A measurement system for use in measuring parameters of a patterned sample, the system including a broadband light source, an optical system configured as an interferometric system, a detection unit, and a control unit, where the interferometric system defines illumination and detection channels having a sample arm and a reference arm having a reference reflector, and is configured for inducing an optical path difference between the sample and reference arms, the detection unit for detecting a combined light beam formed by a light beam reflected from the reflector and a light beam propagating from a sample's support, and generating measured data indicative of spectral interference pattern formed by spectral interference signatures, and the control unit for receiving the measured data and applying a model-based processing to the spectral interference pattern for determining one or more parameters of the pattern in the sample.

The present invention provides a surface emitting laser the wavelength-tunable band of which is wide. The wavelength-tunable surface emitting laser includes a first reflector (101), an active layer (103) disposed on the first reflector (101), a beam portion (110) disposed over the active layer (103) with an air gap therebetween, and a second reflector (120) disposed on the beam portion (110). The second reflector (120) has a distributed Bragg reflector consisting of a stack of dielectric layers. The beam portion (110) has a distributed Bragg reflector consisting of a stack of conductive semiconductor layers.

Provided is a position detection method including splitting detection light into first and second light, the first light being incident on a returning optical path, a portion of the first light being transmitted through a beam splitter and a remaining portion of the first light being reflected by the beam splitter to reach the beam splitter through a movable mirror every time the first light reaches the beam splitter through the movable mirror, combining the first light transmitted though the beam splitter and the second light to generate multiple interference light, extracting a second interference light signal having a wavelength of 1/p (p is a natural number) of a wavelength of detection light from a first interference light signal of the multiple interference light, and calculating a position of the movable portion in a predetermined direction based on the second interference light signal.

Apparatus, systems, and methods of operating a fiber laser having polarization-preserving fibers can be applied as a sensor to detect a physical quantity. In various embodiments, polarization-preserving fibers can provide a laser cavity having an interferometer disposed in the laser cavity. In various embodiments, a fiber optical parametric oscillator can include an interferometer disposed in the cavity of the optical parametric oscillator. Additional apparatus, systems, and methods are disclosed.

An interferometer (10) is provided that has a stage (28) configured to have a linear motion path. A first retroreflector (18) and a second retroreflector (24) are fixedly coupled to the stage (28). A tube (32) is provided, and the stage (28) is configured to reciprocate about the tube (32). A beamsplitter (14) and a 45 mirror (16) are disposed in the tube (32). A detector (22) is configured to detect light passing through the beamsplitter (14), and the beamsplitter (14) is configured to split an incident light beam into a transmitted beam (15) and a reflected beam (17), wherein the transmitted beam (15) passes to the second retroreflector (24) and the reflected beam (17) passes to the first retroreflector (18). The transmitted beam (15) and a reflected beam (17) are focused on the detector (22).

An interferometer (10) is provided that has a stage (28) configured to have a linear motion path. A first retroreflector (18) and a second retroreflector (24) are fixedly coupled to the stage (28). A tube (32) is provided, and the stage (28) is configured to reciprocate about the tube (32). A beamsplitter (14) and a 45 mirror (16) are disposed in the tube (32). A detector (22) is configured to detect light passing through the beamsplitter (14), and the beamsplitter (14) is configured to split an incident light beam into a transmitted beam (15) and a reflected beam (17), wherein the transmitted beam (15) passes to the second retroreflector (24) and the reflected beam (17) passes to the first retroreflector (18). The transmitted beam (15) and a reflected beam (17) are focused on the detector (22).

An atomic interferometer and methods for measuring phase shifts in interference fringes using the same. The atomic interferometer has a laser beam traversing an ensemble of atoms along a first path and an optical components train with at least one alignment-insensitive beam routing element configured to reflect the laser beam along a second path that is anti-parallel with respect to the first laser beam path. Any excursion from parallelism of the second beam path with respect to the first is rigorously independent of variation of the first laser beam path in yaw parallel to an underlying plane.

An example embodiment may include an interferometer. The interferometer may include a multimode waveguide with an input waveguide optically coupled to a first side of the multimode waveguide, for feeding a light signal to the multimode waveguide. The interferometer may also include a first waveguide at one end optically coupled to a second side of the multimode waveguide, and at the other end terminated by a first waveguide mirror. The interferometer may also include a second waveguide at one end optically coupled to the second side of the multimode waveguide and at the other end terminated by a second waveguide mirror. The multimode waveguide may be adapted to distribute the light signal towards the first and second waveguide mirror via the first waveguide and via the second waveguide.

The present invention provides an interferometer and the like, that is capable of ensuring the speed stability of the movable mirror while achieving the speed up of the reciprocal movement of the moving mirror and suppressing the increment of the maximum instantaneous thrust force required for the turning back as much as possible. The interferometer includes a moving mirror, a movement mechanism for reciprocating the moving mirror, a movement control part for controlling the movement mechanism and allowing the moving mirror to be reciprocated at a constant speed, and a measurement part for measuring a position of the moving mirror. The movement control part is adapted to receive target position data indicating a target position of the moving mirror, and control the movement mechanism to bring the measurement position of the moving mirror measured by the measurement part close to the target position indicated by the target position data.

An optical system, including one or more coherent light, an optical arrangement, and a detection unit, and respective method are described. The optical arrangement includes optical elements forming at least first and second interferometer loops, each including a reference arm and an interrogating arm and are associated with at least first and second detectors of the detection unit. Light propagating in the interrogating arm is directed at a target object via an output optical element and a reflection of light from said target object is collected by an input optical element. The detection unit is configured to determine data indicative of a relation between signals detected by the at least first and second detectors. One of the first and second interferometer loops includes a first noise generator positioned to affect light propagating in both of the corresponding reference and interrogating arms, thereby affecting coherence of light in the interferometer loops.