Abstract: A real-time FROG system provides ultra fast pulse measurement and characterization. The system includes direct, integrated feedback that measures how well the system is retrieving pulses and tracking changes in the pulse train. This feedback is provided in real time and may be in the form of the FROG trace error, the display of the measured and retrieved FROG trace, accuracy of background subtraction or other quality measurement. The system includes preprocessing options that can be used to adjust the dynamic range of the measured signal or to perform different types of filtering. The preprocessing of the FROG trace precedes phase retrieval processing and improves the quality of pulse retrieval.

Abstract: An apparatus under one embodiment comprises at least a portion of a bearing or bushing having a memory shaped material for expanding against a surface of a structure.

Abstract: An apparatus and method for differential spectral interferometry comprising providing an interferometer comprising a light source; employing an element to provide a dithered relative phase shift between target and reference arms of the interferometer, detecting output from the interferometer, demodulating signals received from the detector at different multiples of the dither frequencies, generating more than one real-valued interferograms from demodulated signals, and using the real-valued interferograms to obtain the complex spectral interferogram.

Abstract: An external cavity laser and a method of generating laser light via an external cavity laser comprising emitting laser light from a source, collimating light output by the source, receiving collimated light with a diffraction grating, reflecting light received from the diffraction grating back to the diffraction grating with a cavity feedback mirror, wherein at least a portion of the mirror is curved, and tuning the external cavity laser to a set of wavelengths.

Abstract: An apparatus, software, and method for segregating out background signals from a signal of interest comprising sampling a signal that includes the background signals over one or more periods of time, forming a matrix from results of the sampling, calculating a matrix of basis functions via a singular value decomposition of the matrix from the forming operation, and determining a set of basis functions to employ to segregate out background signals. Also a corresponding wavelength modulation spectroscopy apparatus, software, and method.

Abstract: An apparatus and method for spectral interferometry comprising providing an interferometer comprising a light source and dithering an element to provide a continuous relative phase shift between target and reference arms of the interferometer.

Abstract: An apparatus, software, and method for segregating out background signals from a signal of interest comprising sampling a signal that includes the background signals over one or more periods of time, forming a matrix from results of the sampling, calculating a matrix of basis functions via a singular value decomposition of the matrix from the forming operation, and determining a set of basis functions to employ to segregate out background signals. Also a corresponding wavelength modulation spectroscopy apparatus, software, and method.

Abstract: An apparatus and method for optical pulse characterization comprising employment of an intensity modulator receiving optical pulses, a spectrometer receiving output from the intensity modulator, a detector receiving output from the spectrometer, a phase shifter receiving a gate pulse and providing output to the intensity modulator, and information processing means receiving output from the detector and providing commands to the phase shifter.

Abstract: An apparatus and method for spectral interferometry comprising providing an interferometer comprising a light source and dithering an element to provide a continuous relative phase shift between target and reference arms of the interferometer.

Abstract: A non-invasive electro-optic probe and probe method for probing electric fields in semiconductor devices comprising directing laser output at a semiconductor device to be probed employing a laser having an operating wavelength such that photon energy of a second harmonic wavelength of the operating wavelength is below the band gap of a semiconductor comprised by the semiconductor device and detecting second harmonic wavelength but not operating wavelength radiation from the semiconductor device.

Abstract: An apparatus and method for determining wave characteristics from wave phenomena. The apparatus and method employ eigenvectors to yield a variety of wave characteristics from wave phenomena data.

Abstract: A process for improving moisture analyzers or hygrometers that use optical absorption techniques to measure water vapor. Water vapor in the optical path outside the sample region is treated to exchange the hydrogen atoms for deuterium, so that the adsorbed water vapor is converted to heavy water, D.sub.2 O, and isotopically mixed HDO, thus reducing or eliminating the interference in any optical absorption apparatus for measuring water vapor, provided the spectral resolution is sufficient to resolve normal water absorptions from heavy water absorptions.

Abstract: The pulse shape I(t) and phase evolution x(t) of ultrashort light pulses are obtained using an instantaneously responding nonlinear optical medium to form a signal pulse. A light pulse, such a laser pulse, is split into a gate pulse and a probe pulse, where the gate pulse is delayed relative to the probe pulse. The gate pulse and the probe pulse are combined within an instantaneously responding optical medium to form a signal pulse functionally related to a temporal slice of the gate pulse corresponding to the time delay of the probe pulse. The signal pulse is then input to a wavelength-selective device to output pulse field information comprising intensity vs. frequency for a first value of the time delay. The time delay is varied over a range of values effective to yield an intensity plot of signal intensity vs. wavelength and delay.