Sources of distance error in optical distance measuring devices
Optical rangefinder distance measurement error is divided into two parts.
(1) Proportional error: the error proportional to the length of the measured distance, mainly by the frequency error, the atmospheric refractive index error and vacuum speed of light determination error to the ranging results of the error. Among them, the speed of light determination error on the ranging value of the impact is negligible.
(2) Fixed error: the inherent error of the instrument, which has nothing to do with the length of the measured distance, including the checking error of the zero point error, the alignment error of the instrument and the reflector, the phase measurement error, the amplitude phase error, the luminous tube phase inhomogeneity error and the cycle error. Cyclic error mainly comes from the instrument's internal photoelectric signal of the same frequency scrambling, the size of the error is to repeat the cycle of the length of the fine measuring tape.
Among them, the proportion error, cycle error, zero error for the main systematic error of the photoelectric rangefinder.
According to a large number of measured data show that: due to the instrument light-emitting and receiving tube phase inhomogeneity and amplitude phase error and other factors, the instrument also exists in addition to the frequency error and atmospheric refractive index error, and the length of the distance related to the correction term, customarily will be associated with the distance related to the length of the number of corrections collectively referred to as the multiplying constant! The correction of zero error is called plus constant. Systematic error can be eliminated by calibration in the systematic error value and the imposition of the correction method. Therefore, the verification of the systematic error of the photoelectric rangefinder mainly includes the following three items.
(1) the verification of the cycle error.
(2) Adding the constant of the calibration.
(3) multiplication constant calibration.
