What is the testing principle of the illuminance meter?
Human beings and all living creatures live in a world of light. Without light, life activities will cease. In the practice of human beings reusing natural light sources and inventing artificial light sources, they make relative comparisons of photometry all the time. Photometry is widely used in daily life. Therefore, manufacturers have developed a variety of photometers, among which illuminance meters are A sort of.
An illuminance meter (or lux meter) is an automatically printed optical fiber and an optical testing instrument for measuring artificial light and natural light intensity. It solves the problem of continuous measurement of light intensity and automatic recording. It is composed of a light detector, an automatic shifting amplifier circuit, a curve recording device, a digital printing device and an instantaneous digital display device. The curve recording device uses an optical fiber frictionless recording method, and the light detector is a filter and blue silicon It is composed of photovoltaic cells so that the visible spectrum response curve conforms to the human visual spectrum curve specified by the International Commission on Illumination (CIE).
The testing principle of the illuminance meter: a photoelectric element that directly converts light energy into electrical energy. Illumination is the area density of luminous flux received on the illuminated plane. An illuminance meter is used to measure light intensity (illuminance), which is the degree to which an object is illuminated, that is, the ratio of the luminous flux obtained on the surface of the object to the illuminated area. It is one of the most commonly used instruments in illumination measurement.
Structural principle of the illuminance meter: The illuminance meter consists of two parts: a photometric head (also called a light-receiving probe, including a receiver, a V (λ) pair filter, and a cosine corrector) and a reading display. Selenium (Se) photovoltaic cells or silicon (Si) photovoltaic cells are commonly used as illuminance meters, also known as lux meters.
Requirements for the use of the illuminance meter: The illuminance meter probe is made of glass, which is easy to be dropped and damaged, and the waterproof effect is very poor when used at the same time.
1. Photovoltaic cells should use selenium (Se) photovoltaic cells or silicon (Si) photovoltaic cells with good linearity; they can maintain good stability for a long time and have high sensitivity; when the E is high, use photovoltaic cells with high internal resistance, which have low sensitivity and linearity. Good, not easily damaged by strong light;
2. There is a V (λ) correction filter inside, which is suitable for illumination of light sources with different color temperatures and has small error;
3. Add a cosine angle compensator (opalescent glass or white plastic) in front of the photovoltaic cell because when the incident angle is large, the photovoltaic cell deviates from the cosine law;
4. The illuminance meter should work at room temperature or close to room temperature (photocell drift changes with temperature changes).
Classification of illuminance meters:
1. Visual illuminance meter: It is inconvenient to use, has low accuracy and is rarely used;
2. Photoelectric illuminance meter: Selenium photovoltaic illuminance meter and silicon photovoltaic illuminance meter are commonly used.
