Laser radar: from early history to new trends

Abstract

The first steps of laser radar are discussed with the examples from range finding and designation. The followed successes in field tests and further fast development provided their wide use. Coherent laser radar, developed almost simultaneously, tried the ideas from microwaves including chirp technology for pulse compression, and Doppler mode of operation. This latter found a unique implementation in a cruise missile. In many applications, environmental studies very strongly rely upon the lidars sensing the wind, temperature, constituents, optical parameters. Lidars are used in the atmosphere and in the sea water measurements. Imaging and mapping is an important role prescribed to ladars. One of the prospective trends in laser radar development is incorporation of range and velocity data into the image information. Deep space program, even having not come to the finish, gave a lot for 3D imaging. Gated imaging, as one of the 3D techniques, demonstrated its prospects (seeing through scattering layers) for military and security usage. Synthetic aperture laser radar, which had a long incubation period, started to show first results, at least in modeling. Coherent laser radar baptized as the optical coherence tomography, along with the position sensitive laser radar, synthetic aperture laser radar, multispectral laser radar demonstrated very pragmatic results in the micro-scale applications.

Development of pulsed‐laser three‐dimensional imaging flash lidar using APD arrays

“…Moreover, the mechanical robustness of the scanning unit is a substantially challenging issue for this type of pulsed‐laser lidar 42,43 . More importantly, due to the limitation of the scanning speed of the scanning unit, this type of pulsed‐laser lidar often suffers from a low imaging speed and a low frame rate, which limit its imaging efficiency 44,45 …”

“…42,43 More importantly, due to the limitation of the scanning speed of the scanning unit, this type of pulsed-laser lidar often suffers from a low imaging speed and a low frame rate, which limit its imaging efficiency. 44,45 Along a different line of research, the flash lidar obtains the depth information of the target free from the scanning unit, which can guarantee durability and maintenance. Different from the scanning pulsed-laser lidar, the flash pulsed-laser lidar employs a detector array instead of a single detector to detect the echo pulse.…”

Frequency difference stabilization in Y-shaped cavity dual-frequency laser with the aid of precision passive control

“…In recent years, the frequency difference stabilization of dual-frequency lasers has become important in the precise measurement fields for a variety of applications such as velocity and vibration measurement, 1 high-resolution force sensing, 2 laser lidar detection, 3,4 feedback interferometers, [5][6][7] acceleration measurement, 8 atomic clocks, 9 and Doppler velocimeters. 10,11 In these applications, in addition to a large frequency difference tunable range, a low-frequency difference drift of the laser over a long period of time is generally required.…”

Laser radar: historical prospective—from the East to the West

“…Overviews on the history of laser radar development appeared concerning Europe, 9 the United States, 10 the former Soviet Union (FSU), 11,12 Japan, 13 and China. 14 This paper combines and updates those histories.…”