The purpose of the present invention is to provide a displacement detecting device capable of decreasing a measurement error, even when a diffraction grating is inclined or displaced to a direction other than a measuring direction. The displacement detecting device 1 comprising: a light source 2 for emitting light; a polarized beam splitter 7; a diffraction grating 11; a prism unit 16A (16 to 19) for shifting light path; lenses 14 and 20 for correcting light path; and an interfered light receiving unit 22A (22 to 30). The prism unit 16A for shifting light path shifts first diffracted light to a direction vertical to the measuring direction. The lenses 14 and 20 for correcting light path is arranged on a symmetrical axis of light paths and corrects light path when the diffraction grating 11 is inclined or moved to a normal direction of a grating surface.

An optical sensing device for a wheel set is provided. The optical sensing device comprises a first grating, a second grating, an elastic object and two optical sensors. The first grating is set in a first wheel of the wheel set. The second grating is set in a second wheel of the wheel set. The elastic object is connected between the first wheel and the second wheel, and is adapted to sustain a force applied when an angle difference is formed by a rotation of the second wheel with respect to the first wheel. The two optical sensors are set in a power module of the wheel set and provided respectively in correspondence to the first and the second gratings. The two optical sensors receive two optical signals reflected by the first and the second gratings, and the two optical sensors are used to calculate the angle difference.

A beam-shaping optical system suitable for use with optical coherence tomography having a beam-shaping insert having a polymeric material, the beam-shaping insert integrally defining a beam-shaping element. The beam-shaping element has a reflective element positioned on a curved surface. A light source generates an electromagnetic beam. An optical fiber having a core and a cladding, the optical fiber having first end optically coupled with the light source and a fiber end. The fiber end is configured to emit the electromagnetic beam toward the beam-shaping element. The reflective element has a reflectivity greater than about 98% for both a first wavelength band of the electromagnetic beam and a second wavelength band of the electromagnetic beam.

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.

An optical position-measuring device includes a scale and a scanning reticle, whose relative position is determinable in three linearly independent spatial directions using interfering light beams. A splitter grating is disposed on the scanning reticle and adapted to split light into sub-beams of different diffraction orders. An optical grating is disposed on the scale and adapted to further split the sub-beams and to recombine them after they have been reflected back from the scanning reticle. Grating fields configured as phase gratings are disposed on a side of the scanning reticle that faces the scale. The grating fields act as diffractive optics that influence the further split sub-beams. The grating fields have different step heights. An output grating is disposed on the scanning reticle and adapted to output, as interfering sub-beams, light that has been multiply reflected between the scale and the scanning reticle.

An electronic wafer inspecting method includes: rotating the wavelength transparent wafer, emitting, from a light source coupled with an interferometric device, two light beams, to form, a measurement volume and having a vaiable inter-fringe distance within the volume, a time signature of a defect intersecting the measurement volume depending on an inter-fringe distance where the defect intersects the volume, the device and the wafer arranged so that the measurement volume extends into a wafer region, collecting the light scattered by the wafer region, emitting a signal representing the variation in the intensity of the collected light per time, detecting in the signal, a frequency of the intensity, the frequency being the time of the passge of a defect through the measurement volume, determining, based on the value of the inter-fringe distance at the location where the defect passes, the position of the defect.

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.

By utilizing the fact that the observation object has a three-dimensional shape and the boundary surface can be regarded as a plane surface, phase or intensity distribution is applied into a luminous flux of reference light, thereby selectively attenuating the influence of the reflected light from the boundary surface so as to obtain a high-quality OCT image.

A beam-shaping optical system suitable for use with optical coherence tomography includes a sheath defining a central cavity having an inner wall, an optical fiber positioned within a ferrule, the ferrule configured to mate with the inner wall of the sheath, and a beam-shaping insert positioned within the sheath and configured to mate with the inner surface of the sheath. The beam-shaping insert defines a beam-shaping element. The optical fiber is configured to emit an electromagnetic beam toward the beam-shaping element and the beam-shaping element is configured to reflect the electromagnetic beam externally to the beam-shaping insert.

A beam-shaping optical system suitable for use with optical coherence tomography including a sheath defining a central cavity, a beam-shaping insert defining a beam-shaping element positioned within the central cavity, and an optical fiber having a core and a cladding. The optical fiber defines an angularly prepared fiber end configured to emit an electromagnetic beam toward the beam-shaping element with the core of the optical fiber locally expanded at the fiber end.