Sources of Photoelectric Rangefinder Ranging Errors
The ranging error of the photoelectric range finder is divided into two parts:
(1) Proportional error: an error proportional to the measured distance length, mainly caused by frequency error, atmospheric refractive index error and vacuum light velocity measurement error to the ranging result. The influence of the speed of light measurement error on the ranging value is negligible.
(2) Fixed error: the inherent error of the instrument, which has nothing to do with the measured distance length, including the verification error of the zero point error, the centering error between the instrument and the mirror, the phase measurement error, the amplitude and phase error, the phase inhomogeneity error of the luminous tube and cycle error. The periodic error mainly comes from the same-frequency interference of the photoelectric signal inside the instrument, and the size of the error occurs repeatedly based on the length of the precision measuring ruler.
Among them, the proportional error, period error and zero point error are the main system errors of the photoelectric range finder.
According to a large number of measured data, it is shown that due to factors such as the phase inhomogeneity of the light-emitting tube and the receiving tube of the instrument and the amplitude and phase errors, the instrument also has a correction item related to the distance in addition to the frequency error and the atmospheric refractive index error. The length-related correction numbers are collectively called the multiplication constant!. The correction number of the zero point error is called the additive constant. Systematic errors can be eliminated by applying corrections to obtain systematic error values during verification. Therefore, the verification of the photoelectric rangefinder system error mainly includes the following three items:
(1) Verification of periodic error;
(2) Verification of additive constant;
(3) Verification of multiplying constants.
