Abstract: A readout system for receiving return signals originating from one or more energy pulses fired toward a scene. The system includes a first mechanism for detecting energy received from the scene and providing a first signal in response thereto. A second mechanism times a rising edge and a falling edge of a pulse contained in the first signal and provides a second signal in response thereto. In a specific embodiment, a third mechanism determines characteristics of the pulse based on the second signal, which include characteristics, such as pulse width, pulse intensity, and/or pulse centroid, sufficient to generate an image of the scene.

Abstract: A multimode remote vibration sensor. The inventive sensor (8) includes a mode locked laser transmitter (10); a receiver (30) adapted to detect signals transmitted by the laser (10) and reflected by an object (22) and a signal processor (40) for analyzing the signals and providing an indication with respect to a vibration of the object (22). The laser is particularly novel as a vibration sensor transmitter inasmuch as it includes a mode locking mechanism. The mode locking mechanism causes the laser to output energy at all modes within the gain profile in phase with one another. The result is a series of tight clean pulses which may be used for range resolved vibration and one-dimensional (high resolution ranging) applications.

Abstract: A synthetic aperture ladar system using a mode locked laser transmitter. The inventive system (12) includes a mode locked laser transmitter (22), a receiver (40) adapted to detect signals transmitted by said laser (22) and reflected by an object (32) and a signal processor (50) for analyzing the signals. The laser (22) is particularly novel as a synthetic aperture ladar transmitter inasmuch as it includes a mode locking mechanism (180). The mode locking mechanism (180) causes the laser to output energy at all modes within the gain profile in phase with one another. The result is a series of coherent pulses which may be used for synthetic aperture ladar applications. In a particular embodiment, the present teachings are implemented in a multifunctional laser which, in its operational mode, outputs a mode locked beam for synthetic aperture ladar.

Abstract: The present invention uses an intra-cavity modulation approach to modulate a laser transmitter at bandwidths greater than a few gigahertz (GHz) in a non-ambiguous waveform by chirping the laser and simultaneously mode locking. Accordingly, the inventive system includes a source of a beam of electromagnetic energy; a mechanism for mode locking the beam; and an arrangement for chirping the beam. In the illustrative embodiment, the source is a laser. The mode locking mechanism may be an active element or a passive element. The beam is chirped with a translation mirror. The translation mirror may be driven with a piezo-electric drive coupled. In the best mode, the carrier is chirped with an electro-optical crystal disposed in the cavity of the laser. The laser is chirped to the free-spectral range limit, which is typically a few hundred megahertz, by scanning the optical length of the laser resonator.

Abstract: A multifunctional laser (10) which, in a first operational mode, outputs a mode-locked beam for vibration sensing applications and, in a second operational mode, outputs a Q switched illumination beam for imaging applications. The inventive laser (10) includes a resonant cavity (110, 120, 190); a gain medium (100) disposed with the cavity; a first arrangement (150) in communication with the medium for causing a Q-switched signal to be transmitted from the cavity; a second arrangement (180) in communication with the medium for causing a mode-locked signal to be transmitted from the cavity; and a mechanism (130, 140) for switching between the first arrangement and the second arrangement.

Abstract: An incoherent ladar transmitter (12) adapted for use with synthetic aperture processing. The system (12) includes a first mechanism (44, 48, 50) for generating a laser beam (18). A second mechanism (44, 68) records phase information pertaining to the laser beam (18) and subsequently transmits the laser beam (18) from the system in response thereto. A third mechanism (40) receives a reflected version (20) of the laser beam and provides a received signal in response thereto. A fourth mechanism (72) corrects the received signal based on the phase information recorded by the second mechanism (44, 68). In a more specific embodiment, the ladar system (12) includes a synthetic aperture processor (46) for correcting the received signal based on the phase information and providing a corrected laser signal in response thereto.

Abstract: A multimode remote vibration sensor. The inventive sensor (8) includes a mode locked laser transmitter (10); a receiver (30) adapted to detect signals transmitted by said laser (10) and reflected by an object (22) and a signal processor (40) for analyzing the signals and providing an indication with respect to a vibration of the object (22). The laser is particularly novel as a vibration sensor transmitter inasmuch as it includes a mode locking mechanism. The mode locking mechanism causes the laser to output energy at all modes within the gain profile in phase with one another. The result is a series of tight clean pulses which may be used for range resolved vibration and one-dimensional (high resolution ranging) applications. In a particular embodiment, the present teachings are implemented in a multifunctional laser which, in its operational mode, outputs a mode locked beam for vibration sensing.

Abstract: An integrated detector and signal processor (31) for ladar focal plane arrays (30) which internally compensates for variations in detector gain, noise, and aerosol backscatter. The invention (31) is comprised of a detector element (42) for receiving an input signal, a circuit (72) for generating a threshold based on the RMS noise level of the input signal, and a circuit (74) determining when the input signal is above that threshold. The detector element (42) is physically located in the interior of the detector array (30), while the signal processing circuitry (50) is located on the periphery of the array (30). In the preferred embodiment, the signal processor (31) also includes a circuit (56) for sampling the input signal and a circuit (58) storing multiple samples, allowing for multiple returns to be detected. In the preferred embodiment, the signal processor (31) can be operated in two modes: self triggered and externally triggered (range-gate mode).

Abstract: A multifunctional laser (10) which, in a first operational mode, outputs a mode-locked beam for vibration sensing applications and, in a second operational mode, outputs a Q switched illumination beam for imaging applications. The inventive laser (10) includes a resonant cavity (110, 120, 190); a gain medium (100) disposed with the cavity; a first arrangement (150) in communication with the medium for causing a Q-switched signal to be transmitted from the cavity; a second arrangement (180) in communication with the medium for causing a mode-locked signal to be transmitted from the cavity; and a mechanism (130, 140) for switching between the first arrangement and the second arrangement.

Abstract: Dual-cavity resonators that may be optimized for multiple functions (operating modes). The dual-cavity resonators provide a first set of operating modes that exhibits low repetition rates (5-20 Hz), high energy per pulse, and long, pulse-width, and a second set of operating modes that exhibits high repetition rates (100-2000 Hz), low energy per pulse, and short pulse-width.

Abstract: A laser radar system employing a linear FM chirp laser followed by post detection pulse compression by a surface acoustic wave (SAW) device. The system includes an FM chirp modulator that provides the needed tuning range and linearity for pulse compression. This modulation is accomplished by using a high-pressure CO.sub.2 laser with an intracavity electro-optic modulator of CdTe. The frequency of the transmitter laser is accurately controlled through the application of high linearity, high frequency, sawtooth voltages to the two plates of the CdTe crystal, with the voltage waveform applied to one plate being out of phase with that applied to the other crystal plate. With the performance the system offers, absolute radar ranges can be measured to 0.22 m and velocities to 0.37 m/sec.

Abstract: A laser radar system employing a linear FM chirp laser followed by post detection pulse compression by a surface acoustic wave (SAW) device. The heart of the invention is the FM chirp modulator that provides the needed tuning range and linearity for pulse compression. This modulation is accomplished by using a high pressure CO.sub.2 laser with an intracavity electric-optic modulator of CdTe. The frequency of the laser is controlled through the voltage applied to the crystal. With the performance the system offers, absolute radar ranges can be measured to 0.22 m and velocities to 0.37m/sec.

Abstract: A chirp laser system includes an intracavity electro-optical crystal modulated at a relatively high frequency, for example 250 kilohertz, to sweep the frequency of the transmitter laser above and below its nominal center frequency. One of the mirrors of the laser transmitter is adjustable to vary the length of the cavity and to shift the frequency of the transmitter laser. When the frequency of the transmitter laser is shifted, the output amplitude of the laser changes. With the center frequency of the laser at a maximum gain point, the amplitude of the output signals during positive and negative frequency excursions of the transmitter laser will be substantially symmetrical. However, if thermal or other effects cause the frequency of the laser to shift away from the maximum gain point, the output during positive and negative excursions will be asymmetrical.