Illumination optical inspection, especially for strategic emerging industries, LED illumination optical inspection is a comprehensive technology that is very broad, practical, and not covered in many aspects of school teaching. Moreover, in the standard and test methods, some optical detection problems such as the LED standard reference lamp in the integrating sphere relative measurement method have not been solved internationally. Therefore, it is indeed a problem to do the accuracy and consistency of optical inspection of LED illumination. Many of our current competency verification comparisons are also limited to focusing on and analyzing the comparison results reported by various testing organizations. We have not really carried out the process of human, machine, material, legal and environmental aspects of each testing organization. Inspection and monitoring. Therefore, the comparison results submitted by some testing institutions in the comparison activities have greater contingency, and some have real doubts. If the testing organizations do not truly achieve the unification of the five aspects of human, machine, material, law and ring, it is impossible to achieve accuracy and consistency and fundamentally improve their own capabilities. This is a process that requires effort. In order to minimize various measurement errors, the inspection agency should first do its best to detect the organization itself from five aspects. The following articles are discussed separately for reference.
one person
People are the most critical factor in doing anything. It is very important to train a strong grassroots inspection team. To do optical inspection, especially LED optical inspection, the inspection personnel should have a certain optical professional foundation and interdisciplinary knowledge, be familiar with the standard, and must consciously follow the strict inspection system and unified operation procedures, and have certain practical experience. .
This is especially true for optical inspection leaders who should be good at discovering even the ability to detect problems with conditioned reflexes. With strong practical experience and profound professional theoretical foundation, we can observe, analyze and judge to solve problems. The optical basics required for traditional lighting and LED illumination optical inspection are optical, physical optics, photometry, colorimetry, and optical definitions, terms, and illumination measurement standards in various traditional lighting and LED lighting standards, as well as instruments. The principle, advantages and disadvantages of the equipment and so on.
In practice, for optical measuring instruments such as integrating spheres, photometric distribution meters, illuminance meters, luminance meters, colorimetric measuring equipment, etc., they should have good practical experience in operation, and have better ability to develop and produce various lighting products. (Including traditional and LED, to have a comparison to be able to identify).
Second, the machine
The illumination optical measuring equipment includes an integrating sphere testing system, a light color distribution testing system, an illuminance meter, a luminance meter, an optical radiation power meter, and a photobiosafety measuring system. The integrating sphere testing system is commonly used or used by testing organizations and enterprises to measure the light color and electrical parameters of the lamp. It has the advantages of low cost of purchase, simple and convenient operation, and fast test speed, but there are many factors that limit its measurement accuracy and consistency. Regardless of the size of the impact, the main potential influencing factors in the integrating sphere test system are analyzed first.
(1) The basic working principle of the integrating sphere measurement method
The principle of the integrating sphere measurement method is to measure the measured light in the integrating sphere first, then measure the measured light, and then compare the relative measurement by the computer. When the lamp under test is similar to the standard reference lamp in all respects, the error is reduced to a minimum. But even then, there are many factors in the actual equipment and testing process that cause it to deviate, not to mention the large difference between most of the lamps tested and the standard reference lamps. Although some factors deviate from the ideal situation, a single factor has little effect on the measurement results. However, there are too many factors that deviate from the ideal, and the greater the possibility of cross-correlation, the greater the error. Therefore, we should minimize the deviations in equipment and testing.
1. The working principle of the spectrometer in the integrating sphere measurement method
The integrating sphere measurement method is divided into photometry and spectrometry. In the early days, simply using the pointer photoelectric galvanometer to read the photocurrent in the photometric probe, and then using the manual calculation method, the error is very large, and it has long been used. It was later improved to read with a digital meter, but it was still out of date for a long time. At present, much more is used in integrating sphere spectroscopy. It can be divided into two types: photomultiplier tube and CCD array.
(1) Working principle inside the photomultiplier tube spectrometer
The complex color light emitted by the lamp under test is uniformly mixed in the integrating sphere and then received by the fiber input end, and transmitted by the optical fiber into the spectrometer, and then filtered into the input slit, and projected onto the grating to decompose the spectral optical power signal.
Since the photomultiplier tube as photoelectric conversion cannot distinguish the spectrum itself, the mechanical device rotates the grating to project a monochromatic optical power signal of a certain bandwidth to the output slit in accordance with the wavelength, and is received by the photomultiplier tube closely attached to the slit. The optical power signal is converted and multi-stage amplified into an electrical signal, and then further amplified by an external circuit and output to a computer for processing. In this series of processes, the technology is very complicated.
In addition, the measurement requires accurate wavelength scanning (this is not a problem for the measurement accuracy of the spectrum continuous lamp, but it is important for the light color parameters of the lamp of the separated spectrum, especially the color parameter measurement accuracy, such as the color temperature measurement accuracy of the incandescent lamp. The color temperature measurement accuracy of the three-color energy-saving lamps is very high. The resolution and accuracy of the measurement are closely related to the input and output slit width, wavelength positioning and scanning step size. Therefore, the measurement speed of the photomultiplier tube spectrometer is slow, and the early spectrometer generally takes 2 to 3 minutes, and the recent one takes about 10 seconds.
.jpg)
The measurement accuracy of the photomultiplier tube spectrometer can be very high, but the photomultiplier tube also has disadvantages: 1 The sensitivity is lowered due to strong light irradiation or due to excessive irradiation time, and will partially recover after stopping the irradiation. This phenomenon is called “tirednessâ€. ". In a 90-minute continuous measurement of the same incandescent lamp using a photomultiplier tube spectrometer for many years, the luminous flux continuously decreased by 3% in one direction, but the color temperature change was very small within 5K (0.2%); The sensitivity of each point on the surface of the cathode is not uniform; 3 the voltage applied in the actual measurement is too high to generate noise.
Agricultural Greenhouse Solar Panels
Shengtian New Energy (Shenzhen)Â Co., Ltd. , https://www.stenergysolar.com