Illuminance calibration of lux meters
Calibration principle:
Make Ls vertically irradiate the photocell → E=I/r2, change r to get the photocurrent value under different illuminance, and convert the current scale into the illuminance scale by 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, calculate the illuminance E by the inverse square law of distance E=I/r2, and 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:
The photocell and ammeter need to be re-calibrated when they are replaced; the illuminance meter should be re-calibrated after a period of use (generally 1-2 times within a year); the high-precision illuminance meter can be calibrated with a light intensity standard lamp; expand The calibration range of the illuminance meter can change the distance r, or choose different standard lamps, and choose a small-range galvanometer
