How to calibrate the three-axis relationship of the distance meter

During the use of the rangefinder, the relationship between the three axes of the rangefinder (the telescope sighting axis, the rangefinder transmitting axis and the receiving axis) often changes due to vibration and collision during long-term operation and transportation. The conventional calibration method is simple to operate, but the calibration result is not accurate enough.

1. Calibration principle

     By measuring the range angle value of the return light signal of the rangefinder in the horizontal and vertical directions, the correct dial reading of the four critical states (the weakest return light signal) when the three-axis relationship of the rangefinder meets the requirements is calculated. After rotating the micro-screw to the correct reading position of the dial, calibrate the rangefinder return light signal to the critical state so that the mark of the sighting reflector after correction is in the center of the return light signal range. Take the calibration of the three-axis relationship of the DI2002 rangefinder as an example.

2. Verification of horizontal parallelism

(1) Place the reflector about 200m away from the rangefinder, use the telescope to accurately aim at the reflector mark, and read the horizontal dial reading A (145°04'30'').
 (2)  Slowly rotate the horizontal micro-screw of the theodolite to make the aiming direction deviate to the left from the reflector mark, observe the change of the rangefinder return light signal, until the return light signal is in a critical state (the return light signal is in a state of continuous jumps between one grid and no signal), read the horizontal reading A (144°57'59'').
(3) Use the same method to determine the horizontal disk reading A (145°07'37'') when it deviates to the right of the reflector mark.
 (4) Calculate the horizontal deviation angle according to the following formula:

3. Horizontal parallelism correction
 (1) Calculate the correct angle value when it deviates to the left and right of the reflector mark in the critical state according to the following formula.