Illuminance meter usage steps and illumination calibration
①Turn on the power.
②Open the photodetector cover and place the photodetector horizontally in the measurement position.
③Select the suitable measurement gear.
If only "1" is displayed on the left end of the display, it means that the illumination is excessive, and you need to press the range key (⑧ key) to adjust the measurement multiple.
④The illuminance meter starts working and displays the illuminance value on the display screen.
⑤The data displayed on the display screen is constantly changing. When the displayed data is relatively stable, press the HOLD key to lock the data.
⑥Read and record the observed values displayed in the reader. The observed value is equal to the number displayed on the readout multiplied by the span value.
For example: 500 is displayed on the screen, the status displayed in the lower right corner is "×2000", and the illumination measurement value is 1000000lx, that is (500×2000).
⑦Press the lock switch again to cancel the reading value lock function.
⑧ During each observation, take three consecutive readings and record them.
⑨After each measurement is completed, press the power switch key to cut off the power.
⑩Cover the photodetector cover and put it back into the box.
Illumination calibration
Calibration principle:
Let Ls illuminate the photocell vertically → E=I/r2. By changing r, the photocurrent values under different illumination can be obtained. The current scale is converted into the illumination scale based on the corresponding relationship between E and i.
Calibration method:
Use a light intensity standard lamp to change the distance l between the photovoltaic cell and the standard lamp at an approximate working distance of the point light source, record the readings of the ammeter at each distance, and calculate the illuminance E according to the inverse square distance law E=I/r2, as This can get a series of photocurrent values i with different illuminances, and draw the change curve of photocurrent i and illuminance E, which is the calibration curve of the illuminance meter. From this, the dial of the illuminance meter can be graded, which is the calibration curve of the illuminance meter.
Factors affecting the calibration curve:
Photocells and galvanometers need to be recalibrated when replaced; the illuminance meter should be recalibrated after being used for a period of time (generally it should be calibrated 1-2 times 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 different standard lamps can be used, and a small-range galvanometer can be used.
