Abstract: A laser distance measuring apparatus in which source beams from two lasers are combined and focused on a target. One beam is continuous wave and one has periodic narrow pulse envelopes. After reflection the composite reflected beam is redivided in a diffraction grating and compared with two respective reference beams by means of two photodetectors. Doppler data are provided, as well as separate high resolution and low resolution range output data. Integration of the Doppler data in a computer, and combination of the three data signals there, enable an unusually complete and accurate record of the shape of the target even if the shape has many severe discontinuities, as in the case of a turbine rotor. An alternative embodiment provides for switching the pulse time of flight portion of the system to utilize various harmonics of the pulse envelope waveform.

Abstract: A closed loop optical gauge directs a laser beam toward an object whose radial velocity, instantaneous position, and/or shape are to be measured, and utilizes the Doppler frequency shift of the reflected beam to make measurements. A reference sample of the original direct beam has its frequency shifted by an acoustooptical modulator. A closed loop system is created by sensing the difference in frequency between the reflected beam and the shifted reference beam. The amount of frequency modulation is then controlled so that the frequency of the shifted reference beam continuouly tracks that of the reflected beam, preferably with a fixed offset of frequency. The output can be integrated with respect to time to obtain position or shape information.Absolute distance to the object is measured by transmitting a train of pulses of light toward the object and receiving reflected light pulses back.

Abstract: A hybrid laser distance gauge utilizes complementary simultaneous measurements based upon both Doppler and time of flight principles. A complete record can be produced of the location and shape of a target object even when the object has severe discontinuities such as the edges of a turbine blade. Measurements by the two principles are made by using many optical elements in common.The Doppler measurements have an open loop optical/electronic arrangement in which the Doppler shift is converted to a voltage by a phase locked loop. The time of flight measurements are made at one or more harmonic frequencies of a mode locked pulse envelope wave train, for unusually accurate and unambiguous distance data.