Calibration and usage of illuminance meter
Calibration principle:
Let Ls irradiate the photocell vertically→E=I/r2, change r to get the photocurrent value under different illuminance, 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, at 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 galvanometer 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; The calibration range of the illuminance meter can be changed from the distance r, and different standard lamps can also be selected, and a small-range ammeter can be selected.
How to use the lux meter
①Turn on the power.
②Open the cover of the photodetector and place the photodetector horizontally at the measuring position.
③Select the appropriate measurement gear.
If only "1" is displayed at the left end of the display, it means that the illumination is too much, and you need to press the range key (⑧ key) to adjust the measurement multiple.
④The illuminance meter starts to work and displays the illuminance value on the display.
⑤The data displayed on the display screen is constantly changing. When the displayed data is relatively stable, press the HOLD key (⑧ key) to lock the data.
⑥Read and record the observed value displayed in the reader. The observed value is equal to the product of the number displayed on the readout and the span value.
For example: 500 is displayed on the screen, the status displayed in the lower right corner is "×2000", and the illuminance measurement value is 1000000lx, that is (500×2000).
⑦Press the lock switch again to cancel the reading lock function.
⑧ For each observation, take three consecutive readings and record them.
⑨ After each measurement is completed, press the power switch key to cut off the power.
⑩Close the photodetector cover and put it back into the box.
