Abstract: A beam-relay optical system is provided. The beam-relay optical system may include a single-mode optical fiber. The beam-relay optical system may also include a mode matching component. The beam-relay optical system may also include an optical resonator, where the optical resonator may include a cavity. The beam-relay optical system may also include a relay optical component. The relay optical component may relay an output of the mode matching component to the optical resonator.

Abstract: Systems and methods for coherent beam combining are provided. In some aspects, a system may comprise a first array of laser emitters configured to emit a first array of output beams along a first optical path. The system may also comprise a first array of collimating lenses configured to collimate the first array of output beams. The system may also comprise a first lens configured to focus the first array of output beams at a first focal plane. The system may also comprise a first phase screen configured to combine the first array of output beams at the first focal plane to generate one or more first coherently combined beams. Each of the one or more first coherently combined beams corresponds to a phase combination of the first array of output beams.

Abstract: Systems configured to provide illumination of a specimen or to inspect a specimen are provided. One system includes a light source configured to generate pulses of light at a repetition rate. The system also includes optical elements arranged in a first interferometer configuration followed by a second interferometer configuration. The optical elements are configured to quadruple the repetition rate of the pulses of light. In addition, the system includes an electro-optic phase modulator configured to receive the pulses of light from the optical elements and to alter a polarization of the pulses of light at a rate of one half the quadrupled repetition rate such that the pulses of light can be directed to the specimen as effectively continuous-wave uniformly polarized illumination.

Abstract: A manipulator for a fiber optic cable assembly (FOCA) provides microradian accuracy in control of the direction of a beam emanating from the FOCA. Such manipulators can control FOCAs to control the incidence angles of beams at a beam combiner in a beam-combining unit. Accordingly, fewer additional optical elements are required for control of input paths in the beam-combining unit. The manipulator and the beam-combining unit are accurate enough for use in an interferometer that combines beams with different frequencies and polarizations. One such interferometer includes a Zeeman split laser providing a heterodyne beam. A beam splitter separates frequency components of the beams, and AOMs increase the frequency separation between the separated beams. The separated beams can be sent via optical fibers to the beam-combining unit, which combines the beams for use in interferometer optics.

Abstract: An interferometer includes a source of a heterodyne beam including frequency components having frequency components with orthogonal linear polarizations. A beam splitter separates frequency components of the heterodyne beams, and one or more AOMs increase the frequency separation between the separated beams. The separated beams can be sent via optical fibers to a beam-combining unit, which combines the beams for use in interferometer optics.

Abstract: A manipulator for a fiber optic cable assembly (FOCA) provides microradian accuracy in control of the direction of a beam emanating from the FOCA. Such manipulators can control FOCAs to control the incidence angles of beams at a beam combiner in a beam-combining unit. Accordingly, fewer additional optical elements are required for control of input paths in the beam-combining unit. The manipulator and the beam-combining unit are accurate enough for use in an interferometer that combines beams with different frequencies and polarizations. One such interferometer includes a Zeeman split laser providing a heterodyne beam. A beam splitter separates frequency components of the beams, and AOMs increase the frequency separation between the separated beams. The separated beams can be sent via optical fibers to the beam-combining unit, which combines the beams for use in interferometer optics.

Abstract: A manipulator for a fiber optic cable assembly (FOCA) provides microradian accuracy in control of the direction of a beam emanating from the FOCA. Such manipulators can control FOCAs to control the incidence angles of beams at a beam combiner in a beam-combining unit. Accordingly, fewer additional optical elements are required for control of input paths in the beam-combining unit. The manipulator and the beam-combining unit are accurate enough for use in an interferometer that combines beams with different frequencies and polarizations. One such interferometer includes a Zeeman split laser providing a heterodyne beam. A beam splitter separates frequency components of the beams, and AOMs increase the frequency separation between the separated beams. The separated beams can be sent via optical fibers to the beam-combining unit, which combines the beams for use in interferometer optics.

Abstract: The present invention provides a continuously tunable external cavity laser (ECL) with a compact form factor and precise tuning to a selected center wavelength of a selected wavelength grid. The ECL may thus be utilized in telecom applications to generate the center wavelengths for any channel on the ITU or other optical grid. The ECL does not require a closed loop feedback. A novel tuning mechanism is disclosed which provides for electrical or mechanical tuning to a known position or electrical parameter, e.g., voltage, current or capacitance, with the required precision in the selected center wavelength arising as a result of a novel arrangement of a grid generator and a channel selector. The grid generator exhibits first pass bands which correspond to the spacing between individual channels of the selected wavelength grid and a finesse which suppresses side band modes of the laser. The channel selector exhibits second pass bands that are wider than the first pass bands.

Abstract: The present invention provides a continuously-tunable external cavity laser (ECL) with a compact form factor and precise tuning. A novel interference filter which may be used to tune the ECL provides an absence of mode-hopping and reduced feedback from both spurious interference and reflections in the external cavity. A novel tuning mechanism is disclosed which provides for mechanical FM tuning of a wide range ECL tuning elements such as: an interference filter, a diffraction element, and a retroreflector. A novel feedback circuit is disclosed which provides closed loop feedback for selecting output wavelength in a laser.

Abstract: An improved interferometric system with reduced air turbulence error. The system includes an optical retarder that functions as a quarter wave plate for two harmonically related frequencies. The retarder may be formed by a pair of quartz disks cut so that the C axis lie in the plane of the disk and are oriented orthogonally relative to each other.

Abstract: The present invention provides an external cavity laser that has wide-range continuous tuning and is compatible with a compact, robust, inexpensive form factor. In an embodiment of the invention a tunable external cavity laser is disclosed. The laser includes a laser amplifier, a retroreflector, a first and second reflector and a translator. The retroreflector is located in a path of the beam provided by the laser amplifier. The first and second reflectors are positioned opposite one another and in the path of the beam between the laser amplifier and the retroreflector. The translator translates at least one of said first reflector and said second reflector to vary the separation between the reflectors along the path of the beam, thereby tuning the laser amplifier. In another embodiment of the invention a method for adjusting wavelength in an optical device is disclosed.

Abstract: An apparatus for measuring the change in position of a stage mirror with reference to a reference mirror when the stage mirror moves between first and second positions. The apparatus includes a light source for generating first and second coincident light beams, the first light beam having a wavelength .lambda..sub.1 and the second light beam having a wavelength .lambda..sub.2 where .lambda..sub.1 =M.lambda..sub.2. The first light beam includes two orthogonally polarized components differing in frequency by a first beat frequency, F.sub.ref (.lambda..sub.1), and the second light beam includes two orthogonally polarized components differing in frequency by a second beat frequency, F.sub.ref (.lambda..sub.2), where F.sub.ref (.lambda..sub.2)=M F.sub.ref (.lambda..sub.1), and M is an integer greater than 1.

Abstract: The signal-to-noise ratio of the correction signal used for second harmonic interferometry is improved in two ways. First, an optical amplifier, tuned to the second harmonic frequency, is positioned in the optical path. Second, a doubling stage is positioned internal to the correction laser.

Abstract: The ideal source for air-turbulence-corrected distance-measuring interferometry is a single laser that generate overlapping beams at two widely separated wavelengths .lambda..sub.1 and .lambda..sub.2. At least one of the wavelengths, as well as the wavelength ratio, must be known to high degrees of accuracy. Furthermore, at each wavelength, the Iaser should produce a pair of orthogonally polarized frequencies with a frequency splitting that is adjustable over the range of approximately 0.5 MHz to 20 MHz to facilitate AC interferemetric distance measurements with a variety of measurement-mirror velocities.

Abstract: A grating tuned external cavity laser having improved mode selectivity and stability. A cylindrical lens is positioned between a laser amplifier and a prism pair beam expander to focus the laser beam to form a linear spot on a grating. The location of the cylindrical lens between the laser amplifier and the prism pair minimizes the optical length of the laser cavity. In this way, the wavelength separation between optical resonance modes is increased, and the mode selectivity and stability of the system is enhanced.

Abstract: An electrically tunable optical oscillator. An acoustooptically tunable filter is located in a feedback path of an optical oscillator. The filter non-collinearly diffracts the light signal to selectively tune the oscillator. In one embodiment the light signal passes twice through a single filter in a single transit around the feedback path. In another embodiment the light passes through a pair of filters which are arranged such that any frequency shift created by one is cancelled by the other.

Abstract: A grating tuned external cavity laser having improved mode selectivity and stability. A cylindrical lens is positioned between a laser amplifier and a prism pair beam expander to focus the laser beam to form a linear spot on a grating. The location of the cylindrical lens between the laser amplifier and the prism pair minimizes the optical length of the laser cavity. In this way, the wavelength separation between optical resonance modes is increased, and the mode selectivity and stability of the system is enhanced.

Abstract: An etalon stabilized external cavity laser. The present invention is embodied in an external cavity laser and utilizes a servo circuit to adjust the angle of an intra-cavity etalon to suppress multimode operation of the laser. The servo circuit employs a diode detector to detect a beat frequency that occurs during multimode laser operation. The output from the diode is amplified, compared and integrated to produce a control signal. This signal is used to control the angle of the etalon and thereby suppress the multimode operation of the laser.

Abstract: An external cavity laser is formed by feeding back light from a laser through two or more acoustooptic tuneable filters back to the laser. The Doppler shifts introduced by the filters do not entirely cancel. The net Doppler shift caused by the filters is continuously tuned to cause the bandpass of the filter to follow the shifting resonating frequency of the laser to prevent mode hopping.

Abstract: A grating tuned laser system having an anamorphic optical section (72) that produces a line image on the grating (73). This system is insensitive to tilt of the grating (73) about an axis (T) perpendicular to the rulings (74) of the grating (73). An embodiment that utilizes a degenerate external cavity is also insensitive to small lateral misalignment of the optical elements.