A narrow band laser apparatus may include: a laser resonator; a pair of discharge electrodes; a power supply; a first wavelength measurement device configured to output a first measurement result; a second wavelength measurement device configured to output a second measurement result; and a control unit. The control unit calibrates the first measurement result, based on a difference between the second measurement result derived when the control unit controls the power supply to apply a pulsed voltage to the pair of discharge electrodes with a first repetition frequency and the second measurement result derived when the control unit controls the power supply to apply the pulsed voltage to the pair of discharge electrodes with a second repetition frequency, the second repetition frequency being higher than the first repetition frequency.

Disclosed is a method for determining a wavefront gradient, the method involving irradiating a transmission filter unit with a light and measuring the intensity of light transmitted, followed by another irradiating and measuring of the light transmitted, and calculating a spatial contrast K from a difference of the first intensity and the second intensity and also calculating a local wavefront gradient from the K value and a calibration factor c.

The present disclosure provides a dispersion measurement device and method based on a Franson second-order quantum interference technology. The device includes: an energy-time entangled twin-photon source configured to generate a plurality of optical signals, where the optical signals each include a signal photon and an idle photon; a polarization splitter configured to split the signal photon and the idle photon, and enable the signal photon to pass through a to-be-measured dispersive medium, such that a correlation time processing module records, under a width of a coincidence measurement integration window, first time of the idle photon arriving at a first single-photon detector, and second time of the signal photon arriving at a second single-photon detector, and obtains a twin-photon conference time width based on the first time and the second time; and a processing module.

An optical pressure sensor is disclosed having a pressure sensing optical cavity. A temperature sensing optical cavity at the sensing head is used by an interrogator to correct a pressure signal for effects of temperature. The optical cavities may be, for example, Fabry Perot cavities in the sensor head.

An optical pressure sensor is disclosed having a pressure sensing optical cavity. A temperature sensing optical cavity at the sensing head is used by an interrogator to correct a pressure signal for effects of temperature. The optical cavities may be, for example, Fabry Perot cavities in the sensor head.

An optical pressure sensor is disclosed having a pressure sensing optical cavity. A temperature sensing optical cavity at the sensor head is used by an interrogator to correct a pressure signal for effects of temperature. The optical cavities may be, for example, Fabry Perot cavities in the sensor head.

An optical frequency measurement system includes a beam splitter configured to split a light beam into a plurality of measurement beams, including a first measurement beam and a second measurement beam; a first optical frequency measurement subsystem configured to receive the first measurement beam and measure a first frequency of the first measurement beam with a first accuracy range to obtain a first measured frequency that corresponds to a frequency of the light beam; and a second optical frequency measurement subsystem configured to receive the second measurement beam and measure a second frequency of the second measurement beam with a second accuracy range that is narrower than the first accuracy range to obtain a second measured frequency that corresponds to the frequency of the light beam with a higher accuracy than the first measured frequency.

Disclosed is a linear array scanning Brillouin scattering elastic imaging device. In the device, a signal generating system consists of a narrow linewidth continuous wave laser, a half-wave plate, a beam expander, a Y-direction scanning galvanometer, a microlens array, a pinhole array filter, a first plano-convex lens, a polarization beam splitter, a quarter-wave plate and a microscope objective. A signal receiving system consists of a microscope objective, a quarter-wave plate, a polarization beam splitter and an eight-channel optical collimator array. Each channel of an eight-channel spectrometer consists of an optical collimator, a convex lens, a scanning Fabry-Perot interferometer, a photomultiplier tube and an eight-channel photon collection card.

A laser source may include a laser diode, a modulation device, and a feedback device. The modulation device may include an electric power source and may be suitable for modifying a current intensity applied to the laser diode, which may modify an emission frequency of the laser diode. The feedback device may be suitable for modifying a current intensity applied to the laser diode by the electric power source as a function of the electromagnetic radiation emitted by the laser diode.

The present disclosure provides a dispersion measurement device and method based on a Franson second-order quantum interference technology. The device includes: an energy-time entangled twin-photon source configured to generate a plurality of optical signals, where the optical signals each include a signal photon and an idle photon; a polarization splitter configured to split the signal photon and the idle photon, and enable the signal photon to pass through a to-be-measured dispersive medium, such that a correlation time processing module records, under a width of a coincidence measurement integration window, first time of the idle photon arriving at a first single-photon detector, and second time of the signal photon arriving at a second single-photon detector, and obtains a twin-photon conference time width based on the first time and the second time; and a processing module.