Investigation Into The High-speed Pulsed Laser Diode 3D-imaging Ladar

The related theory and critical technology of ladar, the imaging mode and ranging methods of imaging ladar have been discussed in detail in this dissertation. Then a research project of high-speed 3D-imaging ladar using a laser diode has been proposed, and the primary and critical problems of the theory and technology of the project have been discussed. A ladar prototype has been manufactured successfully, with which lots of systematic experiments have been carried out. The results of the experiments indicate that the main performance of the ladar prototype matches the design requirement theoretically. The ladar prototype has many advantages, such as high imaging speed, high image resolution, high ranging precision and high quality intensity image, which can be obtained simultaneously.Firstly, the related theory of ladar is discussed in general. Based on the Lambert law of cosines, a form of ladar equation, which is easy to apply, is deduced. An effective method of calculating the maximum detectable distance is proposed based on the theory of signal detects statistics. The output noise and signal-to-noise ratio of avalanche photodiode (APD) are discussed in detail. The characteristics of laser transmission in air are discussed, and the transmissivity of 905nm laser in the near distance in air is calculated. The laser scatter's characteristics of the objects are computed based on the Lambert law of cosines, while the scatter's characteristics of sun light and moon light are calculated separately using the illuminance of sun light and moon light on the ground. The radiation characteristics of the objects are computed using the Plank law.Secondly, the imaging mode and ranging methods of the imaging ladar are analyzed in detail, and the proposed research project of high-speed 3D-imaging ladar is explained. The project adopts pulsed laser ranging in noncoherent detect mode, uses a 905nm pulsed laser diode as the laser source, detects object with a single APD, adopts an optics-mechanics scanner in object space to obtain images, and obtain distance images and intensity images of object simultaneously.Thirdly, a ladar transmitter with high repetition rate which uses pulsed laser diode is manufactured. The power characteristics, spectrum characteristics and temperature characteristics of the laser diode are discussed. The principle of the laser diode driver of the transmitter is discussed and the main characteristics of the laser diode driver are simulated. The main characteristics of the optical system of the transmitter are analyzed and simulated, and the transmissivity, the output laser radiation angle and output laser shape of the optical system of the transmitter are tested in the experiments.Fourthly, a wideband and low noise ladar receiver is manufactured. The focus, field of view and transmissivity of the optical system of the receiver are analyzed. A high-speed transimpedance amplifier circuit is designed with optimized noise. Through the noise model...