Introduction and working principle of light meter
1. Illuminance meter:
A luminometer (or illuminometer) is a special instrument for measuring luminosity and brightness. For measuring light intensity (illuminance)
It is the degree to which the object is irradiated, that is, the ratio of the luminous flux obtained on the surface of the object to the irradiated area. Light meters usually consist of selenium photovoltaic cells or silicon photovoltaic cells and a microammeter.
2. Measurement principle:
A photovoltaic cell is a photoelectric element that directly converts light energy into electrical energy. When the light irradiates the surface of the selenium photovoltaic 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, and a photoelectric effect is generated on the interface. The magnitude of the generated photocurrent is proportional to the illuminance on the light-receiving surface of the photocell. At this time, if an external circuit is connected, a current will flow, and the current value will be displayed on a microammeter with a scale of lux (Lx). The magnitude of the photocurrent depends on the intensity of the incident light. The illuminometer has a shift device and can measure high and low illuminance.
3. Types of illuminometers:
(1) Visual illuminance meter: inconvenient to use, low precision, rarely used
(2) Photoelectric illuminance meter: commonly used selenium photovoltaic illuminance meter and silicon photovoltaic illuminance meter.
