The requirements for the use of the illuminometer:
1. The illuminance meter should work at room temperature or close to room temperature (photocell drift changes with temperature)
2. Selenium (Se) photovoltaic cells or silicon (Si) photovoltaic cells with good linearity are used in photovoltaic cells; they can maintain good stability after long-term operation, and have high sensitivity; when high E, choose high internal resistance photovoltaic cells, which have low sensitivity and linearity Good, not easy to be damaged by strong light
3. There is a V (λ) correction filter inside, which is suitable for the illumination of different color temperature light sources, and the error is small
4. A cosine angle compensator (opal white glass or white plastic) is added in front of the photocell because when the incident angle is large, the photocell deviates from the cosine rule
