Abstract: An optical system comprising a concave primary mirror reflects light through an intermediate focus to a secondary mirror. The secondary mirror re-focuses the image to a final image plane. Optical limiter material is placed near the intermediate focus to optically limit the intensity of light so that downstream components of the optical system are protected from intense optical transients. Additional lenses before and/or after the intermediate focus correct optical aberrations.

Abstract: An apparatus and method for wavefront sensing that includes: employing two moiré gratings in an optical path; optically Fourier transforming a moiré deflectogram produced by the gratings; variably transmitting the transformed moiré deflectogram; and receiving an image of the variably transmitted and transformed moiré deflectogram. The variable transmission is best accomplished by transmission filter, a transmissive optic encoding intensity information upon the moiré deflectogram as a function of fringe angle. For example, the function can be a triangular transmission function centered on the (0,0) order spatial frequency spot and oriented at 45 degrees to the y-axis. The optical Fourier transform is accomplished by a lens and the variable transmission by an apodized slit.

Abstract: A bi-directional pulsed ring laser that produces bi-directional light pulses that interact in such a way that they are phase conjugated. A nonlinear substance, such as a nonlinear crystal or fluid, that has an index of refraction that is dependent upon light intensity is located near a beam waist of the laser cavity to provide a self-lensing effect. Methods for reducing dead band beyond observable limits are also provided. The increased sensitivity of the bi-directional pulsed ring laser provides application in detecting magnetic susceptibility by detecting the change in phase between the arrival times of the bi-directional pulses at a modulator and the electrical signal of the modulator to determine the change in frequency of a coil that has magnetic susceptibility.

Abstract: A measuring device completely determines the characteristics of light pulses in a beam of ultrashort light pulses using optoelectronic detectors instead of second harmonic generating crystals. An optical system provides a spatial dispersion of an ultrashort pulse in at least one dimension. A two slit filter intercepts the dispersed beam whereby the transmitted spectra combine to provide a beat frequency within selected limits. An optoelectronic detector detects the beat frequency and outputs a signal functionally related to the beat frequency that contains spectral phase information that is sufficient to characterize the pulse. In another embodiment, a beam splitter splits the beam into first and second beams, wherein one of the beams is time delayed and the other beam is spectrally dispersed. The two beam are recombined to provide information about the spectral phase of the ultrashort pulse. The pulse is completely characterized when the spectral phase information is combined with amplitude information.

Abstract: A laser gyroscope comprising two ninety degree turning prisms optically connected. A non-reciprocal gain layer structure is grown on the hypotenuse face of one prism.

Abstract: A passively mode-locked laser gyro having a saturable absorber in constant motion. The saturable absorber is mechanically vibrated or rotated in a direction transverse to the longitudinal pulses passing through the absorber. The vibrational or rotational motion of the absorber dithers the effective scattering error source. The saturable absorber may be a multiple quantum well device. The multiple quantum well device may be attached to two dither drives to provide continuous circular motion of the multiple quantum well device. The motion generator can generate both linear and non-linear motion. The passively mode-locked laser qyro may be constructed from fiber optics with a bias modulator and gain medium.

Abstract: A ring laser gyro that minimizes and avoids the effects of lock-in and backscatter. A ring laser is pumped in a lasing cavity with a mode-locked laser. Dual counterrotating pumped pulses are precisely positioned to avoid overlay in optical elements that contribute to lock-in and backscatter. The position of the stimulated counter rotating laser beams is controlled by two methods. In the first method the pumped pulses are synchronized with a wave propagation delay line. In the second method the pumped pulses are chopped by an acousto-optic modulator shutter to precisely time the location of the pumped pulses. Both methods are can be combined to achieve a hybrid synchronized and acousto-optic modulated approach.

Abstract: A laser gyro having a laser source for providing laser energy includes a laser gain device for receiving lasing energy and generating first and second counterpropagating laser pulses along a common optical path. A detector detects at least one of the pulses and generates an index of refraction control signal representative of the detected at least one laser pulse. The index of refraction of a segment of the optical path is varied in response to the index of refraction control signal such that the index of refraction of the segment of the optical path changes an optical path length for one of the laser pulses. A detector senses the beatnote between the first and second counterpropagating laser pulses.

Abstract: A ring laser apparatus for spontaneous-emission-free detection including several mirrors. Some of the mirrors including a first, second and third mirror are arranged to form a laser ring. A gain medium is located between two of the first, second and third mirrors within the laser ring. Radiation from an external radiation source impinges on a fourth mirror and is reflected to illuminate the gain medium. The gain medium thereby produces first and second oppositely traveling laser beams along first and second pathways, each of the pathways having equal path lengths. The first and second oppositely traveling beams each provide an output through one of the laser ring mirrors and are reflected into the beam splitter after respectively striking fifth and sixth mirrors. The gain medium comprises a gain layer having a thickness which is much smaller than a wavelength so that the oppositely directed first and second beams from the gain medium are highly coherent on the beam splitter.