intensity on the dynamic vision sensor 6 under test is gradually reduced. The entire process event stream is collected, and the event frequency generated by the light intensity change under different brightness levels is determined. When this event frequency is 2f... BAL At this point, the change in light intensity is the minimum light intensity L at which the signal-to-noise ratio of the output of the dynamic vision sensor 6 under test is equal to 1 when stimulated by the change in light intensity. L .

[0058] Step S3: Analyze the background activity noise of the tested dynamic vision sensor 6 under high brightness conditions; the specific operation steps are as follows:

[0059] Monochromatic parallel light 7 emitted from a light source 8 of known wavelength is used as input. The intensity of this monochromatic parallel light 7 is known and can be set to a relatively strong intensity (approximately 10,000 Lux), making it easy to operate. Polarizer 1 is adjusted so that the polarization direction of the incident monochromatic parallel light 7 forms a 45-degree angle (θ = 45°) with the alignment direction of the liquid crystal molecules in the spatial light modulator 2. The incident monochromatic parallel light 7 passes sequentially through the spatial light modulator 2 and the analyzer 5 before finally incident on the focal plane of the dynamic vision sensor 6 under test, forming a light spot image. Event streams are acquired, and the occurrence frequency f of the average background activity noise of the dynamic vision sensor 6 under test at the current light intensity is calculated. BAH :

[0060]

[0061] Where, N ESH For the total number of events in this event stream, t H For the duration of this event stream, w represents the lateral resolution of the 6-focal plane of the dynamic vision sensor under test, and h represents the longitudinal resolution of the 6-focal plane of the dynamic vision sensor under test.

[0062] Because the dynamic vision sensor 6 under test is exposed to strong light intensity, it is greatly affected by the flash noise of light, and the background activity noise will increase. Therefore, it is necessary to measure the frequency of occurrence of the average background activity noise of the dynamic vision sensor 6 under the current light intensity.

[0063] Step S4: Determine the maximum light intensity L at which the output signal-to-noise ratio of the dynamic vision sensor 6 under test is equal to 1 when stimulated by changes in light intensity. H The specific operating steps are as follows:

[0064] Computer 4 sends control commands to controller 3. Controller 3 changes the modulation phase of spatial light modulator 2 according to the control commands. By adjusting the grayscale value of the phase map loaded on spatial light modulator 2, the output light intensity on the dynamic vision sensor 6 under test is gradually changed. The entire process event stream is collected, and the event frequency generated by the light intensity change under different brightness levels is determined. When this event frequency is 2f... BAH At this time, the change in light intensity is the maximum light intensity L at which the dynamic vision sensor 6, stimulated by the change in light intensity, outputs a signal-to-noise ratio equal to 1. H .

[0065] Step S5: Replace the light source 8 with a different wavelength, repeat steps S1-S4, and calculate the minimum light intensity L at different wavelengths. LN and maximum light intensity L HN , where N is 1, 2, 3...M, and M is a positive integer.

[0066] Step S6: Utilize the minimum light intensity L at different wavelengths LN and maximum light intensity L HNCalculate the dynamic range of the tested dynamic vision sensor 6: Furthermore, the formula for calculating the dynamic range of the tested dynamic vision sensor 6 can also be a ratio rather than a logarithmic one, specifically as follows:

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dynamic range testing system for a dynamic vision sensor, characterized in that, include: A light source used to emit monochromatic parallel light; A polarizer is used to adjust the polarization direction of monochromatic parallel light. A spatial light modulator is used to modulate monochromatic parallel light after it has been adjusted by a polarizer. The polarization direction of the monochromatic parallel light is at a 45-degree angle to the alignment direction of the liquid crystal molecules in the spatial light modulator after the polarizer is adjusted. An analyzer is used to detect modulated monochromatic parallel light, wherein the polarization direction of the polarizer is perpendicular to the polarization direction of the analyzer. The dynamic vision sensor under test is used to image the monochromatic parallel light detected by the analyzer and form a light spot image; A controller connected to a spatial light modulator is used to change the modulation phase of the spatial light modulator; The computer, which is connected to both the controller and the dynamic vision sensor under test, is used to send control commands to the controller and to receive and display the light spot image sent by the dynamic vision sensor under test.

2. A method for testing the dynamic range of a dynamic vision sensor, characterized in that, This is achieved using the dynamic range testing system for a dynamic vision sensor as described in claim 1; the method includes the following steps: Step S1: Statistically analyze the background activity noise of the tested dynamic vision sensor under low brightness. Step S2: Determine the minimum light intensity at which the output signal-to-noise ratio of the dynamic vision sensor under test is equal to 1 when stimulated by changes in light intensity; Step S3: Statistically analyze the background activity noise of the tested dynamic vision sensor under high brightness; Step S4: Determine the maximum light intensity at which the output signal-to-noise ratio of the dynamic vision sensor under test is equal to 1 when stimulated by changes in light intensity; Step S5: Change the light source to a different wavelength, repeat steps S1-S4, and calculate the minimum and maximum light intensity at different wavelengths. Step S6: Calculate the dynamic range of the dynamic vision sensor under test using the minimum and maximum light intensities at different wavelengths.

3. The method for testing the dynamic range of a dynamic vision sensor according to claim 2, characterized in that, The specific steps of step S1 are as follows: The monochromatic parallel light with known light intensity is emitted by using a light source with known wavelength as input, and the known light intensity is set as a weak light intensity; the polarizer is adjusted so that the polarization direction of the incident monochromatic parallel light forms a 45-degree angle with the liquid crystal molecule arrangement direction in the spatial light modulator; the incident monochromatic parallel light is sequentially incident to the focal plane of the measured dynamic vision sensor to form a spot image after passing through the spatial light modulator and the polarizer; the event stream is collected, and the occurrence frequency f of the average background activity noise of the measured dynamic vision sensor under the current light intensity is calculated BAL : where N ESL is the total number of events in the event stream, t L is the length of the event stream, w is the lateral resolution of the focal plane of the dynamic vision sensor under test, and h is the longitudinal resolution of the focal plane of the dynamic vision sensor under test.

4. The method for testing the dynamic range of a dynamic vision sensor according to claim 3, characterized in that, The specific steps of step S2 are as follows: The control instruction is sent to the controller by computer, the controller changes the modulation phase of the spatial light modulator according to the control instruction, the output light intensity on the measured dynamic vision sensor is gradually reduced by adjusting the gray value of the phase map loaded on the spatial light modulator, the whole process event stream is collected, and the event frequency generated by the light intensity change under different brightness is determined BAL When the event frequency is 2f L , the light intensity at this time is the minimum light intensity L of the measured dynamic vision sensor output signal-to-noise ratio equal to 1 stimulated by light intensity change.

5. The method for testing the dynamic range of a dynamic vision sensor according to claim 4, characterized in that, The specific steps of step S3 are as follows: Monochromatic parallel light of known wavelength is emitted as input, and the intensity of this monochromatic parallel light is known and can be set to a relatively strong intensity. The polarizer is adjusted so that the polarization direction of the incident monochromatic parallel light 7 forms a 45-degree angle with the alignment direction of the liquid crystal molecules in the spatial light modulator. The incident monochromatic parallel light passes through the spatial light modulator and analyzer in sequence and finally enters the focal plane of the dynamic vision sensor under test to form a light spot image. Event stream is acquired, and the occurrence frequency f of the average background activity noise of the dynamic vision sensor under test at the current light intensity is calculated. BAH : Where, N ESH t represents the total number of events in this event stream. H For the duration of this event stream, w is the lateral resolution of the focal plane of the dynamic vision sensor under test, and h is the longitudinal resolution of the focal plane of the dynamic vision sensor under test.

6. The method for testing the dynamic range of a dynamic vision sensor according to claim 5, characterized in that, The specific steps of step S4 are as follows: The computer sends control commands to the controller, which then changes the modulation phase of the spatial light modulator according to the commands. By adjusting the grayscale values ​​of the phase map loaded on the spatial light modulator, the output light intensity on the dynamic vision sensor under test is gradually changed. The entire process of event streaming is collected, and the event frequency generated by the light intensity changes under different brightness levels is determined. When this event frequency is 2f... BAH At this time, the change in light intensity is the maximum light intensity L at which the dynamic vision sensor 6, stimulated by the change in light intensity, outputs a signal-to-noise ratio equal to 1. H .

7. The method for testing the dynamic range of a dynamic vision sensor according to claim 6, characterized in that, The specific steps of step S5 are as follows: By changing the light source to different wavelengths, repeat steps S1-S4 to calculate the minimum light intensity L at different wavelengths. LN and maximum light intensity L HN N is 1, 2, 3...M, where M is a positive integer.

8. The method for testing the dynamic range of a dynamic vision sensor according to claim 7, characterized in that, The specific steps of step S6 are as follows: Using the minimum light intensity L at different wavelengths LN and maximum light intensity L HN Calculate the dynamic range of the tested dynamic vision sensor:

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