Device and method for measuring near-field optical expansion amount of LED (light-emitting diode)

Abstract

The invention relates to the field of LED optical measurement, in particular to an LED near-field optical expansion measuring device and method. The LED near-field optical expansion measuring device comprises a light source module, a first variable lens, a second variable lens, an optical power sensor and a main control computer, wherein a first variable diaphragm is arranged on one side, close to the light source module, of the first variable lens; and a second variable diaphragm is arranged on one side, close to the first variable lens, of the second variable lens. Based on an accurate LED light source near-field model, after the near-field model of the LED light source is obtained through measurement of a small light source testing system SIC-400, measurement of the optical expansion amount can be achieved only by tracing light data in the near-field model, and the method has the advantages of being good in repeatability, convenient and rapid; by adjusting the optical expansion amount measurement method of the diaphragms in front of the two lenses, the application requirement of an optical system with rotational symmetry can be met, and the near-field expansion amount measurement of most LED light sources can be met.

Description

Technical Field

[0001] The present invention relates to the field of LED optical measurement, and in particular to a device and method for measuring near-field optical etendue of LED. Background Art

[0002] Light Emitting Diode (LED) has many advantages such as small size, long life, and high photoelectric conversion efficiency. It is known as the fourth generation of light sources in the history of lighting. In high-power special lighting systems based on LED light sources, such as LED street lights, medical shadowless lamps, ultraviolet LED (UV-LED) exposure light sources, etc., in order to increase the output light power of the system, it is usually necessary to combine a large number of low-power LEDs into an array to form a high-power LED surface light source. In this type of design, the tight arrangement limits the aperture of the LED secondary lens, and naturally limits its optical extension. According to the optical extension conservation principle in non-imaging optics, when the optical extension of the secondary lens is less than the optical extension of the LED, the secondary lens will limit the propagation of light, resulting in a decrease in the utilization rate of light energy. In this type of lighting system with optical extension limitation, starting from the quality of the LED light source beam, choosing an LED light source with the smallest optical extension and the highest optical power as possible has become the key to improving the light energy utilization rate of the lighting system. Studying the optical extension characteristics of LED light sources is also particularly important for the optimization design of array light sources.

[0003] In addition to describing the degree of expansion of the light beam itself, the concept of etendue can also be used to evaluate the light energy utilization rate of the optical system. If the optical etendue of the optical element is greater than the optical etendue of the light source, then the optical element will be able to collect all the light emitted by the light source. On the contrary, if the optical etendue of the optical element is less than the optical etendue of the light source, then the light emitted by the light source will inevitably be restricted in the process of propagating through the optical element. And it will lead to a decrease in light energy utilization. Through the LED near-field optical etendue measurement device, optical designers can select and reasonably match light sources and optical elements to achieve reasonable utilization of light energy. Summary of the invention

[0004] In view of the above deficiencies in the prior art, an object of the present invention is to provide a device and method for measuring the near-field optical etendue of an LED.

[0005] To achieve the above objectives, the technical solutions adopted are:

[0006] One of the purposes of the present invention is to provide a device for measuring near-field optical etendue of LEDs, comprising:

[0007] The light source module comprises a power supply component and an LED light source, wherein the power supply component is electrically connected to the LED light source;

[0008] A first variable lens is disposed on the light-emitting side of the light source module and is used to adjust its own light aperture according to the size of the light-emitting surface of different LED light sources;

[0009] The second variable lens is arranged on a side of the first variable lens away from the light source module, and is used to adjust its own light aperture according to the size of the light-emitting surface of different LED light sources;

[0010] An optical power sensor is disposed on a side of the second variable lens away from the light source module and is used to measure the optical etendue of the LED light source;

[0011] A main control computer is electrically connected to the output end of the optical power sensor and is used to convert the optical signal measured by the optical power sensor into an electrical signal and convert it into near-field light data through data processing;

[0012] The first variable lens is provided with a first variable iris on a side close to the light source module; the second variable lens is provided with a second variable iris on a side close to the first variable lens.

[0013] Furthermore, the LED near-field optical etendue measurement device further comprises:

[0014] The first lens switching server has an input end electrically connected to the main control computer and an output end connected to the first variable iris.

[0015] Furthermore, the LED near-field optical etendue measurement device further comprises:

[0016] The second lens switching server has an input end electrically connected to the main control computer and an output end connected to the second variable iris.

[0017] The beneficial effects of adopting the above technical solution are: the power supply component of the light source module is adjusted according to the working voltage of the LED light source to meet the different working voltages of different LED light sources; a variable aperture is installed in front of the lens, and the lens aperture is changed by changing the size of the aperture; the adjustment of the aperture size is controlled by the lens switching servo; similarly, according to the setting of the main control computer, the lens switching servo synchronously changes the aperture size in front of the two lenses; the optical power sensor can measure the optical power and optical power distribution of the LED light source in real time; according to the optical power distribution of the LED light source on the optical power sensor and the optical magnification of the system, the main control computer calculates the accurate luminous size, luminous angle and radiation distribution of the LED light source in space; the main control computer calculates the luminous size, divergence angle and radiation distribution of the LED light source in space in real time by receiving the electrical signal transmitted by the near-field extension sensor; according to the transmission instruction of the luminous size of different LED light sources, the lens switching servo is controlled to change the aperture size to realize the control closed loop of the entire measurement process.

[0018] The second object of the present invention is to provide a method for measuring the near-field optical extension of LEDs, using the above-mentioned LED near-field optical extension measuring device, comprising the following steps: by adjusting the size of the first variable aperture and the second variable aperture, measuring the optical extension of the light-emitting surface and light-emitting angle of LED light sources of different sizes.

[0019] Furthermore, the LED near-field optical expansion measurement method includes the following steps: controlling the first lens switching server and the second lens switching server through parameter adjustment of the main control computer, thereby adjusting the size of the first variable aperture and the second variable aperture, and measuring the optical expansion of the light-emitting surface and light-emitting angle of LED light sources of different sizes.

[0020] In order to measure the optical etendue of LED light sources, it is necessary to establish an appropriate model to select the light beam emitted by the LED light source. Figure 2 As shown, the LED light source can be regarded as a plane light source in the xoy plane (x is perpendicular to the paper), and the second variable lens used to collect LED light energy belongs to a rotationally symmetric optical system; the entrance pupil diameter of the secondary lens can be expressed as a variable circular aperture D2 in the optical axis direction (OZ), and by adjusting the size of D2, the optical extension amount and its corresponding optical power from different ranges of the LED light source can be obtained. However, considering the asymmetry of the energy distribution of the LED light-emitting surface, for example: the energy density at the edge of the LED light-emitting surface is often weaker than that at the center, this single variable (D2) measurement method may lead to misjudgment of the LED optical extension amount characteristics.

[0021] Therefore, a more reasonable approach is to place another variable aperture D1 in front of the LED light source to intercept light from different areas of the LED light-emitting surface (which can be understood as a more accurate sampling of the light from the LED surface light source). By adjusting the sizes of the two apertures D1 and D2 at the same time, the measurement of optical extension can be completed. Figure 2 shown.

[0022] Since the optical structure of the entire measuring system is rotationally symmetrical, the optical etendue within the two apertures D1 and D2 can be calculated as Figure 3 The line integral shown is calculated according to Figure 3 Geometric relationship, angle θ can be expressed as:

[0023]

[0024] Wherein, θ2 is the angle between the line connecting the lower end point of the first variable iris D1 and the point on the surface of the second variable iris D1 and the normal line of the light; θ1 is the angle between the line connecting the upper end point of the first variable iris D1 and the point on the surface of the second variable iris D1 and the normal line of the light.

[0025] According to the optical etendue expression (2):

[0026] U=∫du=∫∫∫∫n 2 dxdydLdM (2);

[0027] In the formula, n is the refractive index of the space, dxdy is the area of ​​the unit light-emitting element on the light-emitting surface, and dLdM is the solid angle of the light emitted by the light-emitting element. The optical extension can clearly reflect the expansion degree of a beam of light. For example, compared with the laser light source, the light-emitting area and light-emitting angle of the gas discharge light source are relatively large, so its optical extension will also be large.

[0028] Combining equations (1) and (2), the optical etendue U within the range of two variable apertures (D1 and D2) can be expressed as:

[0029]

[0030] Wherein, D1 is the opening diameter of the first variable aperture, D2 is the opening diameter of the second variable aperture, and L is the distance between the first variable aperture and the second variable aperture.

[0031] By adjusting the apertures D1 and D2 in front of the two lenses, the optical expansion of LED surface light sources of different sizes and light output angles can be measured.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention proposes an LED near-field optical extension measurement device and method. The method is based on an accurate near-field model of an LED light source. After the near-field model of the LED light source is measured by a small light source test system SIC-400, the optical extension measurement can be achieved by only tracing the light data therein, which has the advantages of good repeatability, convenience and speed. With the help of the measured optical extension, optical designers can make a direct judgment on the light energy utilization rate of the LED light source, which provides assistance for selecting excellent LED light sources for optical design. The optical extension measurement method of the present invention can meet the application requirements of an optical system with rotationally symmetric properties by adjusting the apertures in front of two lenses, and meet the near-field extension measurement of most LED light sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of the LED near-field optical etendue measurement device of the present invention;

[0035] Figure 2 This is a schematic diagram of the optical etendue of an LED selected by using an aperture in the present invention;

[0036] Figure 3 It is a schematic diagram of calculating the optical etendue within the double aperture constraint range of the present invention. DETAILED DESCRIPTION

[0037] The present invention is described below in conjunction with examples, which are only used to explain the present invention and are not used to limit the scope of the present invention.

[0038] Reference Figure 1 to Figure 3 , a LED near-field optical etendue measurement device, comprising:

[0039] The light source module comprises a power supply component and an LED light source, wherein the power supply component is electrically connected to the LED light source;

[0040] A first variable lens is disposed on the light-emitting side of the light source module and is used to adjust its own light aperture according to the size of the light-emitting surface of different LED light sources;

[0041] The second variable lens is arranged on a side of the first variable lens away from the light source module, and is used to adjust its own light aperture according to the size of the light-emitting surface of different LED light sources;

[0042] An optical power sensor is disposed on a side of the second variable lens away from the light source module and is used to measure the optical etendue of the LED light source;

[0043] A main control computer is electrically connected to the output end of the optical power sensor and is used to convert the optical signal measured by the optical power sensor into an electrical signal and convert it into near-field light data through data processing;

[0044] The first variable lens is provided with a first variable iris on a side close to the light source module; the second variable lens is provided with a second variable iris on a side close to the first variable lens.

[0045] As a preferred embodiment, the LED near-field optical etendue measurement device further includes:

[0046] The first lens switching server has an input end electrically connected to the main control computer and an output end connected to the first variable iris.

[0047] As a preferred embodiment, the LED near-field optical etendue measurement device further includes:

[0048] The second lens switching server has an input end electrically connected to the main control computer and an output end connected to the second variable iris.

[0049] The present invention also provides a method for measuring the near-field optical extension of LEDs, comprising the following steps: by adjusting the sizes of a first variable aperture and a second variable aperture, measuring the optical extensions of light-emitting surfaces and light-emitting angles of LED light sources of different sizes.

[0050] As a preferred embodiment, the optical etendue U is:

[0051]

[0052] Wherein, D1 is the opening diameter of the first variable aperture, D2 is the opening diameter of the second variable aperture, and L is the distance between the first variable aperture and the second variable aperture.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for measuring near-field optical etendue of LED, characterized in that: include: The light source module comprises a power supply component and an LED light source, wherein the power supply component is electrically connected to the LED light source; A first variable lens is disposed on the light-emitting side of the light source module and is used to adjust its own light aperture according to the size of the light-emitting surface of different LED light sources; The second variable lens is arranged on a side of the first variable lens away from the light source module, and is used to adjust its own light aperture according to the size of the light-emitting surface of different LED light sources; An optical power sensor is disposed on a side of the second variable lens away from the light source module and is used to measure the optical etendue of the LED light source; A main control computer is electrically connected to the output end of the optical power sensor and is used to convert the optical signal measured by the optical power sensor into an electrical signal and convert it into near-field light data through data processing; The first variable lens is provided with a first variable iris on a side close to the light source module; the second variable lens is provided with a second variable iris on a side close to the first variable lens.

2. The LED near-field etendue measurement device according to claim 1, characterized in that: Also includes: The first lens switching server has an input end electrically connected to the main control computer and an output end connected to the first variable iris.

3. The LED near-field etendue measurement device according to claim 2, characterized in that: Also includes: The second lens switching server has an input end electrically connected to the main control computer and an output end connected to the second variable iris.

4. A method for measuring the near-field optical etendue of LEDs, characterized in that: The LED near-field optical etendue measuring device as claimed in any one of claims 1 to 3 comprises the following steps: by adjusting the sizes of the first variable aperture and the second variable aperture, the optical etendues of the light emitting surfaces and light emitting angles of LED light sources of different sizes are measured.

5. The method for measuring near-field optical etendue of LED according to claim 4, characterized in that: The method comprises the following steps: controlling the first lens switching server and the second lens switching server through parameter adjustment of the main control computer, thereby adjusting the sizes of the first variable aperture and the second variable aperture, and measuring the optical expansion of the light-emitting surface and light-emitting angle of LED light sources of different sizes.

6. The method for measuring near-field etendue of LED according to claim 5, characterized in that: The optical etendue U is: Wherein, D1 is the opening diameter of the first variable aperture, D2 is the opening diameter of the second variable aperture, and L is the distance between the first variable aperture and the second variable aperture.

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