|
It is convenient to apply three-dimensional (3D) detecting instruments to automatic drive, virtual reality modeling,
terrain reconnaissance, etc. It is presented that a new high-speed camera which achieves one three-dimensions image by
only one light pulse in this paper. It has a measurement range of one kilometer and a distance resolution of five meters.
This camera is composed with a pulse laser and three receivers which are made up with a Micro Channel Plate (MCP)
and a Charge Coupled Device (CCD) each. These parts are mature commercial productions that provide low cost and
high reliable to the 3D camera. As soon as the pulse laser emits a light pulse, the three receivers are modulated with
synchronistical control circuits. A 3D picture can be calculated by three different density images which are obtained by
that. The one-light-pulse-one-picture mode gives a flexible way to work with a gate signal. A 3D camera working with
high-speed gate signal can achieve high-speed photography easily. A mathematic model is established to describe
measurement range, distance detection precision and space resolving of the camera. The best modulation functions of the
receivers are given with consideration of white noise by Euler-Lagrange equation. Due to the best modulation function
we give a scheme is follows: The first receiver is modulated by a const gain, the second one is modulated by a linearly
increasing gain and the last one is modulated by a linear decreasing gain. This combination achieve both low noise and
simple structure. Because of the simple structure, several fibers which we named amending fibers can be used to amend
error of receiver modulation and synchronistical error. Analysis of the detection precisions of the camera and continuous
wave detection systems are carried out both in time domain and frequency domain. The results indicate pulse laser can
increase the detection range by suppressing background light greatly and decreasing imaging time. But it achieves lower
precision if the background light is faintness. Simulation experiment results are presented in this paper. A 1.4 kilometers
fiber was used in this experiment to simulate a 700 meters distant, a Laser Diode (LD) is employed to simulate the pulse
laser. A high voltage modulation circuit was designed to modulate the gain of MCP to implement the modulation
function. The experiment results with and without amending fibers indicated that the primary noises come from CCD and
the high voltage modulation circuit. The amending fibers can weaken the circuit errors in some degree. Future
improvement is described in the end of the paper also.
|
