Optical Biosafety Test and Analysis of High Power LED Street Lamp

1 Introduction

With the continuous progress of LED technology, the efficiency of LED is increasing and the brightness is improving. The era that led light will not cause harm to human body in the past is gone forever. Developed countries and regions such as Europe and North America have begun to pay close attention to the optical biosafety of LED products and set about formulating a series of standards. However, the domestic research on LED optical biosafety testing technology is still very weak, and there are few research papers on related testing systems and methods.

In this paper, a high-power LED street lamp widely used in LED lighting is tested for optical biosafety. Firstly, the irradiance, radiance and apparent light source are tested. Finally, the hazard types of the test results are analyzed and classified. Based on the fact that the LED light source for general lighting will not produce infrared spectra above 800nm, this experiment only tests the spectral range of 200nm 800nm.

The basic parameters of the lamp are as follows: voltage 220 V, current 0.3248 a, power 65.98 W, power factor 0.9231 and frequency 50 Hz; The luminous flux of the lamp is 5747.3 LM, the central light intensity is 1727.33 CD, the maximum light intensity is 2839.16 CD, and the maximum light intensity angle c: 180.0 ° γ: 59.0 °, light efficiency 87.11 LM / W, relevant color temperature 4632 K, color rendering index RA = 69.1, chromaticity coordinate x = 0.3617y = 0.3949 u = 0.2062 v = 0.3378.

2 irradiance test

Generally speaking, the light distribution design of LED street lamp is designed according to the needs of road lighting, so the field brightness value obtained at the central axis of the street lamp is often not the maximum value, and the maximum light intensity direction of the sample is: C: 180.0 ° γ: 59. 0°。 Considering that the test needs to be conducted according to the maximum hazard direction of street lamp, special fixture shall be used during measurement, and the maximum light intensity direction of fixed lamp shall be perpendicular to the end face direction of detector.

In this experiment, the spectral radiation analyzer is used, and the spectral test range is 200nm 930nm. Before the irradiance test, the spectral analyzer shall be calibrated first. The experimental device is shown in Figure 1.

Due to the large span of the test spectrum range, two different light intensity standard lamps must be used for the calibration and correction of the spectrum analyzer. Among them, 300 Ma constant current powered standard deuterium lamp is used for spectral calibration of 200 nm 350 nm; For the calibration of 350nm 800nm spectral signal, the standard tungsten halogen lamp is used as the light intensity standard lamp.

The test system adopts the method of opening the light mixing ball as the input port of the detector. The small light mixing ball can fully receive the photometric signal in front of the detector. Due to the strong directivity of the photometric signal in the measurement of the optical biosafety system, the light mixing ball can also make a good cosine correction to the directivity of the tested lamps when fully receiving the photometric signal.

In addition, the random reflection of the internal material of the light mixing ball will polarize the incident light. After multiple reflections, the incident light with the same spectral characteristics can be filled with the incident aperture of radiation, so as to avoid the difference of polarization characteristics of incident light at different angles.

After calibration, remove the light intensity standard lamp, install the LED street lamp to be tested, and measure the irradiance of the sample. In general, the maximum illuminance for general lighting is 500 LX, so this illuminance is used to measure when evaluating general lighting lamps. In addition, the hazard value of the light source is calculated by weighting the hazard function after spectral scanning. The variation of the hazard weighting function of blue light is very large, so the measurement wavelength interval is set to 1nm in this system to ensure the accuracy of the test results.

Measure the illuminance value generated at the end face of the light mixing ball in the direction of the maximum light intensity angle of the lamp (C: 180.0 ° / G: 59.0 °). Adjust the distance of the lamp to generate 500 LX illuminance on the end face, and fix the distance for spectral test. It should be noted that the physiological avoidance distance of human eyes is 200mm. Considering the principle of the worst expected service conditions in the use of lamps, it must be ensured that the test distance is greater than 200mm.

Obtain the relative spectral power value of the lamp under 500 LX illuminance, and the measured illuminance spectral distribution is shown in Figure 2:

The spectral irradiance test results of lamps in various bands are automatically obtained by collecting data through software:

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