Abstract: An illustrative cavity ring down gas sensor includes an optical cavity for receiving a gas to be detected and at least two electromagnetic radiation sources. The first electromagnetic radiation source may emit a first beam of light having a wavelength corresponding to an absorption wavelength of the gas to be detected, and the second electromagnetic radiation source may emit a second beam of light having a second wavelength that is off of an absorption wavelength of the gas to be detected. The first beam of light may detect a cavity ring down time decay, which is related to the concentration of the gas to be detected. The second beam of light may be used to detect a baseline cavity ring down time decay, which may be used to help increase the accuracy of the sensor by, for example, helping to compensate the concentration of the gas detected by the first beam of light for sensor variations caused by, for example, sensor age, temperature or pressure changes, and/or other conditions.

Abstract: A method for forming a nanostructure penetrating a layer and the device made thereof is disclosed. In one aspect, the device has a substrate, a layer present thereon, and a nanostructure penetrating the layer. The nanostructure defines a nanoscale passageway through which a molecule to be analyzed can pass through. The nanostructure has, in cross-sectional view, a substantially triangular shape. This shape is particularly achieved by growth of an epitaxial layer having crystal facets defining tilted sidewalls of the nanostructure. It is highly suitably for use for optical characterization of molecular structure, particularly with surface plasmon enhanced transmission spectroscopy.

Abstract: The invention relates to an optical strain gauge using a glass fiber (1) comprising a Bragg grating (2). The glass fiber is coated with a sheath (3) of polyether ether ketone with an admixture of at least 10 weight percent and a maximum of 40 weight percent of an inorganic filler, with a particle size of between 0.08 ?m and 12 ?m. The outer diameter of the sheath (3) is between 0.2 mm and 1.2 mm. The ratio D/d between the outer diameter D of the sheath (3) and the diameter d of the glass fiber (1) is between 2 and 6. A pressure of the sheath (3) on the glass fiber (1) is such that essentially no relative movement can occur between the glass fiber (1) and the sheath (3).

Abstract: A system and method for daylight inspection of a surface, such as a railroad track, is disclosed. The disclosed system includes lasers, cameras, and a processor. The lasers are positioned adjacent the surface. The laser emits a beam of light across the surface at a combined intensity of at least 0.15 watts of intensity per inch of width of the surface, and the camera captures images of the surface having the beam of light emitted thereon. The camera includes a bandpass filter which passes only a band of light corresponding to a dip in solar radiation. The laser is selected to provide an emitted light beam which is more intense than the solar radiation at the dip. The processor formats the images so that they can be analyzed to determine various measurable aspects of the surface. The system and method includes one or more algorithms for determining these measurable aspects of the surface.

Abstract: An apparatus and technique are invented that enhance the sensitivity of a spectrometer for trace gas detection by employing wavelength modulation spectroscopy (WMS) and integrating the absolute value of the recorded spectra across multiple absorption lines (features) of the species. The sensitivity is further enhanced by conducting WMS with large modulation depths. This technique is implemented using a continuously tunable external cavity CW quantum cascade laser to record the second harmonic wavelength modulated spectra of NO2 across the peak of the R-branch from 1629.5 cm?1 to 1633.9 cm?1. By integrating the absolute value of the resulting spectra, the detection sensitivity of NO2 is improved by a factor of 40 compared to the sensitivity achieved using single line WMS with the same apparatus. A sensitivity of approximately 6 ppb can be obtained using a short-path cell (a 1 m absorption cell with 2 passes) which can be significantly improved using multipass cells and cavity enhanced techniques.

Abstract: A linear position array detector system is provided which imparts light energy to a surface of a specimen, such as a semiconductor wafer, receives light energy from the specimen surface and monitors deviation of the retro or reflected beam from that expected to map the contours on the specimen surface. The retro beam will, with ideal optical alignment, return along the same path as the incident beam if and only if the surface is normal to the beam. The system has a measurement device or sensor within the path of the retro or reflected beam to measure deviation of the retro beam from expected. The sensor is preferably a multiple element array of detector-diodes aligned in a linear fashion. A unique weighting and summing scheme is provided which increases the mechanical dynamic range while preserving sensitivity.

Abstract: A system is provided for monitoring a relative displacement of a pair of end-winding components. The system includes a structure mounted to the end-winding components. The system further includes a fiber Bragg grating mounted to a non-curved surface of the structure, where the fiber Bragg grating is configured to reflect incident radiation having a peak intensity at a respective wavelength based on a strain of the fiber Bragg grating. The structure is configured so that the strain produced by the structure limits a magnitude of the strain of the fiber Bragg grating within a predetermined range over a span of the relative displacement of the pair of end-winding components.

Abstract: An arrangement for determining concentration of substances in a fluid comprising a light source for generating primary light pulses within a wavelength interval, a light pulse splitter adapted to split up the primary light pulses into a predetermined number of secondary light pulses to be transmitted through the fluid, the secondary light pulses being separated in time as well as wavelength to be differently absorbed upon passage of the fluid depending on the concentration of the substances, a detector for detecting intensity of the differently absorbed secondary light pulses, and a comparator for comparing the intensities of the differently absorbed secondary light pulses with different reference intensities corresponding to different substances to thereby determine the concentration of the substances in the fluid.

Abstract: An extended range optical imaging system and method for use in turbid media generates a beam of coherent light, modulates the beam of coherent light to encode scan information, directs the modulated beam of coherent light from a first location through the turbid medium toward a target, scans the modulated beam of coherent light over the target in a pattern, according to the scan information, to illuminate the target and to cause light to be reflected, detects the modulated light reflected from the target with a sensor at a second location in the turbid medium to derive an output signal that varies in proportion to the modulated reflected light, demodulates the output signal to derive information comprising the scan information, and constructs an image from the output signal and the scan information so derived.

Abstract: A surface inspection apparatus for observing an edge portion of an object to be inspected includes an illumination device that irradiates an illumination light to the edge portion; and an observation device that forms an image of an observation region of the edge portion illuminated with the illumination light. The illumination device emits a first irradiation beam and a second irradiation beam as the illumination light. The first irradiation beam is incident at approximately right angles to the edge portion for compensating brightness of the image and the second irradiation beam is obliquely incident laterally to the observation region of the edge portion for generating a shadow depending on a surface state of the observation region.

Abstract: An apparatus, for measuring an applied electrical field and for reducing perturbation to the electrical field being measured, includes a laser integrated into an electro optic crystal sensor head prior to the output fiber. A probe beam is passed along the crystal direction of low birefringence of nearly circular optical indicatrix, rather than one of high EO modulation. The EO crystal is placed between two crossed polarizers and oriented such that a small tilt angle is subtended between its optic axis and the path of the probe beam. Improved optical coupling is achieved by using a large core multimode fiber at the output, to reduce optical insertion losses. A collimating lens emits the intensity modulated laser beam back to a photodetector, where the intensity modulated laser beam is converted to an electrical signal representing both field strength and phase of the electrical field applied to the sensor head.

Abstract: Disclosed is a method for reviewing defects in a large number of samples within a short period of time through the use of a defect review apparatus. To collect defect images steadily and at high throughput, a defect detection method is selected before imaging and set up for each of review target defects in the samples in accordance with the external characteristics of the samples that are calculated from the design information about the samples. The defect images are collected after an imaging sequence is set up for the defect images and reference images in such a manner as to reduce the time required for stage movement in accordance with the defect coordinates of the samples and the selected defect detection method.

Abstract: A pattern shape evaluation method and semiconductor inspection system having a unit for extracting contour data of a pattern from an image obtained by photographing a semiconductor pattern, a unit for generating pattern direction data from design data of the semiconductor pattern, and a unit for detecting a defect of a pattern, through comparison between pattern direction data obtained from the contour data and pattern direction data generated from the design data corresponding to a pattern position of the contour data.

Abstract: A gas sensor uses optical interferents in a porous thin film cell to measure the refractive index of the pore medium. As the medium within the pores changes, spectral variations can be detected. For example, as the pores are filled with a solution, the characteristic peaks exhibit a spectral shift in one direction. Conversely, when tiny amounts of gas are produced, the peaks shift in the opposite direction. This can be used to measure gas evolution, humidity and for applications for other interferometric-based sensing devices.

Abstract: A positioning system for determining an angular position of a vehicle (10) with respect to a predetermined position. The system comprises at least one beacon (12) whose position relative to the predetermined position is known, for generating at least one beam of known optical characteristic that allows deriving of the angular position.

Abstract: A method and apparatus for improving the accuracy of in-band OSNR measurements using a conventional polarization extinction or polarization-nulling method. In particular, the severe degradations of the polarization extinction that result from slow and fast polarization fluctuations in the optical signal components during the in-band OSNR measurement are substantially mitigated by rapidly and/or randomly changing the state of polarization prior to conventional polarization control and filtering.

Abstract: A method for analyzing defect information on a substrate, including logically dividing the substrate into zones, and detecting defects on the substrate to produce the defect information. The defect information from the substrate is analyzed on a zone by zone basis to produce defect level classifications for the defects within each zone. The zonal defect level classifications are analyzed according to at least one analysis method. The defect level classifications are preferably selected from a group of defect level classifications that is specified by a recipe. Preferably, the at least one analysis method includes at least one of zonal defect distribution, automatic defect classification, spatial signature analysis, and excursion detection. The defect level classifications preferably include at least one of individual defect, defect cluster, and spatial signature analysis signature.

Abstract: A patterned dielectric layer is evaluated by measuring reflectance of a region which has openings. A heating beam may be chosen for having reflectance from an underlying conductive layer that is several times greater than absorptance, to provide a heightened sensitivity to presence of residue and/or changes in dimension of the openings. Reflectance may be measured by illuminating the region with a heating beam modulated at a preset frequency, and measuring power of a probe beam that reflects from the region at the preset frequency. Openings of many embodiments have sub-wavelength dimensions (i.e. smaller than the wavelength of the heating beam). The underlying conductive layer may be patterned into links of length smaller than the diameter of heating beam, so that the links float to a temperature higher than a corresponding temperature attained by a continuous trace that transfers heat away from the illuminated region by conduction.

Abstract: A system for measuring light absorption levels for a liquid for use in a printing system includes a light source adapted to provide a divergent beam of light, a liquid container with a hole that acts as a focusing lens, and a prism disposed over the hole to split the divergent beam of light into a reference beam and a measurement beam. The systems include a measurement detector to measure the intensity of the focused beam to produce a liquid measurement signal. A reference detector measures the intensity of the reference beam for compensating the effects of temperature and light source variations on the system signals. A device calculates signal ratios and stores the ratios so that the signal ratios of subsequent colored liquids can be converted into colorant concentrations from a look-up table or through calculations using a signal ratio/colorant concentration.

Abstract: The present invention relates to a high-sensitivity defect inspection method, apparatus, and system adapted for the fine-structuring of patterns; wherein, in addition to a cleaning tank which chemically cleans a sample and rinses the sample, a defect inspection apparatus having a liquid-immersion element by which the interspace between the sample and the objective lens of an optical system is filled with a liquid, and a drying tank which dries the sample, the invention uses liquid-immersion transfer means from said cleaning tank through said liquid-immersion means of said defect inspection apparatus to said drying tank so that the sample is transferred in a liquid-immersed state from said cleaning tank to said liquid-immersion means.