A wavelength monitor includes: a wavelength tunable laser (1) having a plurality of emitting ports (10, 11), from which laser beams of the same wavelength are emitted; collimating lenses (20, 21) , which are configured to collimate the laser beams emitted from the emitting ports (10, 11) to emit the collimated laser beams; an optical filter (4) having a periodic transmittance with respect to a frequency, on which the laser beams emitted from the collimating lenses (20, 21) are incident; and an optical detector (5) configured to receive the laser beams that have passed through the optical filter (4) to detect light intensities of the laser beams. In the wavelength monitor, the collimating lenses (20, 21) and the optical filter (4) are disposed so that the laser beams are incident on the optical filter (4) while a condition expressed as Equation (1) is satisfied.

A wavelength monitor includes: a wavelength tunable laser (1) having a plurality of emitting ports (10, 11), from which laser beams of the same wavelength are emitted; collimating lenses (20, 21), which are configured to collimate the laser beams emitted from the emitting ports (10, 11) to emit the collimated laser beams; an optical filter (4) having a periodic transmittance with respect to a frequency, on which the laser beams emitted from the collimating lenses (20, 21) are incident; and an optical detector (5) configured to receive the laser beams that have passed through the optical filter (4) to detect light intensities of the laser beams. In the wavelength monitor, the collimating lenses (20, 21) and the optical filter (4) are disposed so that the laser beams are incident on the optical filter (4) while a condition expressed as Equation (1) is satisfied.

A cylindrical package includes a cylindrical housing; a pedestal at a bottom of a cylindrical space surrounded by the cylindrical housing; an optical splitter in the cylindrical space and over the pedestal; a first photodetector in the cylindrical space and over the pedestal, wherein the first photodetector is configured to be optically coupled to the optical splitter; and a second photodetector in the cylindrical space and over the pedestal, wherein the second photodetector is configured to be optically coupled to the optical splitter.

According to the present disclosure, there is provided a device (2) and a method for measuring a wavelength for a laser device. The device (2) for measuring a wavelength for a laser device includes: a first optical path assembly and a second optical path assembly. The first optical path assembly and the second optical path assembly constitute a laser wavelength measurement optical path. The second optical path assembly includes: an FP etalon assembly (11) and an optical classifier (13). The homogenized laser beam passes through the FP etalon assembly (11) to generate an interference fringe. The optical classifier (13) is arranged after the FP etalon assembly (11) in the laser wavelength measurement optical path, and configured to deflect the laser beam passing through the FP etalon assembly (11).

An optical system comprising a randomizer that has a plurality of randomly positioned scatterers for scattering and thereby randomizing light to generate a speckle pattern and a detector for detecting the speckle pattern to determine at least one property of the light and/or change in at least one property of the light.

An observation apparatus (100) includes an observing optical system (101) capable of obtaining an image of a measurement target present in a gap included in a device (1). One end of the gap included in the device (1) is wider than the other end thereof, and upon light beam irradiation to the device (1), an interference fringe appears in the gap. The observing optical system (101) irradiates the gap included in the device (1) with a plurality of light beams having different wavelengths to cause a plurality of interference fringes to appear in the gap. Then the observing optical system (101) obtains an image of the plurality of interference fringes.

A process for characterizing an optical source including a fixed cavity having a free spectral range, the process including: generating a first radiation; receiving at least a portion of this first radiation by at least one sensor; measuring a signal by each sensor and for each scanned state of the source; on the basis of the signals measured, and for each scanned state of the source, calculating a first data item which represents the wavelength of the first radiation, the calculation including, for each scanned state of the source, a selection of a selected value of the first data item from a plurality of possible values, the selection including the elimination of the values of the first data item which do not correspond to a modulo constant of the free spectral range of the fixed cavity expressed according to the units of the first data item.

A wavelength measuring device configured to detect a wavelength of ultraviolet laser light outputted from a laser resonator with at least one etalon, the wavelength measuring device includes: a first housing having an interior space being sealed and accommodating the etalon, an input window through which the ultraviolet laser light enters to the first housing, the input window being provided at a first opening of the first housing, a first sealing member configured to seal a gap between a rim part of the input window and a circumferential portion of the first opening, a shielding film provided between the rim part of the input window and the first sealing member and configured to shield the first sealing member from the ultraviolet laser light coming from the input window, and a diffusing element provided outside of the first housing and configured to diffuse the ultraviolet laser light before being incident on the input window.

An optical system comprising a randomizer that has a plurality of randomly positioned scatterers for scattering and thereby randomizing light to generate a speckle pattern and a detector for detecting the speckle pattern to determine at least one property of the light and/or change in at least one property of the light.

An optical system comprising a randomizer that has a plurality of randomly positioned scatterers for scattering and thereby randomizing light to generate a speckle pattern and a detector for detecting the speckle pattern to determine at least one property of the light and/or change in at least one property of the light.