It is proposed to single out two methods for observing object using range-gated vision systems (RGVS). In the first case the distance between RGVS and an object is fixed. Its observation is made by changing time delay between the leading edges of pulses of laser illumination and gate-pulses of the receiving block, i.e. neighboring layers of space are sequentially seen along the optical axis (visibility zone shifts). In the second case time delay is fixed. This corresponds either to observation of object moving along the optical axis of the system or to the study of ensemble of objects in visibility zone at different distances, including the observation on inclined path. It is shown that such a division of the observation methods has a definite physical justification. Division of the two methods for observing object will promote systematization and better understanding of the investigation results on RGVS.
The regularities were investigated of formation of range-energy profiles (REP) of visibility zone for RGVS with illuminating pulses, the shape of which differs from the rectangular (triangular or trapezoidal) one. It was established that if the illuminating pulse length ΔtL is smaller or equal to the length of gate-pulse ΔtG of the receiving block, then the expressions for characteristic distances coincide with the case of rectangular-shaped pulses and they can be used to determine distances to objects for pulses having non-rectangular shape. At ΔtL > ΔtG in a case of illuminating pulses having triangular shape REP possesses bell-like shape. For illuminating pulses having trapezoidal shape REP has either bell-like or trapezoidal shape. The last shape appears when the duration of the upper base of the illuminating pulse having trapezoidal shape exceeds the gate-pulse duration. The empirical method for determining characteristics distances to the REP maximum and boundary points of plateau area, which can be used for calculation of the distance to the object. Using calibration constants the method was proposed for calculating the distances to objects and its efficiency was experimentally proved.
The present paper is aimed to development of the powerful illumination module based on powerful AlGaAs/GaAs laser diode matrix with short laser pulses, high repetition rate, given radiation divergence characteristics and stabilized parameters. Developed modification of the powerful illumination module gives the chance to realize powerful pulse laser radiation on the wavelength of 846 nm with the effective form of the laser pulse, wide range of duration from tens to hundreds of nanoseconds and the frequency of repetition rate of pulses up to 10 kHz in the set space angle of radiation 27° × 8°.
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