Brief introduction to the function and principle o

Introduction to the function of illuminometer

an automatic printing optical fiber illuminometer is an optical testing instrument for measuring the intensity of artificial light and natural light It solves the problems of continuous measurement of light intensity and automatic recording It is composed of light detector, automatic shift amplifier circuit, curve recording device, digital printing device and instantaneous digital display device The curve recording device adopts optical fiber frictionless recording mode, and the optical detector is composed of filter and blue silicon photocell, so that the visible spectral response curve conforms to the human visual spectral curve specified by the International Commission on illumination (CIE) A pocket electronic illuminance meter belongs to the technical field of illuminance measurement, which is suitable for measuring illuminance in agricultural production, daily life and outdoor travel. It adopts a photosensitive resistor as a photoelectric converter, which contains a DC power supply, which is successively connected in series with the voltage conversion circuit, switch, photosensitive resistor, test circuit, a/D converter, decoder, display driver and display at the output end of the DC power supply. The utility model avoids the use of a photometric head, and the DC power supply can only use a 3V battery. The decoder, the display driver and the display are integrated on an integrated circuit card, making it simple in structure, small in size, easy to move, and sensitive in response. The utility model relates to an ultraviolet irradiance meter, which belongs to an optical testing instrument. Its feature is that it consists of two unidirectional cut-off optical filters and two identical photoelectric receivers, and the circuit part adopts two-way amplification, so that the radiation value of the required test band can be accurately measured. The test principle of strong stray light cut-off illuminance is the area density of the received luminous flux on the illuminated plane. Illumination juice is used to measure the exposed 1. Tensile strength test of thermal insulation materials (jgj144 ⑵ 004 technical specification for external wall external insulation engineering); The instrument of illuminance on the surface is one of the most used instruments in illuminance measurement. Structure principle of illuminance meter illuminance meter consists of photometric head (also known as light receiving probe, including receiver, V（ λ) It is composed of filter, cosine corrector) and reading display. 4、 Measurement steps and methods in the working room, the illumination should be measured at each working place (such as desk and workbench), and then averaged. For empty rooms or non working rooms where the working place is not determined, if general lighting is only used, a horizontal plane with a height of 0.8m is usually selected to measure the illumination. Divide the measurement area into squares of equal size (or close to squares), measure the illumination EI in the center of each square, and its average illumination is equal to the average value of the illumination at each point, that is, in the formula, EAV - the average illumination of the measurement area, LX; EI -- illuminance at the center of each measuring grid, LX

n - number of measurement points. Illuminance uniformity refers to the ratio of the minimum illuminance on the specified surface to the average illuminance, that is, Emin refers to the minimum illuminance on the measured surface, LX. In this experiment, the measuring point surface arranged in the room can be the designated surface, and the minimum illumination can be regarded as the minimum illumination value in the measuring point. The side length of each square in the measurement room is LM. In the formula of large room, EAV - the average illumination of the measurement area, LX

ei -- illuminance at the center of each measuring grid, LX

n - number of measurement points. Illuminance uniformity refers to the ratio of the minimum illuminance on the specified surface to the average illuminance, that is:

where Emin refers to the minimum illuminance on the measured surface, LX

in this experiment, the measuring point surface arranged in the room can be the designated surface, and the minimum illumination can be regarded as the minimum illumination value in the measuring point. The side length of each square in the measurement room is LM, and 2-4 M can be taken for large rooms. Measuring points are arranged along the centerline of the length direction in narrow and long traffic sections such as walkways and stairs, with a spacing of 1 - 2 m, which is difficult to be widely accepted; The measurement plane is the ground level or 151 above the ground level, and the production capacity of the oil refining industry is more than 0mm. The more the number of measuring points is, the more accurate the average illumination value is, but it also takes more time and energy. If the allowable measurement error of EAV is ± 1 and the special committee is built into a united, upward, learning and innovative community organization, 0%, the workload can be reduced by selecting the least measuring points according to the chamber shape index. The relationship between the two is listed in Table 1. If the number of lamps is exactly equal to the number of measuring points given in the table, the measuring points must be increased. Table 1 Relationship between chamber shape index and measuring points chamber shape index Kr minimum measuring points chamber shape index Kr minimum measuring points ＜ 142 ～ 3161 ～ 29 ≥ 325, where l and W are the length and width of the room, and HR is the height from the lamp to the measuring plane. When the general lighting is supplemented by local lighting, the illumination of the working point shall be measured according to the normal working position of the person, and the photocell of the illuminometer shall be placed on the working surface or the operation surface for visual operation. An ideal illuminometer should have the following conditions: ● compact size and light weight illuminometer is widely used, and the opportunity of application is often in different places. Therefore, small price and light weight of portable illuminometer is the first prerequisite. ● accuracy: whether the illuminometer is good or bad has an absolute relationship with its accuracy. Of course, it is also closely related to its price, so it is necessary to buy an illuminance meter with high accuracy at a reasonable price, generally with an error of no more than ± 15%. ● the types of color compensation light sources are all inclusive, some of which focus on red high-voltage lamps with longer wavelengths, or blue purple lamps with shorter wavelengths, such as daylight fluorescent lamps; There are also incandescent bulb series with relatively average distribution. The sensitivity of the same illuminometer to different wavelengths may be slightly different, so appropriate compensation is necessary. ● cosine compensation as we all know, the brightness of the illuminated surface is related to the incident angle of the light source. In the same way, when measuring with an illuminance meter, the incidence angle of the sensor and the light source will naturally affect the reading value of the contrast meter. Therefore, whether a good illuminometer has the function of cosine compensation cannot be ignored