Principles and Classification of Lux Meters: How Do Lux Meters Work?
Principle of illuminance measurement: A photovoltaic cell is a photoelectric component that directly converts light energy into electrical energy. When light is incident on the surface of the selenium solar cell, the incident light passes through the metal thin film 4 and reaches the interface between the semiconductor selenium layer 2 and the metal thin film 4, generating a photoelectric effect at the interface. The magnitude of the potential difference generated is proportional to the illuminance on the surface of the photovoltaic cell receiving light. At this point, if an external circuit is connected, a current will flow through, and the current value will be indicated on a microampere meter with lux (Lx) as the scale. The magnitude of photocurrent depends on the strength of the incident light and the resistance in the circuit. The illuminance meter has a gear shift device, so it can measure both high and low illuminance. Types of illuminance meters: 1. Visual illuminance meter: inconvenient to use, low accuracy, rarely used 2. Optoelectronic illuminance meter: commonly used selenium solar cell illuminance meter and silicon solar cell illuminance meter
Measurement principle of illuminance meter:
A photovoltaic cell is a photoelectric component that directly converts light energy into electrical energy. When light is incident on the surface of the selenium solar cell, the incident light passes through the metal thin film 4 and reaches the interface between the semiconductor selenium layer 2 and the metal thin film 4, generating a photoelectric effect at the interface. The magnitude of the potential difference generated is proportional to the illuminance on the surface of the photovoltaic cell receiving light. At this point, if an external circuit is connected, a current will flow through, and the current value will be indicated on a microampere meter with lux (Lx) as the scale. The magnitude of photocurrent depends on the strength of the incident light. The illuminance meter has a gear shift device, so it can measure both high and low illuminance.
Types of illuminance meters:
1. Visual lux meter: inconvenient to use, low accuracy, rarely used
2. Optoelectronic lux meter: commonly used selenium photovoltaic cell lux meter and silicon photovoltaic cell lux meter. Composition and usage requirements of photovoltaic cell lux meter:
1. Composition: microampere meter, shift knob, zero adjustment, terminal block, photovoltaic cell, V (λ) correction filter, etc. Commonly used selenium (Se) or silicon (Si) photovoltaic cell illuminance meter, also known as lux meter
2. Usage requirements: ① The photovoltaic cell should be a selenium (Se) photovoltaic cell or a silicon (Si) photovoltaic cell with good linearity; Long term work can still maintain good stability and high sensitivity; When using high E, choose a photovoltaic cell with high internal resistance, which has low sensitivity and good linearity, and is not easily damaged by strong light irradiation. ② It is equipped with a V (λ) correction filter, suitable for the illumination of different color temperature light sources, with small errors. ③ Add a cosine angle compensator (milky white glass or white plastic) in front of the photovoltaic cell because when the incident angle is large, the photovoltaic cell deviates from the cosine rule. ④ The illuminance meter should work at or near room temperature (the drift of the photovoltaic cell changes with temperature)
