Accuracy of a laser rangefinder receiver

A method of generating a range correction value for a time-of-flight laser rangefinder receiver comprising:

• detecting a return pulse and generating a return pulse signal;
• determining a width of the return pulse;
• providing a range correction value based on the width of the return pulse;
• determining a range of the return pulse;
• and
• providing the range correction value based on the width and the range of the return pulse;
• wherein a plurality of range correction values are stored during a calibration procedure in a lookup table matrix;
• wherein the calibration procedure comprises:
• providing a single laser source;
• splitting an output of the laser source into a T0 channel and a return channel;
• providing a programmable attenuator and a plurality of fiber optic delays that can be switched in and out in the return channel to simulate a plurality of return pulses having various ranges and amplitudes;
• and
• performing the procedure for multiple ranges and echo signal amplitudes for the simulated return pulses with a proper correction amount servoed for zero range error in each condition set into the lookup table matrix.

A time-of flight laser rangefinder receiver comprising:

• a detector for generating a return pulse signal;
• means for determining a width of the return pulse signal;
• means for providing a range correction value based on the width of the return pulse;
• and
• means for determining a range of the return pulse;
• wherein the range correction value is based on the width and the range of the return pulse;
• wherein a plurality of range correction values are stored during a calibration procedure in a lookup table matrix, with a proper correction amount servoed for zero range error in each condition set into the lookup table matrix;
• further comprising at least one laser source, and
• in the case of a single laser source, further comprising means for splitting an output of the single laser source into a T0 channel and a return channel;
• a programmable attenuator and a plurality of fiber optic delays that can be switched in and out in the return channel to simulate a plurality of return pulses having various ranges and amplitudes;
• and
• in the case of two laser sources, a delay generator for generating a first output pulse for a first of the two laser sources to generate a T0 pulse simulating a firing pulse and for generating a plurality of selectable second output pulses for a second of the two laser sources to simulate a plurality of delayed return pulses, and a programmable attenuator acting on the pulses.