Measurement Of LED Grow Light Products

Writer：Jane Time：2018-06-14 Browse：155

In recent years, with the rapid development of facility agriculture, there are more and more researches on plant lighting. With its unique advantages, LED light source has been widely used in the field of plant lighting. Due to the optical parameters of plant growth light environment has certain requirements, so you need to have the corresponding measurement technology and instruments to accurately measure the optical parameters of light environment is in line with the corresponding plant growth needs, to choose the suitable light source, to determine the number and arrangement of the light source, according to the reasonable demand for light source application development to provide appropriate solutions. In recent years, with the rapid development of facility agriculture, there are more and more researches on plant lighting. With its unique advantages, LED light source has been widely used in the field of plant lighting. Due to the optical parameters of plant growth light environment has certain requirements, so you need to have the corresponding measurement technology and instruments to accurately measure the optical parameters of light environment is in line with the corresponding plant growth needs, to choose the suitable light source, to determine the number and arrangement of the light source, according to the reasonable demand for light source application development to provide appropriate solutions.

When used for plant cultivation lighting, LED lighting products should not only consider the basic photometric and radiometric performance, also should be based on the characteristics of the photosynthesis of plants in light quantum systems and plants photometric system considerations photon density and plants of the plants by exchanges photometric parameters, and comprehensive evaluation of the performance of the plant lighting source.

Key factors of plant lighting and requirements for lighting products
First, the quality of light. Plants generally rely on chlorophyll in their leaves to absorb light, and their absorption bands are generally in the blue and red regions, as shown in Figure 1. Absorbed light is converted into organic energy by photosynthesis in plants, which is used for growth and reproduction. Therefore, for plant lighting products, the first consideration should be given to the irradiance of the absorption band, which is generally 400nm~500nm blue and 600nm~700nm red, as well as the spectral composition, range, peak wavelength and color temperature of the selected combination of plant lighting.

Second, the density of light. Different light densities of plants will directly affect the growth, development and structural characteristics of plants. If the optical density is weakened, the same crop will be reduced, flower bud differentiation will be delayed, ovary dysplasia and other phenomena. Because the response characteristics of plants and human eyes to the spectrum are different, the light perception of human eyes is generally measured in the photometric system, while the photosynthesis of plants is generally measured and evaluated in the photometric system and the photometric system of plants, and the evaluation parameter is light quantum flux density (PPFD). Through a large number of studies, McCree has shown that between 400 nm and 700nm, the evaluation of the effective radiation energy of photosynthesis by using optical quantum flux density is in good agreement with the actual photobiological effect.

Third, light uniformity. Due to the strong directivity of LED luminescence and the possibility of the uniform distribution of spatial light and color, the uniformity of radiated illumination on the exposed surface of plants should also be investigated in large-scale planting occasions to obtain a high quality and uniform lighting environment.

Finally, the days are long. Different plants have different demands on the spectrum and different growth stages have different demands on the spectrum. The artificial light supplement in facility agriculture must follow the photophysiological characteristics of plants in order to achieve the best light supplement effect. Therefore, it is necessary not only to accurately measure the spectral composition of the LED light source, but also to know the change of illumination with time.

Measurement of LED lighting products for plant growth
In the past, in the field of plant lighting, light quantum meter is often used to measure, but the actual matching of spectrum is difficult to achieve perfect matching, and even the mismatching will be relatively serious, which has a great impact on the measurement accuracy. With the development of spectral measurement technology, the measurement technology and equipment based on spectral method are becoming more and more mature, and gradually applied to the field of plant lighting detection.

The corresponding spectral curve of plant photosynthesis is different from the spectral optical efficiency curve of human eyes. Therefore, when evaluating the irradiation effect of various light sources, it is necessary to evaluate the irradiation effect according to the spectral response curve of plants. The spectral method not only does not have any mismatching problem, but also can evaluate the performance of lighting products in terms of light quality, light density and light uniformity in the full spectral range. However, there are some problems in the general spectral measurement, such as poor linearity and stray light, which limit the measurement accuracy and put forward new requirements for the measuring equipment.

Summary
The performance evaluation of LED plant lighting products involves multiple measurement systems, with many evaluation parameters and a narrow spectrum. Both the test hardware and software have higher requirements, such as the matching problem of light radiation detector and the precision of spectral measurement.

LED plant lighting manufacturers and related scientific research institutions should choose the appropriate measurement scheme according to their own or standard requirements, based on the impact of lighting on plants, comprehensively and objectively evaluate the performance of LED plant lighting products, and then design plant growth lighting system or light supplement scheme, so as to achieve green lighting and efficient lighting.