A system for inspecting a slab of material may include a polarization maintaining single mode optical-fiber, a linearly polarized broadband light-source configured to emit a polarized-light over the optical fiber, a beam-assembly configured to receive the light over the optical fiber and direct the light toward a slab of material; a polarization-rotator for controlling polarization of the light directed to the slab of material from the beam-assembly; a computer-controlled etalon filter configured to receive the light over the optical fiber, filter the light, and direct the light over the optical fiber; and a computer-controlled spectrometer configured to receive the light over the optical fiber after the light has been filtered by the etalon filter and after the light has been reflected from or transmitted through the slab of material and spectrally analyze the light.

A wear amount measuring apparatus includes a light source, a light transmission unit, a first and a second irradiation unit, a spectroscope and an analysis unit. The light transmission unit splits a low-coherence light from the light source into a first and a second low-coherence light. The first and the second irradiation units irradiate the first and the second low-coherence light to the component to receive reflected lights from the component. The light transmission unit transmits the reflected lights received by the first irradiation unit and the second irradiation unit to the spectroscope. The spectroscope configured to detect intensity distribution of the reflected lights from the first and the second irradiation unit. The analysis unit calculates a thickness difference between a thickness of the component at the first measuring point and that at the second measuring point by performing Fourier transform on the intensity distribution.

A system for inspecting a slab of material may include a polarization maintaining single mode optical-fiber, a linearly polarized broadband light-source configured to emit a polarized-light over the optical fiber, a beam-assembly configured to receive the light over the optical fiber and direct the light toward a slab of material; a polarization-rotator for controlling polarization of the light directed to the slab of material from the beam-assembly; a computer-controlled etalon filter configured to receive the light over the optical fiber, filter the light, and direct the light over the optical fiber; and a computer-controlled spectrometer configured to receive the light over the optical fiber after the light has been filtered by the etalon filter and after the light has been reflected from or transmitted through the slab of material and spectrally analyze the light.

An OCT system includes a light source configured to generate an optical beam, a Fizeau-type interferometer configured to receive the optical beam and produce an interference pattern, a detector configured to receive the interference pattern and produce an image signal, and a processing circuit including a processor and a memory, the memory being structured to store instructions that are executable by the processor to cause the processor to receive the image signal from the detector and generate an OCT image based on the image signal. The Fizeau-type interferometer includes a scanning element configured to receive the optical beam and direct the optical beam in a plurality of directions towards a sample and a reflective element configured to divide the directed optical beam into a reference beam and a sample beam that reflects off of a surface of a sample.

The invention provides a method and apparatus for applying spatial filtering the optical beam of a free space optical coherence tomography (OCT) system substantially without problematic reflections back to the optical source. The invention teaches spatially filtering the reference beam of the OCT system which is typically designed to provide isolation of the optical source from undesirable optical feed-back, thereby achieving spatial filtering without generating undesirable reflections back to the optical source. Various embodiments are taught.

Disclosed is a three-dimensional shape measuring apparatus using a diffraction grating, comprising: a light splitter installed in a traveling direction of a light generated from a light source unit and configured to reflect a portion of the light along a first path and transmit a portion of the light along a second path; an image sensor unit configured to receive a light traveling along the first path and reflected from a measurement target having at least one hole, and measure the shape of the measurement target; and a diffraction grating disposed on at least one light path among a light path between the light source unit and the light splitter, a light path between the measurement target and the light splitter, and a light path between the measurement target and the image sensor unit.

A system for inspecting a slab of material may include a polarization maintaining single mode optical-fiber, a linearly polarized broadband light-source configured to emit a polarized-light over the optical fiber, a beam-assembly configured to receive the light over the optical fiber and direct the light toward a slab of material; a polarization-rotator for controlling polarization of the light directed to the slab of material from the beam-assembly; a computer-controlled etalon filter configured to receive the light over the optical fiber, filter the light, and direct the light over the optical fiber; and a computer-controlled spectrometer configured to receive the light over the optical fiber after the light has been filtered by the etalon filter and after the light has been reflected from or transmitted through the slab of material and spectrally analyze the light.

A system for inspecting a slab of material may include a polarization maintaining single mode optical-fiber, a linearly polarized broadband light-source configured to emit a polarized-light over the optical fiber, a beam-assembly configured to receive the light over the optical fiber and direct the light toward a slab of material; a polarization-rotator for controlling polarization of the light directed to the slab of material from the beam-assembly; a computer-controlled etalon filter configured to receive the light over the optical fiber, filter the light, and direct the light over the optical fiber; and a computer-controlled spectrometer configured to receive the light over the optical fiber after the light has been filtered by the etalon filter and after the light has been reflected from or transmitted through the slab of material and spectrally analyze the light.

The invention provides a method and apparatus for applying spatial filtering the optical beam of a free space optical coherence tomography (OCT) system substantially without problematic reflections back to the optical source. The invention teaches spatially filtering the reference beam of the OCT system which is typically designed to provide isolation of the optical source from undesirable optical feed-back, thereby achieving spatial filtering without generating undesirable reflections back to the optical source. Various embodiments are taught.

A sample may be illuminated in such a way that light passes through the sample, reflects from a set of reflectors, passes through the sample again and travels to a light sensor. The reflectors may be staggered in depth beneath the sample, each reflector being at a different depth. Light reflecting from each reflector, respectively, may arrive at the light sensor during a different time interval than that in which light reflecting from other reflectors arrivesor may have a different phase than that of light reflecting from the other reflectors. The light sensor may separately measure light reflecting from each reflector, respectively. The reflectors may be extremely small, and the separate reflections from the different reflectors may be combined in a super-resolved image. The super-resolved image may have a spatial resolution that is better than that indicated by the diffraction limit.