Illuminance meter adjustment for brightness
Calibration principle:
Let Ls irradiate the photocell vertically → E=I/r2, change r to get the photocurrent value under different illuminance, and convert the current scale into the illuminance scale according to the corresponding relationship between E and i.
Calibration method:
Using the light intensity standard lamp, under the working distance of the approximate point light source, change the distance l between the photocell and the standard lamp, record the readings of the ammeter at each distance, and calculate the illuminance E by the inverse square law of distance E=I/r2, and then calculate the illuminance E by This can get a series of photocurrent values i with different illuminance, and make the change curve of photocurrent i and illuminance E, which is the calibration curve of the illuminance meter. From this, the calibration of the illuminance meter can be done by dividing the dial of the illuminance meter.
Factors affecting the calibration curve:
Recalibration is required when the photocell and ammeter are replaced; after the illuminance meter has been used for a period of time, the illuminance meter should be recalibrated (generally 1-2 times within a year); high-precision illuminance meters can be calibrated with light intensity standard lamps; expand The calibration range of the illuminance meter can change the distance r, or choose different standard lamps, and choose a small-range galvanometer
