The LADAR acronym stands for laser detection and ranging. The term laser is the expansion of Light Amplification by Stimulated Emission &Radiation.
LADAR operates on the same principle that of RADAR laser radar constitutes a direct extension of conventional RADAR techniques to a very short wavelength. Because of they operate at a much shorter wavelength ,laser radar is capable of higher accuracy and more precise resolutions.
Modern laser radar systems combine the capabilities of Radar and optical systems to allow simultaneous measurement of range ,reflectivity ,velocity, temperature & elevation angle. These dimensions of target information can be utilized in fire control & weapon system applications to allow the target acquisition, tracking .classification & imaging.
Useful lasers operating at a wavelength in the UV, VISIBLE & INFRA via Telescope . -The scattered target radiation can be detected and processed in a laser radar receiver to remotely determine the target characteristics.
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1. INTRODUCTION
The LADAR acronym stands for laser detection and ranging. The term laser is the expansion of Light Amplification by Stimulated Emission &Radiation.
LADAR operates on the same principle that of RADAR laser radar constitutes a direct extension of conventional RADAR techniques to a very short wavelength. Because of they operate at a much shorter wavelength ,laser radar is capable of higher accuracy and more precise resolutions.
Modern laser radar systems combine the capabilities of Radar and optical systems to allow simultaneous measurement of range ,reflectivity ,velocity, temperature & elevation angle. These dimensions of target information can be utilized in fire control & weapon system applications to allow the target acquisition, tracking .classification & imaging.
Useful lasers operating at a wavelength in the UV, VISIBLE & INFRA via Telescope . -The scattered target radiation can be detected and processed in a laser radar receiver to remotely determine the target characteristics.
II. DETECTION TECHNIQUES
A LADAR receiver convert the photons of light collected by the receiver aperture & a choice in the design of such a system must be made between two well known techniques .The first & more sophisticated technique is called HETERODYNE DETECTION & the second and simpler one is called ENERGY DETECTION.
The heterodyne detection represents a direct extension of lower frequency heterodyne receiver techniques. Energy detection decisions are based on the result of energy measurement.
HETERODYNE DETECTON:
The model adopted for heterodyne detection LADAR is illustrated in fig. 1. The transmitter consists of low power continuous wave source followed by a pulsed laser amplifier and transmitting optics. By means of a pair of beam splitters a portion of the CW signal is sent to the receiver ,where it serves as a local oscillator.
The pre -detection portion of the receiver consists of receiving optics ,an optical filter to reduce background interference & a photo detector, on which the local oscillator and the target light is present, (fhe photo current consists of a photo mixing component at a frequency given by the Doppler shift introduced by a medial target motion| The local oscillator frequency could be offset to any desired amount from subsequent signal processing hardware considerations , so that photo mixing component would appear at a frequency given by Some of offset and Doppler shift.
ENERGY DETECTION:
The model adopted for an energy detection LADAR is illustrated in fig.2,
The transmitter consists of pulsed source of coherent optical radiation followed by a transmitting optics.
The receiver consists of an energy collecting optics, an optical filter, a photo detector, photo detection processing circuits And finally a decision apparatus