A birefringence measurement device includes a light flux generator for generating light flux, a light flux irradiator for irradiating a measurement target with the light flux in a predetermined polarization state, an imaging optical system for forming an image from light flux transmitted through the measurement target, a polarization/diffraction grating positioned within the imaging optical system, an image pickup for generating a light-dark signal related to brightness of the image, and an output for outputting information regarding a phase difference for the light flux. The phase difference resulting from the transmission through the measurement target is determined on the basis of the light-dark signal. The image pickup generates the light-dark signal for the image based on at least one beam of diffracted light from among a plurality of beams of diffracted light produced by the grating. A two-dimensional distribution of birefringence is obtained in real time without a rotating mechanism.

A method of authenticating a polymer film comprises measuring the thickness of a layer therein by white light interferometry and/or measuring the birefringence of a layer therein. The method, and devices to carry out the method, may be used in security applications, for example to test for counterfeit bank notes.

A method of authenticating a polymer film comprises measuring the thickness of a layer therein by white light interferometry and/or measuring the birefringence of a layer therein. The method, and devices to carry out the method, may be used in security applications, for example to test for counterfeit bank notes.

A sensor having a substrate is provided in which structures are disposed on a surface of the substrate. The structures can be, e.g., nanostructures. Polarized light is directed toward the sensor, and birefringence of the structures with respect to the light is measured. Target particles that interact with the structures are detected based on changes in the measured birefringence.

A sensor having a substrate is provided in which structures are disposed on a surface of the substrate. The structures can be, e.g., nanostructures. Polarized light is directed toward the sensor, and birefringence of the structures with respect to the light is measured. Target particles that interact with the structures are detected based on changes in the measured birefringence.

An eye tracking and gaze fixation detection system, includes an electronically scannable optical illumination system emits polarized near-infrared (NIR) light to a retina in an eye of a subject; an optical detection system arranged in an optical path of the NIR light after being reflected from the retina of the eye of the subject, the optical detection system providing a detection signal; and a signal processing system communicates with the optical detection system to receive the detection signal, wherein the optical illumination system emits the polarized NIR light to illuminate at least a portion of a scanning path, wherein the scanning path is a spatially closed loop across a portion of the retina in the eye of the subject that repeats periodically over time, and wherein the signal processing system is configured to determine at least one of a gaze direction and a gaze fixation based on the detection signal.

An eye tracking and gaze fixation detection system, includes an electronically scannable optical illumination system emits polarized near-infrared (NIR) light to a retina in an eye of a subject; an optical detection system arranged in an optical path of the NIR light after being reflected from the retina of the eye of the subject, the optical detection system providing a detection signal; and a signal processing system communicates with the optical detection system to receive the detection signal, wherein the optical illumination system emits the polarized NIR light to illuminate at least a portion of a scanning path, wherein the scanning path is a spatially closed loop across a portion of the retina in the eye of the subject that repeats periodically over time, and wherein the signal processing system is configured to determine at least one of a gaze direction and a gaze fixation based on the detection signal.

In an embodiment, a distortion-measuring apparatus for measuring a distortion distribution of an entire vitreous silica crucible in a non-destructive way includes: a light source 11; a first polarizer 12 and a first quarter-wave plate 13 disposed between the light source 11 and an outer surface of a vitreous silica crucible wall; a camera 14 disposed inside of a vitreous silica crucible 1; a camera control mechanism 15 configured to control a photographing direction of the camera 14; a second polarizer 16 and a second quarter-wave plate 17 disposed between the camera 14 and an inner surface of the vitreous silica crucible wall. An optical axis of the second quarter-wave plate 17 inclines 90 degrees with respect to the first quarter-wave plate 13.

In an embodiment, a distortion-measuring apparatus for measuring a distortion distribution of an entire vitreous silica crucible in a non-destructive way includes: a light source 11; a first polarizer 12 and a first quarter-wave plate 13 disposed between the light source 11 and an outer surface of a vitreous silica crucible wall; a camera 14 disposed inside of a vitreous silica crucible 1; a camera control mechanism 15 configured to control a photographing direction of the camera 14; a second polarizer 16 and a second quarter-wave plate 17 disposed between the camera 14 and an inner surface of the vitreous silica crucible wall. An optical axis of the second quarter-wave plate 17 inclines 90 degrees with respect to the first quarter-wave plate 13.

Synthetic quartz glass substrates are prepared by furnishing a synthetic quartz glass block, coating two opposed surfaces of the glass block with a liquid having a transmittance of at least 99.0%/mm at a birefringence measuring wavelength, measuring a birefringence of the glass block by directing light thereacross, determining a slice thickness on the basis of the birefringence measurement and the dimensions of the substrate, and slicing the glass block at the determined slice thickness.