A method and system for measuring spatial light field of lamps

Abstract

The present invention discloses a method and system for measuring the spatial light field of a lamp. A first imaging measurement device is used to measure the far-field illuminated surface illuminance distribution of the lamp under test within two or more local angle intervals, and synthesizes the global spatial light intensity distribution of the lamp under test. At the same time, a second imaging measurement device is used to measure the luminous surface images of the lamp under test in two or more postures to more accurately obtain the posture information of the lamp when measured by the first imaging measurement device. The global light set information of the lamp under test is calculated using the luminous surface images at various angles, and more spatial light field distribution data is further derived. The lamp spatial light field measurement system includes a rotating stage on which the lamp under test is installed, a diffuse screen, a first imaging measurement device, a second imaging measurement device, and a data transceiver control unit. The first imaging measurement device is aligned with the diffuse screen for measurement, and the second imaging measurement device is aligned with the lamp under test for measurement. Two or more sets of stray light elimination apertures are arranged between the rotating stage and the diffuse screen.

Description

Technical Field

[0001] The present invention relates to the technical field of light radiation measurement, and in particular to a method and system for measuring the spatial light field of a lamp. Background Art

[0002] The spatial light field distribution of a lamp is a key optical property. Currently, a common method in the industry is to measure spatial light intensity distribution using a goniophotometer. This goniophotometer consists of a turntable and an illuminance detector. The illuminance detector measures illuminance at a distance from the lamp being measured and calculates luminous intensity based on the inverse square of the distance. This is referred to as the "scanning method." Another method involves directing the lamp's light beam onto a diffuser screen and using an imaging measurement device to measure the brightness distribution of the light spot reflected from the diffuser screen. The relationship between brightness, illuminance, and luminous intensity is then used to further calculate the light intensity distribution. This method is referred to as the "imaging method."

[0003] Scanning photometric measurement methods offer high accuracy but are slow and struggle to achieve high angular resolution, typically capped at 0.1°. However, some applications (such as determining the light / dark cutoff line for automotive lamps) require resolutions of 0.01° or higher. This is practically impossible with traditional scanning methods due to the size and sensitivity of the detector's receiving surface. Imaging methods offer relatively fast measurement speeds and, provided the imaging measurement device has sufficient pixels and good image quality, can also achieve very high angular resolution. However, imaging methods suffer from lower accuracy. Besides the poor spectral matching and linearity of imaging measurement devices compared to single-channel illuminance detectors, a more significant factor is stray light. When using imaging methods in larger spaces, all light beams from the lamp being measured are projected onto a diffuser screen, resulting in secondary or multiple reflections on the screen. This also generates crosstalk on the sensor surface within the imaging measurement device, all of which are significant sources of stray light. Especially when measuring the dark area of ​​the light beam, it is easily interfered with by the bright area of ​​the light beam. Stray light has become a major problem plaguing the industry. To solve this problem, some proposals have been made to calibrate the stray light algorithm of the imaging measurement device, and some have also proposed to use an illuminance meter to perform scanning measurements in sensitive areas based on the imaging method. However, these methods do not fundamentally solve the problem, and the latter also greatly affects the measurement speed and angular resolution.

[0004] Furthermore, large, multi-module lamps, such as multi-layer navigation lights and matrix and through-type vehicle lights, have become increasingly common in recent years. These lamps either use individual modules as independent evaluation units, measuring the light intensity distribution of each module and determining its compliance, or measure the light intensity distribution of each module separately and then summing them to obtain the light intensity distribution of the entire lamp. When measuring the module light intensity distribution, the photometric center of each module must be aligned with the rotation center of the goniophotometer. This requires the goniophotometer to be sufficiently large and weighted to secure the photometric center of each module in the large lamp to the rotation center. Furthermore, center alignment is difficult to adjust and can easily lead to deviations due to misalignment.

[0005] On the other hand, light distribution measurement needs to be integrated with practical applications. Traditional light intensity distribution measurements are based on the inverse square law of distance. In practical applications, this data is also used to guide lighting design. However, in practice, the distance between the luminaire and the illuminated surface may be relatively close, making the inverse square law difficult to establish. The light intensity distribution of a luminaire cannot fully express the spatial light field information of the luminaire. Summary of the Invention

[0006] To overcome the shortcomings of the existing technology, the present invention provides a method and system for measuring the spatial light field of a lamp, which can achieve high-precision and high-resolution rapid measurement of the full-space light field of a lamp. The specific technical solution is as follows.

[0007] A method for measuring the spatial light field of a lamp measures the far-field illuminance distribution of the illuminated surface of the lamp under test within two or more local angle intervals, and synthesizes the global spatial light field information of the lamp under test. The specific steps are as follows:

[0008] S1: The luminaire under test is mounted on a rotating table. Only a portion of the light beam emitted by the luminaire under test is irradiated onto the diffuser in the far field, while the rest of the light is blocked by the stray light elimination device.

[0009] S2: The first imaging measurement device is aimed at the diffuser screen to measure the illuminance distribution on the diffuser screen; at the same time, the second imaging measurement device is aimed at the lamp under test to obtain an image of the luminous surface of the lamp under test;

[0010] S3: The rotating stage drives the lamp under test to rotate to change the position of the lamp under test, and repeats step S2 to perform measurements in two or more positions;

[0011] S4: Integrate the luminous surface images and the illuminance distribution of the diffuser screen of the tested lamp at different positions to calculate the global spatial light intensity distribution of the tested lamp.

[0012] The present invention uses a first imaging measurement device to measure the illuminance distribution of a measured luminaire within a local angular range. The luminaire is rotated by a rotating stage to measure light distribution in different spatial angular regions, and global spatial light field data is then integrated and calculated. Because the diffuser screen only receives light beams within the local spatial angular range during a measurement, a large number of light beams from non-measured angular regions are blocked by the stray light elimination device. This prevents stray light interference from reflected light on the diffuser screen or within the imaging measurement device, thereby essentially solving the stray light problem inherent in imaging methods. The stray light elimination device includes two or more sets of stray light elimination apertures. The imaging measurement device comprises a two-dimensional array detector, in which each pixel corresponds to a specific location on the diffuser screen, and each location is associated with a spatial coordinate (spatial angle). This means that the local angular range is divided into over one million pixels, resulting in extremely high spatial resolution of the measured data. Compared to conventional single-channel illuminometers that measure illuminance (luminous intensity) through rotational scanning, the present invention requires a much larger scanning step size, resulting in significantly faster measurement speeds and simple and efficient measurements. The second imaging measurement device in the present invention scans and measures the image of the light-emitting surface of the measured lamp, providing richer position information and light information for the integrated calculation of spatial light field data, thereby further improving the reliability of measurement and the integrity of spatial light field data.

[0013] As a supplementary explanation, the principle behind the first imaging measurement device's illuminance distribution measurement is that the diffuser screen is treated as a Lambertian body. The illuminance of a light beam impinging on the diffuser screen is proportional to the brightness produced by its reflection or transmission, and the brightness of the same element in all directions is the same. Therefore, by accurately determining the brightness distribution of the light spot on the diffuser screen, the illuminance distribution impinging on the diffuser screen can be determined. This technical solution also allows the use of a calibration light source to calibrate the first imaging measurement device. If the calibration light source's spatial intensity distribution, distance relative to the diffuser screen, and orientation are known, the illuminance distribution it produces on the diffuser screen can be accurately determined, allowing the first imaging measurement device to be calibrated.

[0014] As a supplementary explanation, the global spatial light field information does not refer to the entire 4π space or infinite plane, but refers to the entire space of interest. For example, when the measurement value of interest is spatial light intensity distribution, many lamps only emit light from the front, so only the 2π angular space to the side of the light-emitting surface is of interest. For the lamp under test, the most basic spatial light field information is the spatial light intensity distribution, which is often expressed as Where, I is the symbol of luminous intensity, It is a directional coordinate with the photometric center of the lamp under test as the origin. The photometric center is sometimes also called the reference center and is represented by the symbol C. According to documents such as CIE 121, the photometric center needs to be determined based on the type of the luminous surface of the lamp under test (for example, transparent or frosted, the shape of the luminous surface, etc.). The light field information can be further extended to include the illuminance distribution of a plane or surface in space, light set data, etc. The illuminance distribution can be expressed as Where E is the illumination symbol, (x, y, z) is the spatial position coordinate, Indicates the normal direction of the surface element. Generally, a reference point on the measured lamp is used as the origin. The reference point can be the center of the luminous surface. The ray set data is represented as Where Φ represents the luminous flux of the light, (x, y, z) represents the coordinates of a point in the light, and a reference point on the lamp being tested is generally used as the origin. is the direction of the light. For the sake of convenience, the photometric center, reference point, and reference center are collectively referred to as the reference center, denoted by C. In specific applications, the coordinate symbols are represented by different subscripts depending on the coordinate system used and the object being represented, as described below.

[0015] As a supplementary explanation, the rotation and / or translation of the lamp under test by the rotating table is achieved through the motion mechanism on the rotating table. The posture of the lamp under test generally includes position and attitude. In the world coordinate system, the posture information of the lamp under test can be expressed as Where (x W,C ,y W,C ,z W,C ) represents the position deviation of the reference center C of the measured lamp relative to the origin of the world coordinate system. Represents the deviation of the measured luminous surface (normal) from a reference direction. The reference direction is generally defined as the center normal of the diffuser. The world coordinate origin, denoted by O, is a fixed point in space, typically the intersection of the two rotation axes of the turntable, or the center of rotation.

[0016] As a technical solution, in step S3, the rotating stage provides the rotation information of the lamp under test; in step S4, the position information of the lamp under test is calculated by combining the rotation information of the lamp under test with the image of the luminous surface, and the position information of the lamp under test corresponding to the illumination distribution in the local angle range of the first imaging measurement device is obtained. In this solution, the rotating stage itself can provide the angle of rotation of the lamp under test relative to the diffuser screen through an encoder, an inclinometer, a gyroscope, etc., which is set as (ε, η), which is important information representing the posture of the lamp under test. In the process of image analysis and calculation of the position information of the lamp under test, the pixels of the second imaging measurement device can be pre-calibrated using an object with clear installation position, angle and size information. Methods for determining the reference center of the lamp under test include but are not limited to methods such as feature point recognition or peripheral feature area recognition; the deflection information of the lamp under test relative to the reference direction can also be achieved by marking feature points on the lamp under test.

[0017] In conventional technology, when the reference center C of the lamp under test coincides with the rotation center O of the turntable, and the normal direction of the luminous surface of the lamp is the same as the reference direction of the turntable (the normal direction of the center of the diffuser screen), the relative rotation angle can be used directly to represent the direction of the luminous intensity. However, when the lamp under test is heavy, angle deviation may occur during the rotation process due to insufficient rigidity of the turntable. At this time, the angle can be verified and corrected in conjunction with the luminous surface image. The luminous surface image obtained by the second imaging measurement device plays a more important role in that when the luminous surface of the lamp under test is relatively complex and it is difficult to determine the reference center C (such as when there are multiple luminous points or the lamp under test has a complex lens) or the lamp is large and the reference center C cannot be coincided with the rotation center O, the luminous surface image at each relative rotation angle can be used to more accurately locate the posture of the lamp under test. For example, when the lamp under test is installed on the turntable, the luminous surface image is used to adjust and determine the initial position of the reference center of the lamp under test and the initial direction of the normal of the luminous surface. The initial posture is recorded as After rotating through a certain angle (ε, η), the position coordinates of the reference center are calculated as shown in formula (1) and the angle of the luminous surface is calculated as shown in formula (2).

[0018]

[0019]

[0020] In this position, the position of the reference center and the angle of the luminous surface are analyzed using the luminous surface image taken by the second imaging measurement device. The pixel coordinates of the second imaging measurement device are calibrated, and the angle between the line connecting a point in space to the second imaging measurement device and the optical axis of the second imaging measurement device is The coordinates of the pixels (i2, j2) of the second imaging measurement device correspond one-to-one. Since the second imaging measurement device is fixed, the actual position of the reference center can be accurately calculated and verified to ensure compliance with expectations. If the actual position observed through the luminous surface image deviates, the reference center and the calculated light intensity distribution must be adjusted and corrected. Furthermore, by scanning and measuring the luminous surface image at various angles, the luminous surface topography of the luminaire under test can be modeled to more precisely determine the position of the reference center C, thereby more accurately obtaining spatial light field information for the luminaire under test.

[0021] As a further limitation of the above technical solution, the system further includes a third imaging measurement device positioned a certain distance from the second imaging measurement device. The third imaging measurement device is aligned with the luminaire under test at another location to obtain an auxiliary image of the luminous surface of the luminaire under test. The system then uses an image recognition algorithm to combine the auxiliary image of the luminous surface with the luminous surface image obtained in step S2 to obtain positional information of the luminaire under test. In this solution, the second and third imaging measurement devices simultaneously obtain images of the luminous surface, and a binocular recognition-based algorithm is used to more accurately determine the positional information of the luminaire under test.

[0022] As a technical solution, in step S4, the following calculation is performed on the illuminance distribution measurement value of the measured lamp in a certain posture: coordinate transformation is performed according to the posture information of the measured lamp, and the spatial angle corresponding to each point on the diffuse screen with the reference center of the measured lamp as the origin is calculated, the distance from each point on the diffuse screen to the reference center of the measured lamp is calculated, and the corresponding luminous intensity value is calculated according to the inverse square relationship of the illuminance distance, so as to obtain the spatial light intensity distribution of the measured lamp corresponding to the posture in the local angle range; the spatial light intensity distribution in the local angle range obtained under each posture is integrated to obtain the global spatial light intensity distribution. Far field space refers to the space far enough away from the lamp under test that the lamp under test can be regarded as a point light source. For example, according to documents such as CIE 121, for a lamp under test with a light pattern similar to a cosine distribution, this distance is at least 5 times the maximum size of the luminous surface. If the lamp under test has a narrow beam angle, the distance is at least 10 times the maximum size of the luminous surface. Beyond this distance, the illuminance measurement of the lamp under test can be converted into a luminous intensity value based on the inverse square relationship of the distance. Figure 1 As shown in Figure 2, it is assumed that the reference center of the luminaire under test is located at the rotation center O of the turntable, and the center normal of the diffusion screen passes through the turntable center O. The distance from the reference center of the luminaire under test to the diffusion screen satisfies the inverse square relationship of the distance. The illuminance of any point on the screen (for example, point A) can be obtained by formula (3):

[0023]

[0024] Where I is the luminous intensity value, d is the distance from the center of the turntable O to the center of the diffuser M, and α is the angle between the line connecting the point A and the center of the turntable O and the center normal, which can be obtained by formula (4). The direction corresponding to point A with the reference center of the measured lamp as the origin. When the (0,0) direction of the measured lamp is set to coincide with the central normal of the diffuser screen, θ = α.

[0025]

[0026] like Figure 2 As shown in Figure 1, when the reference center C of the lamp under test deviates from the turntable center O, the distance from the reference center C to the diffuser screen may change. At this time, a new coordinate position relationship must be established, and the light intensity distribution information with the reference center C as the origin is obtained through coordinate transformation. At this time, the relationship between the illuminance at point A and the luminous intensity is as shown in formula (5).

[0027]

[0028] Where I is the luminous intensity value, α is the angle between the line connecting the point A and the reference center C of the lamp under test and the normal line of the diffuser screen. The reference center is expressed in the world coordinate system with the center of the turntable as the origin as (x W,C ,y W,C ,z W,C ), α can be obtained by formula (6):

[0029]

[0030] where Δx AT' and Δy AT' It is the coordinate difference between the projection C' of the reference center C of the measured lamp on the diffuse screen and point A in the diffuse screen coordinate system.

[0031] The luminous intensity direction corresponding to point A with the reference center of the measured lamp as the origin Through coordinate vector transformation, Direction and attitude of the lamp being tested Calculated.

[0032] As a technical solution, in step S4, the following calculations are performed on the image of the luminous surface of the luminaire under test in a certain position: the luminous surface image is converted into regional ray set information consisting of a number of ray data, including ray direction, position coordinates of a point in the ray, and ray flux; the corresponding regional ray set information at each position is integrated to obtain global ray set information. In this technical solution, the luminous surface image is a luminous surface luminance image or can be converted into a luminous surface luminance image; the luminance image analysis in each direction is used to obtain the ray set information of the luminaire under test in the global space.

[0033] As a further limitation of the above technical solution, the light data corresponds to pixels in the luminous surface image; the light direction is determined based on the posture information of the lamp under test, the posture of the second imaging measurement device, and the pixel coordinates in the second imaging measurement device; the position coordinates of a point in the light are determined by the posture information of the lamp under test and the posture of the second imaging measurement device; the light flux is determined by the pixel response, pixel area and spatial angle.

[0034] Brightness is defined as the luminous flux generated by a unit element on the luminous surface within a unit solid angle, and its expression is shown in formula (7):

[0035]

[0036] in is the light-emitting surface element dA(x s ,y s ,z s ) in the solid angle The luminous flux inside, the surface element position coordinate is (x s ,y s ,z s ), the light direction is

[0037] Based on the response of a pixel in the luminance image obtained by the second imaging measurement device, the corresponding light data can be calculated: the entrance pupil position of the second imaging measurement device corresponds to the position of a point in the light, the light direction is calculated from the posture of the measured luminaire and the pixel coordinates, and the light flux corresponds to the response value of the pixel. The bin size used in the flux calculation is related to the scanning angle interval measured by the second imaging measurement device and corresponds to a bin area on the scanning sphere. The solid angle bin corresponds to the solid angle of the pixel relative to the lens. Due to the reversibility of light, once the light direction and the coordinates of a point in the light are determined, the coordinate position of any other point in the light can be obtained. In actual use, the intersection of the light and the luminous surface of the measured luminaire is often used to represent the light.

[0038] As a further limitation of the above technical solution, in step S4, photometric parameters are derived and calculated based on the global ray set information of the tested luminaire. These photometric parameters include, but are not limited to, illuminance distribution, luminous intensity distribution, total luminous flux, or regional luminous flux for a specified area. In this technical solution, after obtaining the global ray set information, various photometric parameters can be derived. For example, the illuminance value of a specified spatial bin can be obtained by accumulating the ray flux of the ray set that intersects the bin; the luminous intensity value within a specified solid angle bin can be obtained by accumulating the ray flux within that solid angle bin; and the luminous flux can be obtained by accumulating the flux of all rays.

[0039] As a technical solution, it also includes one or more optical radiation probes, which directly receive the light beam from the lamp under test; the optical radiation probes and the first imaging measurement device and the second imaging measurement device are used to measure the same calibration light source or the lamp under test respectively, and the measurement values ​​or calculated values ​​of the first imaging measurement device and / or the second imaging measurement device are calibrated according to the measurement values ​​or calculated values ​​of the optical radiation probes. The above-mentioned optical radiation probes include but are not limited to photometric probes, radiometric probes, spectroradiometers and sampling devices thereof. Generally speaking, the measurement values ​​of a single-channel optical radiation probe have higher measurement accuracy than those of an imaging measurement device, but the disadvantage is that the measurement speed is too slow. Therefore, the measurement values ​​of the optical radiation probe can be used as a supplement in some situations where high precision is required. For example, in the calibration stage, the measurement values ​​or calculated values ​​of the first imaging measurement device and / or the second imaging measurement device are calibrated according to the measurement values ​​of the optical radiation probe using the same calibration light source.

[0040] There are at least two ways to calibrate the first imaging measurement device: one method is to use a calibration light source with a beam angle greater than the angle of the diffuser relative to its rotational center. This means that when the calibration light source is facing the diffuser, the light spot it produces completely covers the diffuser. The known spatial intensity distribution of the calibration light source is then used to calibrate the illuminance at each point on the diffuser. Another method is to use a conventional light intensity standard lamp, where only the luminous intensity along the optical axis is precisely known. The imaging measurement system being calibrated has undergone flat-field calibration before calibration, ensuring consistent illuminance response at all locations. During calibration, the calibration light source is adjusted so that its optical axis is aligned with a specific point on the diffuser. The illuminance response at that point is calibrated, and the illuminance responses at other locations are calibrated proportionally. The former calibration method is relatively simple, while the latter method can achieve luminous intensity values ​​with lower uncertainty, but may be affected by non-cosine errors in the diffuser. For calibration of the second imaging measurement device, the calibration light source should have a uniform luminous surface with a known luminance distribution. In summary, a more convenient calibration method is to use a uniform surface light source with known brightness to produce a light spot on the diffuser screen that is larger than the imaging measurement area. To further improve the measurement accuracy of the imaging measurement device, calibration can be performed using an adjustable calibration light source or multiple calibration light sources. For example, to reduce the linearity error of the imaging measurement device, the calibration light source can be used to generate different levels of illumination distribution and / or surface brightness distribution. To reduce the spectral mismatch error of the imaging measurement device, the calibration light source can be used to generate different spectral output beams.

[0041] As a further limitation of the above technical solution, in step S4, the photometric parameters derived and calculated using the global light set information are compared with the measurement values ​​of the first imaging measurement device, and the global light set information is corrected based on the comparison results. While the two devices actually verify each other, the derivation and calculation process of the second imaging measurement device is more complex, and the absolute brightness values ​​obtained when measuring directly against the object being measured may deviate. Therefore, using the measurement values ​​of the first imaging measurement device to correct the derived values ​​of the second imaging measurement device can improve measurement accuracy.

[0042] As a technical solution, a fast photometer is used to measure the change in illuminance over time, and the light modulation period is further calculated. The measurement integration time of the first imaging measurement device and / or the second imaging measurement device is an integer multiple of the modulation light period. When the light beam emitted by the lamp under test has a modulation characteristic, the integration time of the imaging measurement device must be an integer multiple of the modulation period, otherwise there will be greater instability. Measuring the light modulation period by a fast photometer can help the imaging measurement device select a suitable integration time. It is worth mentioning that there may be multiple light sources in the lamp under test, and the modulation periods of light sources emitting in different directions will be different. In this case, the modulated light period in each angular area can be first obtained by a fast photometer, and when the light beam in the corresponding area is scanned onto the diffuse screen, the integration time is used for measurement.

[0043] As a technical solution, the first imaging measurement device has a colorimetric measurement function. During the measurement in steps S2 and S3, the color distribution of each point on the diffuser screen is output. In step S4, the color distribution parameters are calculated to determine how they vary with spatial angle. The color distribution parameters complement the photometric parameters, providing richer measurement data.

[0044] As a technical solution, a bidirectional scattering distribution function (or bidirectional reflection distribution function or bidirectional transmission distribution function) of the diffusion screen is obtained, and the bidirectional scattering distribution function is used to correct the local area illumination distribution obtained by the first imaging measurement device.

[0045] The premise of using the imaging method is that the diffuser screen is a uniform cosine screen, that is, the illuminance of light in any irradiation direction can produce equal brightness in all directions. At this time, the illuminance E and the brightness L at a certain point on the diffuser screen are proportional, that is, E = (L·π) / ρ, where ρ is the reflectance. However, in actual measurements, when the incident angle of light is relatively large or the brightness measurement angle is large, the cosine characteristics of the diffuser screen are difficult to guarantee, which will cause significant errors. In order to reduce or avoid the influence of the non-cosine reflection / transmission of the diffuser screen, the bidirectional reflection / transmission distribution function of the diffuser screen can be measured and used to correct the luminous intensity value of the lamp under test in step S4. Figure 3 As shown, the bidirectional reflection / transmission distribution function ρ(ω i ,ω s) refers to the distribution of reflectance or transmittance with angle when incident on the diffuser from different directions, as shown in formula (8).

[0046] ρ(ω i ,ω s )=dL s (ω s ) / dE i (ω i )…………………………………………(8)

[0047] Where ω i is the incident light direction, specifically Figure 3 in Indicates the zenith angle and azimuth angle of the incident light direction; ω s is the direction of scattered light, specifically Figure 3 in Indicates the zenith angle and azimuth of the scattered light direction; dL s (ω s ) means in Differential brightness in the direction of scattered light, dE i (ω i ) means in The differential illuminance on the diffuser surface in the direction of incident light.

[0048] Using formula (8), the imaging measurement device can obtain the illuminance value of each position on the diffuse screen, as shown in formula (9):

[0049]

[0050] Where (x, y) is the coordinate of a point on the diffuse screen, E(x, y) is the illumination at the (x, y) position, and L(x, y) is the brightness at the (x, y) position. After the point is determined, the corresponding incident light direction ω i ,Right now can be uniquely determined; according to the measurement arrangement, the direction ω of the point incident on the imaging measurement device s ,Right now It can also be determined.

[0051] As a technical solution, during the measurement process in step S3, a preliminary analysis is performed based on the illuminance distribution on the diffuser screen captured by the imaging measurement device. If the illuminance distribution fluctuates dramatically, the rotating stage is controlled so that the bright and dark areas of the light beam emitted by the measured lamp are separately illuminated on the diffuser screen for measurement. This technical solution implements image recognition and analysis during the scanning measurement process to separate the measurement of the dark area and the brightness, thereby reducing the risk of secondary reflection of brightness light entering the dark area during measurement, which can cause stray light errors in the dark area.

[0052] As a technical solution, during the scanning measurement process of step S3, there is an overlapping area between the two measurements of the first imaging measuring device. In step S4, the illumination distribution data of the overlapping area is analyzed, the error factors are analyzed and the data is corrected. The error factors include but are not limited to stray light, light blocking or angle accuracy.

[0053] As a technical solution, the angular resolution of each area within the field of view of the first imaging measurement device and / or the second imaging measurement device is measured, and the pixel measurement values ​​are merged according to the angular resolution threshold. The angular resolution that can be achieved when measuring using the method described in the present invention is not equivalent to the pixels of the imaging measurement device, but is more related to the angular resolution of the entire optical system. High pixels do not mean high resolution, but on the contrary, it will increase useless information and take up a lot of memory. An angular resolution chart is set on the surface of the diffuse screen, and an imaging measurement device is used to obtain an image, and the minimum resolvable line pair lp / mm is analyzed. The line pair is used to obtain the angular resolution of the imaging measurement device in each area of ​​the diffuse screen through trigonometric functions (the center and the periphery may be different). In the actual illuminance distribution obtained, the pixel responses within the resolvable angle range are merged and calculated in combination with the angular resolution. The illuminance is represented by the average value of the pixels in the range, and the angle can be selected using the center value.

[0054] Based on the above-mentioned measurement method, the present invention provides a spatial light field measurement system for lamps, comprising a rotating table for mounting the lamp to be measured, a diffuse screen arranged opposite the rotating table, a first imaging measurement device, a second imaging measurement device, and a data transceiver control unit; the first imaging measurement device is aligned with the diffuse screen and measures, and the second imaging measurement device is aligned with the lamp to be measured; the rotating table has a motion mechanism that drives the lamp to be measured to rotate; two or more sets of stray light elimination apertures are arranged between the rotating table and the diffuse screen; the first imaging measurement device, the second imaging measurement device, and the motion mechanism are all communicatively connected to the data transceiver control unit.

[0055] The first imaging measurement device in the present invention comprises a two-dimensional array detector for measuring the illuminance distribution of the light spot projected by the measured lamp onto the diffuser screen. Each pixel of the array detector corresponds to a specified position point on the diffuser screen, and each position point corresponds to a spatial angle. A rotating stage drives the measured lamp to rotate and / or translate, thereby enabling light measurement in different spatial regions. The second imaging measurement device provides more detailed and accurate position information for the first imaging device. Because only the illuminance distribution within a local angular range is measured, the incident angle on the diffuser screen is significantly reduced, significantly minimizing errors caused by the non-cosine characteristics of the diffuser screen. The relatively small screen area also significantly reduces stray light interference caused by secondary reflections, thereby significantly improving measurement accuracy.

[0056] As a further limitation and improvement of the above technical solution, the light aperture of the stray light elimination aperture is slightly larger than the cross-section of the light beam at its position, or in other words, the light aperture of the stray light elimination aperture is slightly larger than the angle of the line connecting the outer side of the maximum measurable luminous surface and the edge of the measurement area of ​​the diffuse screen.

[0057] As a technical solution, the above-mentioned diffuse screen is a diffuse reflection screen, and the imaging measurement device is set on the side close to the lamp under test; or the above-mentioned diffuse screen is a diffuse transmission screen, and the imaging measurement device is set on the side away from the lamp under test. When the diffuse screen is a diffuse reflection screen, the first imaging measurement device can be set near the lamp under test, and no additional measurement space is required. When the diffuse screen is a diffuse transmission screen, the imaging measurement device is preferably set on the other side of the diffuse transmission screen and aligned with the diffuse transmission screen, away from the lamp under test; the light beam emitted by the lamp under test is projected onto the screen to form an image, and its transmitted light diffuses to the other side and is then received by the imaging measurement device. This technical solution can avoid distortion errors caused by the imaging measurement device being tilted to avoid blocking the light emitted by the lamp under test. During measurement, a suitable diffuse screen can be selected based on actual measurement needs.

[0058] As a technical solution, a light-shielding tunnel is provided between the turntable and the diffuser screen, with a stray light diaphragm located within the light-shielding tunnel. The light-shielding tunnel further eliminates stray light interference. Furthermore, the enveloping light-shielding tunnel reduces the total measurement space, leaving the area outside the light-shielding tunnel free for other uses.

[0059] As a technical solution, the distance between the diffusion screen and the rotating stage can be moved or the diffusion screen includes two or more diffusion screens that can be cut in and out.

[0060] As a technical solution, it includes one or more optical radiation probes that directly receive the light beam emitted by the lamp under test. The optical radiation probes include but are not limited to: illuminance probes, radiometry probes, fast photometry detectors and / or spectroradiometers and their sampling devices; the optical radiation probes are communicatively connected to the data transceiver control unit.

[0061] As a technical solution, an alignment laser is used to create a characteristic line on a diffuser screen for aligning the luminaire under test. Specifically, the alignment laser can be positioned on a rotating table at the central axis of the luminaire under test and removed during measurement. Alternatively, the alignment laser can emit two mutually perpendicular laser beams, with the plane formed by these beams parallel to the diffuser screen, and the line connecting the reference center of the luminaire under test and the intersection of the two intersecting laser beams is perpendicular to the diffuser screen.

[0062] As a technical solution, a calibration light source with stable light output is built into the turntable. Calibration of the luminaire spatial light field measurement system using a calibration light source with known luminous intensity and / or brightness further ensures measurement accuracy. Furthermore, the luminous intensity and / or correlated color temperature of the calibration light source are adjustable.

[0063] Beneficial effects of the present invention: The present invention provides a method and system for measuring the spatial light field of lamps, which measures the illuminance distribution of the illuminated surface in each local angle interval and the image of the luminous surface at each angle, and analyzes and calculates the complete spatial light field information of the measured lamp. Since only the illuminance distribution of the local area is measured, the stray light interference caused by secondary reflection can be greatly reduced, thereby greatly improving the measurement accuracy of the luminous intensity. At the same time, combined with the measurement of the image of the luminous surface at each angle, the illuminance distribution on any illuminated surface can be further analyzed, thereby realizing accurate, fast and complete measurement of the spatial light field of the lamp. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Attachment Figure 1 Schematic diagram of the principle of illumination distribution measurement of the present invention;

[0065] Attachment Figure 2 Schematic diagram of another principle of illumination distribution measurement of the present invention;

[0066] Attachment Figure 3 Schematic diagram of the measurement principle of calculating illumination using bidirectional reflection / transmission distribution function of the present invention;

[0067] Attachment Figure 4 A schematic diagram of the overall structure of a lamp spatial light field measurement system provided in the first embodiment of the present invention;

[0068] Attachment Figure 5 A side view of a lamp spatial light field measurement system provided in the first embodiment of the present invention;

[0069] Attachment Figure 6 A schematic diagram of the overall structure of a lamp spatial light field measurement system provided in the second embodiment of the present invention;

[0070] Attachment Figure 7 This is a side view of a lamp spatial light field measurement system provided in the second embodiment of the present invention.

[0071] In the figure, 1- lamp under test, 2- rotating table, 3- diffusion screen, 4- first imaging measurement device, 5- second imaging measurement device, 6- stray light elimination aperture, 7- third imaging measurement device, 8- alignment laser, 9- light shielding tunnel, 10- light radiation probe, 10-1- photometric probe, 10-2- spectrometer receiver. DETAILED DESCRIPTION

[0072] Example 1:

[0073] This embodiment provides a system for measuring the spatial light field of a lamp, the structural diagram of which is shown in FIG. Figure 4 and Figure 5 As shown, the system includes a rotating stage 2 on which the luminaire under test 1 is mounted, a diffuser screen 3 positioned opposite the rotating stage 2 at an inverse square distance, a first imaging measurement device 4, a second imaging measurement device 5, a third imaging measurement device 7, a photometer probe 10-1, and a spectrometer receiver 10-2. The system also includes a data transceiver control unit, an alignment laser 8, and a calibration light source built into the rotating stage. The rotating stage 2, the first imaging measurement device 4, the second imaging measurement device 5, the third imaging measurement device 7, the photometer probe 10-1, and the spectrometer receiver 10-2 are all communicatively connected to the data transceiver control unit. The calibration light source is positioned on the rotating stage 2, with its light outlet aligned with the diffuser screen 3, for calibrating the luminaire spatial light field measurement system. In this embodiment, the diffuser screen 3 is a diffuse reflection screen. The first imaging measurement device 4 is positioned in the space between the diffuser screen 3 and the rotating stage 2, aligned with the diffuser screen 3, to measure the illuminance distribution of the light spot projected onto the diffuser screen 3 by the luminaire under test, thereby obtaining the light intensity distribution within a local spatial angular interval. The rotating stage 2 rotates the luminaire under test 1 around its horizontal and vertical axes, switching between different angles for incident light onto the diffuser screen 3. Three stray light suppression apertures 6 are provided between the rotating stage 2 and the diffuser screen 3. The apertures of these apertures are slightly larger than the angle between the edge of the maximum measurable luminous surface and the edge of the measurement area of ​​the diffuser screen 3.

[0074] In this system, the horizontal rotation axis of the rotating stage 2 coincides with the center normal of the diffuser screen, and the distance between the rotation center of the rotating stage 2 and the center of the diffuser screen is known. The first imaging measurement device 4, the second imaging measurement device 5, and the third imaging measurement device 7 always remain stationary, and their spatial coordinates relative to the rotation center of the rotating stage are known. The alignment laser 8 generates a cross laser, the center of which is aligned with the center of the diffuser screen. With the help of the alignment laser, the first imaging measurement device 4 is aligned with the diffuser screen, and the coordinates of each pixel (i1, j1) of the first imaging measurement device 4 are aligned with the coordinates of each point on the diffuser screen (x M ,y M ) are calibrated one by one, and the angle between the direction of light collected by each pixel and the normal direction of the diffuser screen is The deviation between the pixel position and the optical axis of the first imaging measurement device 4 is accurately calculated. The optical axes of the second and third imaging measurement devices 5 and 7 are aligned with the rotation center of the rotating stage, and each pixel of the second imaging measurement device 5 is calibrated using brightness response.

[0075] The specific method and steps for measuring spatial light field distribution using the above system are as follows:

[0076] A1: Use a calibration light source to calibrate the first imaging measurement device. The light spot of the calibration light source covers the measurement area on the diffuser screen. The illumination distribution on the diffuser screen is known and can be verified by a photometric probe set on one side of the diffuser screen.

[0077] A2: Mount the lamp under test on a rotating stage. The lamp under test is a through-type headlight with two headlamps integrally mounted on a single mechanical component. Illuminate the diffuser with an aiming laser. Simultaneously illuminate one headlamp. Adjust the rotating stage so that the cutoff line of the headlamp's light spot aligns with the laser to determine the (0,0) orientation of the headlamp. Normally, the headlamp's reference center C should coincide with the rotation center O. However, due to the limited translational space of the rotating stage, the reference center C is separated from the rotation center O by a distance. A second imaging measurement device is used to determine the distance between C and O. Simultaneously, the aiming laser is used again to adjust the headlamp's angle so that the (0,0) orientation of the headlamp corresponds to point C', the projection of the reference center C on the diffuser.

[0078] A3: Measurement sampling begins. The light beam from the luminaire under test within a local angular range is irradiated onto the diffuser screen, while the remaining light is blocked by the stray light suppression aperture. The first imaging measurement device is aligned with the diffuser screen to measure the illuminance distribution of the diffuser screen. Simultaneously, the second imaging measurement device is aligned with the luminaire under test to obtain a brightness image of the luminous surface of the luminaire under test. The rotating stage rotates the luminaire under test to change its position. The angular interval of measurement sampling is no greater than the angular span of the diffuser screen relative to the rotation center, and the angular range of measurement sampling covers the luminous space of the luminaire under test of interest. During the specific rotational measurement process, preliminary image recognition and analysis are performed based on the illuminance distribution on the diffuser screen 3 captured by the first imaging measurement device 4. If the obtained illuminance distribution shows drastic changes in brightness and darkness, the turntable is controlled to rotate so that the bright and dark areas are illuminated on the diffuser screen and measured as separately as possible. When sampling with the first imaging measurement device 4 and the second imaging measurement device 5, an integer multiple of the luminaire modulation period is selected as the sampling integration time, with reference to the rapid illuminance changes obtained by the photometer probe 10-1.

[0079] A4: Integrate the luminous surface images and the illuminance distribution of the diffuser of the luminaire under test at different positions to calculate the global spatial light intensity distribution of the luminaire under test.

[0080] In step A4, since the illuminance of the first imaging measurement device has been calibrated by the calibration light source, the illuminance distribution of each point on the diffuser screen can be directly obtained. However, since the reference center C of the lamp under test is separated from the rotation center O of the turntable by a certain distance, the position of the reference center changes by (x W,C ,y W,C ,z W,C), and since the initial angle direction of the measured lamp is parallel to the central axis of the system, the angle of the measured lamp in the world coordinate system is consistent with the rotation angle of the turntable, which is (ε,η). The position coordinates of the reference center C are calculated as follows:

[0081]

[0082] The illuminance distribution on the diffuser screen is converted into the light intensity distribution with the reference center C as the origin by the following formula:

[0083]

[0084] in is the direction corresponding to any point A on the diffuse screen with the reference center as the origin, through (ε,η) and It is obtained by summing the vectors of the directions. The position of point A is calculated by (α, β), and α and β can be obtained by the following formula:

[0085]

[0086]

[0087] where Δx AC' and Δy AC‘ are the coordinate differences of point A and point C' respectively.

[0088] A4: Integrate the luminous surface images and the illuminance distribution of the diffuser of the luminaire under test at different positions to calculate the global spatial light intensity distribution of the luminaire under test.

[0089] A5: Based on the brightness images in all directions measured by the second imaging measurement device, the global light set information of the measured lamp is further derived. The specific method is as follows:

[0090] Taking the reference center of the lamp under test as the origin, the coordinates of the point through which the light data corresponding to any pixel P in the second imaging measurement device passes are (x C,2 ,y C,2 ,z C,2 ), the light direction is expressed as The light flux is expressed as dΦ C,P .

[0091] The specific calculation formula is as follows:

[0092]

[0093]

[0094] y C,2 =d2·cos(θ W,2+ε)-z W,C

[0095] The direction of the light is obtained by adding the direction of the pixel coordinate relative to the exit pupil and the direction vector of the second imaging measurement device relative to the rotation center, and then transforming it to the coordinate system with the reference center C of the measured lamp as the origin through the left side.

[0096] The formula for calculating light flux is:

[0097] dΦ C,P =L(i 2,P ,j 2,P )·dA(x W,2 ,y W,2 ,z W,2 )·dΩ(i 2,P ,j 2,P )

[0098] Among them, (i 2,P ,j 2,P ) is the pixel coordinate corresponding to point P, dA(x W,2 ,y W,2 ,z W,2 ) is the area of ​​the corresponding surface element at this angle, which is related to the rotation interval of the rotating stage, dA(x W,2 ,y W,2 ,z W,2 ) is the solid angle element corresponding to the pixel point, which is calculated by the pixel size and position.

[0099] In this embodiment, in order to obtain global light set information more accurately, the sampling angle interval of the second imaging measurement device can be reduced. In the case of limited measurement sampling, richer information can be obtained through brightness image interpolation.

[0100] A6: After obtaining the global light data, other photometric parameters can be further derived and calculated. For example, the luminous intensity corresponding to any point A on the diffuser screen and the illuminance value of a certain surface element can be calculated using the following formulas:

[0101]

[0102] Intersects ΔA within the surface element

[0103] is the solid angle element of the light intensity direction corresponding to point A on the diffuse screen.

[0104] The same method can also be used to derive the luminous intensity and illumination corresponding to the location of the photometer probe. Therefore, the photometric value measured by the first imaging measurement device or the photometer probe can be used to calibrate or verify the measurement value of the second imaging measurement device.

[0105] Example 2:

[0106] This embodiment provides another system for measuring the spatial light field of a lamp. The structural diagram is shown in FIG. Figure 6 and Figure 7 As shown, the system includes a rotating stage 2 on which a lamp under test 1 is mounted, a diffuser screen 3 located opposite the rotating stage 2 at an inverse square distance, a first imaging measurement device 4, a second imaging measurement device 5, a light radiation probe 10, an alignment laser 8, and a data transceiver control unit. The diffuser screen 3 is a diffuse transmission screen. The first imaging measurement device 4 is located outside the diffuser screen 3, away from the rotating stage 2, and aligned with the diffuser screen 3. It measures the light spot information on the diffuser screen 3 within a certain angle range to obtain the illuminance distribution. The rotating stage 2, the first imaging measurement device 4, the second imaging measurement device 5, and the light radiation probe 10 are all communicatively connected to the data transceiver control unit. The rotating stage 2 rotates the lamp under test 1, switching between different angle regions for incident light on the diffuser screen 3. The rotating stage 2 can move up and down, left and right, and forward and backward to align the reference center C of the lamp under test with the rotation center O of the rotating stage 2. Three removable stray light suppression apertures 6 are positioned between the turntable 2 and the diffuser screen 3. Their apertures are slightly larger than the angle between the edge of the maximum measurable luminous surface and the edge of the measurement area on the diffuser screen 3. An alignment laser 8 emits two perpendicular laser beams, with their intersection located at the center of the diffuser screen 3. The system includes a light-shielding tunnel 9, within which the stray light suppression apertures 6, diffuser screen 3, first imaging measurement device 4, and second imaging measurement device 5 are located. This further minimizes stray light interference and improves laboratory space utilization.

[0107] In this system, the horizontal rotation axis of the rotating stage 2 coincides with the center normal of the diffuser screen, and the distance between the rotation center of the rotating stage 2 and the center of the diffuser screen is known. The first imaging measurement device 4 and the second imaging measurement device 5 always remain fixed, and their spatial coordinates relative to the center of the rotating stage are known. With the help of the alignment laser, the first imaging measurement device 4 is aligned with the diffuser screen, and the coordinates of each pixel (i1, j1) of the first imaging measurement device 4 are aligned with the coordinates of each point on the diffuser screen (x M ,y M ) are calibrated one by one, and the angle between the direction of light collected by each pixel and the normal direction of the diffuser screen is The deviation of the pixel position from the optical axis has also been accurately calculated based on the tilt angle of the first imaging measurement device 4 and the deviation of the pixel position from the optical axis. The optical axis of the second imaging measurement device 5 is aligned with the rotation center of the rotating stage 2, and each pixel of the second imaging measurement device 5 is calibrated by the brightness response.

[0108] The specific method and steps for measuring spatial light field distribution using the above system are as follows:

[0109] B1: Install the luminaire under test on a rotating stage and adjust the stage so that the reference center C of the luminaire under test coincides with the rotation center O. During the adjustment process, rotate the stage and observe the position of the reference center C in the luminance image acquired by the second imaging measurement device 5 to ensure that the luminaire reference center C is always located at the center of the luminance image. At the same time, with the assistance of an alignment laser, observe the light spot on the diffuser screen to ensure that the (0,0) direction of the luminaire under test coincides with the system optical axis, i.e., the center normal direction of the diffuser screen.

[0110] B2: Measurement sampling begins. The light beam from the luminaire under test within a local angular range is irradiated onto the diffuse transmission screen 3, while the remaining light is blocked by the light-shielding tunnel and stray light aperture. The first imaging measurement device 4 is aimed at the diffuse transmission screen 3 to measure the illuminance distribution of the diffuse transmission screen. Simultaneously, the second imaging measurement device 5 is aimed at the luminaire under test 1 to obtain a luminance image of the luminous surface of the luminaire under test 1. The rotating stage 2 rotates the luminaire under test 1 to change its position. The angular interval of measurement sampling is no greater than the angle of the diffuse transmission screen relative to the rotation center, and the angular range of measurement sampling covers the luminous space of the luminaire under test. During the specific rotational measurement process, preliminary image recognition and analysis are performed based on the illuminance distribution on the diffuse transmission screen 3 captured by the first imaging measurement device 4. If the obtained illuminance distribution shows drastic changes in brightness and darkness, the turntable is controlled to rotate so that the bright and dark areas are illuminated on the diffuse transmission screen and measured as separately as possible. When sampling with the first and second imaging measurement devices 4 and 5, an integer multiple of the luminaire modulation period is selected as the sampling integration time, referring to the rapid illuminance changes obtained by the optical radiation probe 10.

[0111] B3: Integrate the luminous surface images and the illuminance distribution of the diffuser of the tested luminaire at different positions to calculate the global spatial light intensity distribution of the tested luminaire.

[0112] In step B3, (x M ,y M ) is the coordinate of a point on the diffuse screen, and the corresponding incident light direction ω i Zenith angle and azimuth According to the coordinate point (x M ,y M ) and the distance d between the center of the lamp under test and the diffuser M Calculated, that is The corresponding scattered light direction ω s Zenith angle and azimuth It has been calibrated by pixel coordinates and can actually be calculated using the following method: Where s is the distance from the diffuser screen to the entrance pupil of the first imaging measurement device; according to the formula Calculate the illuminance value produced by the tested lamp on the diffuser 3, where ρ(ω i ,ωs ) is the bidirectional scattering function of the diffuse screen. According to the formula I(x M ,y M )=E(x M ,y M )·d M 2 / cos 3 ɑCalculate the light intensity distribution corresponding to each point, where ɑ is the position point (x M ,y M ) and the center of the turntable and the angle between the central axis of the system. M ,y M ) is related to the incident angle. When the rotation angle of the rotating stage is (ε,η), (x M ,y M ) corresponds to the spatial angle (ε+ɑ,η+β), where

[0113] B4: Calculate the global light set information of the measured lamp based on the brightness images at various angles obtained by the second imaging measurement device. The calculation method is similar to that of the first embodiment. However, since the reference center of the measured lamp is located at the rotation center, the calculation process is relatively simple.

[0114] B5: Calculate more spatial photometric distributions of interest using the global ray set data, including the illuminance value at the light radiation probe 10, and use the measurement value of the light radiation probe to correct the absolute value of the ray set data; calculate the illuminance distribution of the diffuser screen at a certain rotation angle using the global ray set data, and verify the relative value by comparing it with the measurement value of the first imaging measurement device to ensure the accuracy of the global ray set data.

[0115] Preferably, the angular resolution of each area of ​​the field of view of the first imaging measurement device and the second imaging measurement device at the working distance is measured, and the measured values ​​within the angular resolution range of each area are merged and averaged in steps B3 and B4. The angular resolution that can be achieved when measuring using the method described in this embodiment is not equivalent to the pixels of the imaging measurement device, but is more related to the angular resolution of the entire optical system. High pixels do not mean high resolution, but will increase useless information and take up a large amount of memory. An angular resolution chart is set on the surface of the diffuse screen, and an imaging measurement device is used to obtain an image, and the minimum resolvable line pair lp / mm is analyzed. The line pair is used to obtain the angular resolution of the imaging measurement device in each area of ​​the diffuse screen through trigonometric functions (the center and the periphery may be different). In the actual illuminance distribution obtained, the pixel responses within the resolvable angle range are combined and calculated in combination with the angular resolution. The illuminance is represented by the average value of the pixels in the range, and the angle can be expressed by the center value.

[0116] While the specific embodiments of the present invention have been described above with reference to the accompanying drawings, it should be understood by those skilled in the art that the above embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. It should be understood by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for measuring the spatial light field of a lamp, characterized in that: Measure the far-field illuminance distribution of the illuminated surface of the luminaire under test in two or more local angle intervals, and synthesize the global spatial light field information of the luminaire under test. The specific steps are as follows: S1: The luminaire under test is mounted on a rotating table. Only a portion of the light beam emitted by the luminaire under test is irradiated onto the diffuser in the far field, while the rest of the light is blocked by the stray light elimination device. S2: The first imaging measurement device is aimed at the diffuser screen to measure the illuminance distribution of the diffuser screen; at the same time, the second imaging measurement device is aimed at the lamp under test to obtain an image of the luminous surface of the lamp under test; S3: The rotating stage drives the lamp under test to rotate to change the position of the lamp under test, and repeats step S2 to perform measurements in two or more positions; S4: Integrate the luminous surface images and the illuminance distribution of the diffuser screen of the tested lamp at different positions to calculate the global spatial light intensity distribution of the tested lamp.

2. The method for measuring the spatial light field of a lamp according to claim 1, wherein: The rotating stage described in step S3 provides rotation information of the lamp under test; in step S4, the rotation information of the lamp under test and the image of the luminous surface are combined to calculate the posture information of the lamp under test, and the posture information of the lamp under test corresponding to the illumination distribution measured by the first imaging measurement device in the local angle interval is obtained.

3. The method for measuring the spatial light field of a lamp according to claim 1 or 2, characterized in that: In step S4, the following calculation is performed on the illuminance distribution measurement value of the measured lamp in a certain posture: coordinate transformation is performed according to the posture information of the measured lamp, and the spatial angle corresponding to each point on the diffuse screen with the luminous center of the measured lamp as the origin is calculated, and the distance from each point on the diffuse screen to the luminous center of the measured lamp is calculated and the corresponding luminous intensity value is calculated according to the inverse square relationship of the illuminance distance, so as to obtain the spatial light intensity distribution of the measured lamp corresponding to the posture in the local angle range; the spatial light intensity distribution in the local angle range obtained in each posture is integrated to obtain the global spatial light intensity distribution.

4. The method for measuring the spatial light field of a lamp according to claim 1 or 2, characterized in that: In step S4, the following calculations are performed on the luminous surface image of the lamp under test in a certain posture: the luminous surface image is converted into regional light set information composed of a number of light data, wherein the light data includes the light direction, the position coordinates of a point in the light and the light flux; the regional light set information corresponding to each posture is integrated to obtain the global light set information.

5. The method for measuring the spatial light field of a lamp according to claim 4, characterized in that: The light data corresponds to the pixels in the luminous surface image; the light direction is determined based on the posture information of the lamp under test, the posture of the second imaging measurement device, and the pixel coordinates in the second imaging measurement device; the position coordinates of a point in the light are determined by the posture information of the lamp under test and the posture of the second imaging measurement device; the light flux is determined by the pixel response, pixel area, and spatial angle.

6. The method for measuring the spatial light field of a lamp according to claim 4, wherein: In step S4, photometric parameters are derived and calculated based on the global light set information of the tested lamp. The photometric parameters include but are not limited to the illuminance distribution of a specified surface, the spatial light intensity distribution, the total luminous flux or the regional luminous flux.

7. The method for measuring the spatial light field of a lamp according to claim 6, wherein: In step S4, the measurement value obtained by the first imaging measurement device is compared with the photometric parameters calculated by deriving the global light set information, and the global light set information is corrected according to the comparison result.

8. The method for measuring the spatial light field of a lamp according to any one of claims 1 to 7, wherein: The system further includes one or more optical radiation probes, which receive a light beam from the lamp under test; the optical radiation probes and the first imaging measurement device and the second imaging measurement device are used to respectively measure the same calibration light source or the lamp under test; and the measurement values ​​or calculated values ​​of the first imaging measurement device and / or the second imaging measurement device are calibrated based on the measurement values ​​or calculated values ​​of the optical radiation probes.

9. The method for measuring the spatial light field of a lamp according to any one of claims 1 to 8, wherein: A fast photometer is used to measure the change of illumination over time, and the light modulation period is further calculated. The measurement integration time of the first imaging measurement device and / or the second imaging measurement device is an integer multiple of the modulation light period.

10. The method for measuring the spatial light field of a lamp according to any one of claims 1 to 9, characterized in that: The first imaging measurement device has a chromaticity measurement function, outputs the chromaticity distribution of each point on the diffusion screen in the measurement of steps S2 and S3, and calculates the change of chromaticity parameters with spatial angle in step S4.

11. The method for measuring the spatial light field of a lamp according to any one of claims 1 to 10, characterized in that: A bidirectional scattering distribution function of the diffusion screen is obtained, and the bidirectional scattering distribution function is used to correct the diffuse illumination distribution obtained by the first imaging measurement device.

12. The method for measuring the spatial light field of a lamp according to any one of claims 1 to 10, characterized in that: It also includes a third imaging measurement device set at a certain distance from the second imaging measurement device, and the third imaging measurement device is aimed at the lamp under test at another position to obtain an auxiliary image of the light-emitting surface of the lamp under test; the auxiliary image of the light-emitting surface is used to further identify and analyze the posture information of the lamp under test.

13. The method for measuring the spatial light field of a lamp according to any one of claims 1 to 12, characterized in that: During the scanning measurement process of step S3, there is an overlapping area between the two measurements of the first imaging measurement device. In step S4, the illumination distribution data of the overlapping area is analyzed, the error factors are analyzed and the data is corrected. The error factors include but are not limited to stray light, light blocking or angle accuracy.

14. A lamp spatial light field measurement system based on the lamp spatial light field measurement method according to claim 1, characterized in that: The invention comprises a rotating table (2) for mounting a lamp to be measured (1), a diffusion screen (3) arranged opposite to the rotating table (2), a first imaging measurement device (4), a second imaging measurement device (5) and a data transceiver control unit; the first imaging measurement device (4) is aligned with the diffusion screen (3) and measures, and the second imaging measurement device (5) is aligned with the lamp to be measured (1); two or more groups of stray light elimination apertures (6) are arranged between the rotating table (2) and the diffusion screen (3); the first imaging measurement device (4), the second imaging measurement device (5) and the rotating table (2) are all communicatively connected to the data transceiver control unit.

15. The lamp spatial light field measurement system according to claim 14, characterized in that: The diffusion screen (3) is a diffuse reflection screen, and the imaging measurement device is arranged between the diffusion screen and the lamp to be measured; or the diffusion screen is a diffuse transmission screen, and the imaging measurement device is arranged outside the diffusion screen on a side away from the lamp to be measured.

16. The lamp spatial light field measurement system according to claim 14, characterized in that: It comprises a light-shielding tunnel (9), wherein the light-shielding tunnel (9) is arranged between the rotating platform and the diffusion screen, and the stray light elimination aperture (6) is arranged in the light-shielding tunnel.

17. The lamp spatial light field measurement system according to claim 14, characterized in that: The invention comprises one or more light radiation probes (10) for receiving a light beam of a lamp (1) to be tested, wherein the light radiation probes include but are not limited to: an illuminance probe, a radiometry probe, a fast photometric detector and / or a spectroradiometer and a sampling device thereof; the light radiation probes are communicatively connected to a data transceiver control unit.

18. The lamp spatial light field measurement system according to claim 14, characterized in that: The rotating stage has a built-in calibration light source with stable light output.

Images