Defects are detected using data acquired from an interference channel and a polarization modification channel in an interferometer. The interference objective splits a polarized illumination beam into a reference illumination that is reflected by a reference surface without modification to the polarization, and a sample beam that is reflected by a sample surface, that may modify the polarization. Light from the sample beam with no change in polarization is combined with the reference illumination and directed to the interference channel, which may measure the reflectivity and/or topography of the sample. Light from the sample beam with modified polarization is directed to the polarization modification channel. The intensity of the light detected at the polarization modification channel may be used, along with the reflectivity and topography data to identify defects or other characteristics of the sample.

A fluorescent image analyzer stores a reference fluorescent-sample image and a subject fluorescent-sample image. The reference fluorescent-sample image is an image obtained by illuminating a reference fluorescent sample about which relation of in-plane fluorescence intensities is known with linearly polarized light and capturing a first specific polarization component of fluorescence from the reference fluorescent sample. The subject fluorescent-sample image is an image obtained by illuminating a subject fluorescent sample with linearly polarized light and capturing a second specific polarization component of fluorescence from the subject fluorescent sample. The fluorescent image analyzer is configured to determine correction coefficients to correct non-uniformity in measurement of light intensities among pixels of a captured image based on the reference fluorescent-sample image, and correct light intensities of the pixels of the subject fluorescent-sample image based on the correction coefficients.

A scan mirror reflectivity calibration device is provided for monitoring and calibration of a rotating two-sided scan mirror. The scan mirror reflectivity calibration device can comprise at least one light source assembly operable to direct light onto a back side of a rotating two-sided scan mirror. The at least one light source assembly can be mounted outside a swept volume of the rotating two-sided scan mirror. The scan mirror reflectivity calibration device further comprises at least one detector assembly operable to detect light that is emitted from the at least one light source assembly and is reflected off of the back side of the rotating two-sided scan mirror. The at least one detector assembly can be mounted outside the swept volume of the rotating two-sided scan mirror.

A micro-resonator and fiber taper based sensing system, which uses mode splitting or frequency shift methods and polarization measurements for particle sensing.

A method of detecting porosity at and near a composite surface is disclosed, including projecting polarized light on a surface of a composite component and filtering out light reflected off of the surface. The method further includes imaging light scattered from inhomogeneities in the composite component, and generating a map of absence of composite material near the composite surface based on scatter intensity detected in the imaging step.

The present invention provides a sensor combining a dust sensor and a gas sensor, comprising a light emitting unit for emitting light, a first light receiving unit for receiving scattered light which is emitted by the light emitting unit and scattered by dust to detect dust concentration, a mirror for changing a path of the emitted light which the light emitting unit emits, and a second light receiving unit for receiving the emitted light the path of which is changed by the mirror to detect gas concentration. An inflow section for introducing air into a detection space inside the sensor is formed in a Y-shaped tube in which a first inlet and a second inlet meet. The inflow section comprises a switch which selects a path through which air flows into the detection space out of the first inlet and the second inlet.

A surface defect measuring apparatus and method by microscopic scattering polarization imaging is provided. The apparatus mainly comprises a laser, a first converging lens, a rotary diffuser, a second converging lens, a diaphragm, a third converging lens, a pinhole, a fourth converging lens, a polarizer, a half-wave plate, a polarizing beam splitter, an X-Y translation stage, a sample, a microscope lens, a quarter-wave plate, a micro-polarizer array, a camera and a computer. The micro-polarizer array is adopted to realize real-time microscopic scattering polarization imaging of the surface defects; a polarization-degree image is calculated to improve the sensitivity for detecting the surface defects of the ultra-smooth element, and the effective detection of the surface defects of a high-reflective coating element is also realized, and the requirement for rapid detection of the surface defects of a meter-scale large-aperture ultra-smooth element can be met.

Provided are a dual coupler device configured to receive lights of different polarization components, a spectrometer including the dual coupler device, and a non-invasive biometric sensor including the spectrometer. The dual coupler device may include, for example, a first coupler layer configured to receive a light of a first polarization component among incident lights. and a second coupler layer configured to receive a light of a second polarization component among the incident lights, wherein a polarization direction of the light of the first polarization component is perpendicular to a polarization direction of the light of the second polarization component. The first coupler layer and the second coupler layer may be spaced apart from each other and extended along a direction in which the light propagates in the first coupler layer and the second coupler layer.

There is set forth herein in one embodiment, a structure including a metallic grating having a grating pattern, the metallic grating including a critical dimension. The metallic grating can output a spectral profile when exposed to electromagnetic radiation, the spectral profile having a feature. The grating pattern can be configured so that a change of the critical dimension produces a shift in a value of the feature of the spectral profile. A method can include propagating input electromagnetic radiation onto a metallic grating having a two dimensional periodic grating pattern and measuring a critical dimension of the metallic grating using output electromagnetic radiation from the metallic grating.

A method and system are presented for use in measuring on patterned samples, aimed at determining asymmetry in the pattern. A set of at least first and second measurements on a patterned region of a sample is performed, where each of the measurements comprises: directing illuminating light onto the patterned region along an illumination channel and collecting light reflected from the illuminated region propagating along a collection channel to be detected, such that detected light from the same patterned region has different polarization states which are different from polarization of the illuminating light, and generating a measured data piece indicative of the light detected in the measurement. Thus, at least first and second measured data pieces are generated for the at least first and second measurements on the same patterned region. The at least first and second measured data pieces are analyzed and output data is generated being indicative of a condition of asymmetry in the patterned region.