A lidar with a laser transmitter for transmitting a laser beam and a receiver having receiving optics for detecting radiation reflected back from the beam by aerosol particles in the atmosphere, the receiver having an optical axis aligned with the beam. The receiver includes a number of radiation receiving elements such as concentric radiation detector elements placed in the receiving optics focal plane so that these concentric detector elements can measure backscatter radiation from the beam at several fields of view simultaneously. Backscattered signals at fields of view larger than the laser beams's divergence are due to multiple scattering. The unknown backscatter coefficient can then be eliminated by ratioing the lidar returns at the different fields of view.

A semiconductor surface is provided comprising a plurality of light sensitive pixels wherein each pixel of the plurality of pixels comprises an electronic circuit formed on or in the semiconductor surface, the circuit comprising: a photosensor that generates a signal responsive to light incident thereon at an output thereof; and circuitry that provides a signal responsive to a time lapse between a first time responsive to said signal and a reference time. There is also provided a 3D camera incorporating the semiconductor surface.

A frequency monitoring system constructed of a rack mountable instrument for monitoring laser pulse frequency. The pulsed laser frequency is displayed on a linear bar-graph array composed of Light Emitting Diodes (LED's). The display is calibrated so that each LED represents a radio frequency (RF). When the transmitter laser pulses, the laser pulse is reflected by the target object and detected by the receiver and amplified. A small amount of the laser pulse transmitted is detected and mixed with a stable local oscillator signal to produce an RF burst that is sent to the frequency monitor and converted to TTL levels with a high-speed TTL voltage comparator. The TTL signal is fed into the clock input of a binary counter which is cleared and gated by a synch pulse from the transmitter. The output of the binary counter is sent to a digital to analog converter which converts it into an output voltage that is in turn amplified and used as reference points for LED dot/bar driver IC's. The LED drivers provide input for the linear array of LED's selected to operate in a bar length mode or a moving dot mode.

A system and method for measuring the profile of an external surface of a part is provided. The system includes a source of light that directs light onto a region of the external surface of the part. The system also includes a linear, light-sensitive sensor, and a lens used to image locations within the region onto the sensor. The source of light and the sensor are located substantially within the same plane such that the sensor detects substantially only light scattered, diffracted, or reflected from the region and travelling substantially within the plane. The system additionally includes a re-positionable mirror that re-directs the light emitted from the source of light to the plurality of locations within the region and re-directs light scattered, diffracted, or reflected from the plurality of locations within the region to the lens and the sensor. An automatic gain control system which controls the output power of the source of light to thereby avoid saturating the exposure of the sensor may also be included in the above system. Further, a spring which functions as a low-pass filter may be used to couple the motor to the shaft of the rotating mirror. In another embodiment, a re-positionable polygon mirror system comprising standoffs with tangs which restrict the outside reflecting mirror surfaces to pre-aligned planes during rotation of the polygon mirror system is disclosed. A fail-safe eye safety technique is also disclosed which controls the power to the source of light. Even further, an optical scanning system is disclosed which utilizes bi-cell photo-detectors to determine the angular position of the source of light with high precision.

A system and method for measuring the profile of an external surface of a part is provided. The system includes a source of light that directs light onto a region of the external surface of the part. The system also includes a linear, light-sensitive sensor, and a lens used to image locations within the region onto the sensor. The source of light and the sensor are located substantially within the same plane such that the sensor detects substantially only light scattered, diffracted, or reflected from the region and travelling substantially within the plane. The system additionally includes a re-positionable mirror that re-directs the light emitted from the source of light to the plurality of locations within the region and re-directs light scattered, diffracted, or reflected from the plurality of locations within the region to the lens and the sensor. An automatic gain control system which controls the output power of the source of light to thereby avoid saturating the exposure of the sensor may also be included in the above system. Further, a spring which functions as a low-pass filter may be used to couple the motor to the shaft of the rotating mirror. In another embodiment, a re-positionable polygon mirror system comprising standoffs with tangs which restrict the outside reflecting mirror surfaces to pre-aligned planes during rotation of the polygon mirror system is disclosed. A fail-safe eye safety technique is also disclosed which controls the power to the source of light. Even further, an optical scanning system is disclosed which utilizes bi-cell photo-detectors to determine the angular position of the source of light with high precision.