A novel timing control method is utilized in conjunction with an imaging lidar system of the type disclosed in U.S. Pat. No. 4,862,257. This novel timing control is employed in applications wherein the lidar system is mounted on an airborne platform. The timing control method of this invention completely eliminates the glint detector with associated signal conditioner used in the system of U.S. Pat. No. 4,862,257, and instead, relies upon a signal derived from the aircraft altimeter to continually provide platform altitude status. Since the entire system is under the control of a computer, the altimeter signal can be interpreted and used to adjust total delay so as to automatically track changing platform altitude. It is now possible to initiate all timing from the occurrence of the laser "lamp fire" signal. The total delay to camera "gate on" is now the "lamp-to-laser" delay, plus round trip platform altitude delay (computer from the altimeter signal), plus desired water depth delay, less system delays.

Imaging lidar system

A light detection and ranging (LIDAR) system uses dual detectors to provide three-dimensional imaging of underwater objects (or other objects hidden by a partially transmissive medium). One of the detectors is a low resolution, high bandwidth detector. The other is a high resolution, narrow bandwidth detector. An initial laser pulse is transmitted to known x-y coordinates of a target area. The photo signals returned from the target area from this initial pulse are directed to the low resolution, high bandwidth detector, where a preliminary determination as to the location (depth, or z coordinate) of an object in the target area is made based on the time-of-receipt of the return photo signal. A second laser pulse is then transmitted to the target area and the return photo signals from such second laser pulse are directed to the high resolution, narrow bandwidth detector. This high resolution detector is gated on at a time so that only photo signals returned from a narrow "slice" of the target area (corresponding to the previously detected depth of the object) are received. An image of the detected object is then reconstructed from the signals generated by the high resolution detector. In a preferred embodiment, the two detectors are housed in a single digicon tube, with magnetic deflection being used to steer the beam to the appropriate detector.

Dual detector lidar system and method

A non-contact system for detecting printed circuit wiring defects and for measuring circuit feature height relative to a substrate. The system has an energy source for illuminating the substrate and circuit features and a scanner for both instantaneously receiving energy reflected from the substrate and circuit features and for generating a signal in response to the reflected energy, which signal is adapted to vary with the intensity of the reflected energy. An analyzer is connected to the scanner for correlating the generated signal to a measurement representative of the height of the circuit features relative to the substrate. Variations and non-uniformity of the substrate surface due to bending, warpage or other causes can be accounted for so as to provide an accurate measurement of the height of a circuit feature relative to the substrate surface on which it is mounted.

System for measuring and detecting printed circuit wiring defects

Through discrimination of the scattered signal polarization state, a lidar system measures a distance through semi-transparent media by the reception of scattered signals from a first surface and scattered signals from a second surface. Combined and overlapped light signals scattered from the two surface signals can be separated by exploiting their differing polarization characteristics. This removes the traditional laser and detector pulse width limitations that determine the system's operational bandwidth, translating relative depth measurements into the conditions of single surface timing measurements and achieving sub-pulse width resolution.

Remote measurement of shallow depths in semi-transparent media

A gloss sensor for optically measuring the gloss or reflectance of a surface. The gloss sensor includes a light source of emitting a light beam toward a surface to be measured. The gloss sensor also includes a light detecting device arranged to preferentially detect the intensity of the diffusely reflected component of the reflected light beam relative to the specularly reflected component.

Means of enhancing the sensitivity of a gloss sensor

AN IMPROVED OPTICAL DEPTH FINDER, AND ELEMENTS THEREFOR, FOR DEPTH SOUNDING AND DETECTION OF SUBMERGED TARGETS FROM AN AIRBORNE VEHICLE. THE DISCLOSED SYSTEM USES A COHERENT BEAM OF POLARIZED LIGHT FROM A LASER DIRECTED DOWNWARDLY TOWARD THE SURFACE OF A BODY OF WATER AND PROCESSES THE POLARIZED SURFACE SPECULAR REFLECTED ENERGY, ENERGY REFLECTED BY SUBMERGED TARGETS WITHIN THE BEAM, AND ENERGY REFLECTED BY THE BOTTOM OF THE BODY OF WATER TO DERIVE THE DESIRED INFORMATION. MEANS ARE PROVIDED SELECTIVELY TO ATTENUATE THE REFLECTED ENERGY IN ACCORDANCE WITH THE PARTICULAR SOURCE THEREOF SO AS TO PERMIT THE DYNAMIC RANGE OF THE PROCESSOR OF THE REFLECTED ENERGY TO BE REDUCED AND THE SYSTEM TO BE USED WHEN THE HEIGHT OF THE AIRBORNE VEHICLE CHANGES OR CONDITION OF THE WATER VARIES.

C. Mackenzie Gordon

Papers

Optical depth finder and elements therefor