The application of light classification
Visual application: used in lighting, the physical unit is the average human eye as the function of the spectral radiation power weighted by the luminous flux as the main parameters.
Non-visual application: to animals, plants, medical, microbial, identification, data transmission and other applications, the physical unit is the radiation power or light quantum number.
The energy of the photon
LED light is the energy conversion phenomenon, electron and hole complex when the excess energy will produce light, the shorter the wavelength, the higher the energy of the photon, the photon is the smallest unit of light transmission energy, plant photosynthesis absorption Is the energy of the photon, the photosynthesis is carried out in the photon energy package drive, rather than the general role of light energy, which is the plant photosynthesis requires photon to express the reason.
The energy ratio of a single photon at a wavelength of 400 nm to a wavelength of 700 nm is 1.75, that is, the blue light is 1.75 times larger than the red light energy.
The number of photons produced at the same radiated power increases as the wavelength increases.
Photosynthesis is produced by the photon flux, is the energy of photons in the enzyme under the action of decomposition of CO2 and H2O after the new molecules to produce the process, but not all of the plants absorbed by the photon to produce the same photosynthesis, the need for energy transfer Angle understanding of photosynthesis, with "light meal" to understand the relationship between photons and plants.
The photon photon flux (PPF), the wavelength range from 400 to 700 nm, the second is the generated photon flux (YPF), the wavelength range can be based on plant photosynthetic response Determine the wavelength range.
Plant lamp parameters and units
When the basic units of the substance, such as molecules, ions, light quantum, etc., are described, the molar amount is expressed by the basic particles of 6.022EXP (23) substances in units of moles, The number of photons in plant photosynthesis is also expressed in terms of moles, and a photon mole contains 6.022EXP (23) photons. Many of the parameters are expressed in micromoles due to the large number of units in plant photosynthesis.
1 mole (mol) = 1000000 micromoles (umol).
1 micromolar (umol) contains 60 million photons.
Photosynthetic Active Radiation (Photosynthetic Active Radiation)
Plants for photosynthesis in a specific wavelength range (400-700nm) radiation called photosynthetically active radiation, labeling units are two:
First, the use of photosynthetic irradiance (w / m2), mainly used for solar light photosynthesis of the general study.
The second is the photosynthetic photon flux density PPFD (umol / m2s), mainly used for artificial light and sunlight on plant photosynthesis research.
This method of photon flux, which is irradiated to the surface of the plant per second, represents the radiation capacity of the radiation source, called the PPF_PAR method.
PAR accounts for about 50% of the total solar radiation, it should be noted that the photosynthetic irradiance of this unit does not reflect the impact of wavelength.
Photosynthetic Photon Flux (Photosynthetic Photon Flux) refers to the wavelength in the 400-700nm band, the artificial light source per second radiation photon micromolar number, unit umol / s.
Photochemical flux density (Photosynthetic Fluon Flux Density) corresponds to the PPF is the number of micromoles per unit of light emitted per second, the unit umol / m2s, is the concept of density.
PPFD is the PPF that is expressed in the range of one square meter.
PPFD is a physical quantity associated with the radiation distance, inversely proportional to the square of the irradiation distance.
1 PPFD represents 1 micromolar per second of photon radiation on a 1 m 2 surface.
1umol / m2s (PPFD), it means that there are 6 photons in 10 square nanometers.
The resulting photon flux (Yield Photon Flux)
Refers to the amount of photons in the wavelength range emitted by the artificial light source per second, the unit umol / s. Usually the band is considered 360-760nm, for the LED light source, the wavelength range is set to 380-800nm.
The resulting photon flux density (Yield Photon Flux Density)
Corresponding to YPF is the number of micromoles per square meter per second, the unit umol / m2s is the concept of density.
YPFD is YPF in the range of one square meter.
YPFD is a physical quantity associated with the radiation distance, inversely proportional to the square of the distance of the irradiation.
YPFD more accurate expression of LED plant light quality of light.
For red-blue spectra, YPF = PPF, other spectra PPF <YPF.
PAR and PPFD difference, PAR is a physical concept, and PPFD this physical concept of the unit.
PPFD and PPF relationship: PPFD is determined by the planting process parameters of the basic amount, PPF is the main parameters of lamp manufacturing.
In order to clearly understand the three concepts of radiation, lighting, and plant photosynthesis, we have produced the following table.
Artificial light source of radiation, lighting, plant photosynthesis of the three concepts of comparison table:
The right side of the figure is the mounting height. As can be seen from the figure, the appropriate installation height can reduce the light source power and reduce system energy consumption.
For the same PPF light source, the installation height and PPFD relationship is the installation height increase, PPFD to 2 times the rate of decline.
Quantitative analysis parameters between different light sources and lamps
For different artificial light sources, the following parameters can be used to compare the spectral performance between them. These parameters can also compare the spectral performance of different manufacturers under the same spectral form of the same light source. Generally, the larger the value is, the better the value Large does not mean that the planting efficiency is high, the need for professional assessment of professional skills.
PPF / w: represents the PPF produced by each power consumption.
PPFD / w: represents the PPFD produced by each power consumption.
YPF / w: YPF for each power and one watt.
YPFD / w: YPFD for each power consumption.
These values ??are related to the spectral form (light quality). If these values ??are then divided by the price of the plant lamp, the price of the plant lamp can be compared. The validity of these values ??is reliable through a third-party independent professional analysis.
Usually, agricultural sodium lamp up to 2.2 umol / w, LED light source, the largest 2.1 umol / w.
Light quality, light quantity, photoperiod
Light quality LQ
Light quality LQ (Light Quality), is in a certain wavelength range of spectral form, no units.
The amount of light LI
Light Intensity (Light Intensity) is the number of photons that can be irradiated by light. It can be represented by photon flow or photon density. Unit: PPF (YPF) or PPFD (YPFD).
Photoperiod PP (Photo Period), which indicates the sum of the hours of the lights in a natural day, in hours.
The amount of radiation required for the plant every day (important concept)
Many people are keen to study the compensation points and saturation points of plant radiation to calculate how much PPFD should be used for plant lamps. The range from the compensation point to the saturation point is larger (as shown below). The amount of light in this range of selected plant lights has artificial Randomness, compensation point and saturation point is only qualitative analysis, the quantitative process must consider other environmental factors, not mechanical understanding.
In general, the compensation point and the saturation point appear only in a certain period of time, not constant, with the compensation point and saturation point set PPFD is not scientific, in our planting technology expert system, we give the plant per square meter per day Reasonable amount of radiation, the amount of value related to the cost of planting and planting quality, our parameters are reference to agricultural science long-term study of the planting process parameters DLI, with theoretical basis.
Daylighting capacity DLA
DLG (Daily light amount): refers to the artificial light source in the photoperiod per day per square meter of PPFD generated by the number of photons, the unit: mol / m2d.
Since the amount of light in the plant light is constant over the photoperiod, DLA = 0.0036 * PPFD * PP. PP-photoperiod units: hours.
DLA is the planting process parameters, plant plants planted PPFD is needed to use DLA calculated.
Disclaimer: The DLA parameter is defined by the bright solid light source Institute Xu Dong, the reference needs to be noted.
Daylight integration amount DLI
Daily light integral DLI (Daily light integral): refers to the sun under the effective radiation per day per square meter of photosynthetic volume, unit: mol / m2d.
DLI is an important parameter of photosynthesis in traditional cultivation. It is a technical parameter for long-term agricultural science research. It has universal planting guidance significance. In sunlight, due to the photosynthetic irradiance of sunlight (converted to PPFD) with time and weather In the ever-changing, this change will sometimes span between the compensation point and the saturation point, so the DLI needs to be calculated in terms of the integral method. The initial calculation can be calculated using the average PPFD and the effective time (hours).
DLI = 0.0036 * PPFD (average) * effective time calculated in accordance with the average method in the sun. Effective time unit: hours.
In the outdoor planting, DLI parameters will be affected by the saturation point in the greenhouse, the indoor DLI is less than the outdoor DLI, greenhouse DLI will usually be less than DLA, DLA parameter creation, the scientific provision of the greenhouse is filled with light Based on the theoretical basis of the size of the light source, the establishment of DLA database of artificial light source can provide the basic data system of plant plant application, which is of great significance and hope that the agricultural scientific research personnel should participate in this work.
DLA is the main parameter of the planting process of plant and greenhouse. It is the main basis for the design of plant lamp. DLA can be obtained from the experimental data or after DLI is weighted, but the experimental data is needed. The relationship between DLA and DLI is : DLA <DLI, such as lettuce planted DLI 17, DLA 9-11.
Above is the introduction of plant lamp spectral parameters, to understand the plant lamp of these parameters, for the application of plant lights and communication is very important, standardized use of these parameters can be the correct application of plant lamps and research plant lamp spectral technology.