A gas cell (1) for the spectroscopic, in particular absorption spectroscopic, analysis of a gas, in which the gas is exposed to an incident beam of rays (S) of electromagnetic radiation and a beam of rays (S.sub.A) of electromagnetic radiation exiting the gas is detected to form a measurement signal, wherein the gas cell (1) comprises a body (10) formed by a porous, electromagnetic radiation-scattering material, an in-coupling device (20) for coupling the incident beam of rays (S) into the gas cell (1) and an out-coupling device (30) for coupling the exiting beam of rays (S.sub.A) out of the gas cell (1), wherein, according to the invention, the gas cell is further developed according to the invention by forming a material-free cavity (12) in the body (10), which is surrounded by an inner surface (14) running within the material and is both diffusely reflecting and transmitting the electromagnetic radiation.

A dual-comb spectrometer comprising two lasers outputting respective frequency combs having a frequency offset between their intermode beat frequencies. One laser acts as a master and the other as a follower. Although the master laser is driven nominally with a DC drive signal, the current on its drive input line nevertheless oscillates with an AC component that follows the beating of the intermode comb lines lasing in the driven master laser. This effect is exploited by tapping off this AC component and mixing it with a reference frequency to provide the required frequency offset, the mixed signal then being supplied to the follower laser as the AC component of its drive signal. The respective frequency combs in the optical domain are thus phase-locked relative to each other in one degree of freedom, so that the electrical signals obtained by multi-heterodyning the two optical signals are frequency stabilized.

Disclosed is an optical detection system for detecting a decomposition product of a high-voltage device, including: a measurement gas chamber and a measurement host. The measurement gas chamber is disposed on the high-voltage device and is in communication with a gas chamber of the high-voltage device, a collimator and a reflector are disposed on two sides of the measurement gas chamber respectively, and the measurement host is connected to the collimator. The collimator is used for emitting measurement laser to the measurement gas chamber according to a laser signal sent by the measurement host, and receiving reflected laser from the reflector and transmitting the reflected laser to the measurement host. In the present invention, data collection and backhaul between a measurement host and a measurement gas chamber are implemented through a laser signal, thus avoiding electromagnetic interference and improving the safety of measurement for a high-voltage device.

A device that uses two intensity modulated frequency combs to measure distances with high precision and high data acquisition rate without any moving parts and without length ambiguity that is inherent conventional ranging based on two frequency combs. A modulation signal having a repetition rate identical to the repetition rate difference between the two combs is used to do a direct time-of-flight length measurement, hence avoiding the given length ambiguity while harvesting the increased precision of the dual-comb approach.

A dual-comb spectrometer comprising two lasers outputting respective frequency combs having a frequency offset between their intermode beat frequencies. One laser acts as a master and the other as a follower. Although the master laser is driven nominally with a DC drive signal, the current on its drive input line nevertheless oscillates with an AC component that follows the beating of the intermode comb lines lasing in the driven master laser. This effect is exploited by tapping off this AC component and mixing it with a reference frequency to provide the required frequency offset, the mixed signal then being supplied to the follower laser as the AC component of its drive signal. The respective frequency combs in the optical domain are thus phase-locked relative to each other in one degree of freedom, so that the electrical signals obtained by multi-heterodyning the two optical signals are frequency stabilized.

Pulsed fluorescence imaging in a light deficient environment is disclosed. A system includes an emitter for emitting pulses of electromagnetic radiation and an image sensor comprising a pixel array for sensing reflected electromagnetic radiation. The system includes a controller configured to synchronize timing of the emitter and the image sensor. The system is such that at least a portion of the pulses of electromagnetic radiation emitted by the emitter comprises electromagnetic radiation having a wavelength from about 795 nm to about 815 nm.

A frequency-measurement method uses a dual frequency-comb spectrometer as an optical wavemeter to measure the frequency of a reference laser that is used to frequency-stabilize the spectrometer. The method includes measuring a walking rate of center bursts in a sequence of interferograms recorded by the spectrometer, determining a number of teeth in each of a plurality of Nyquist windows formed by the dual frequency-comb spectrometer, and determining a Nyquist number of the one Nyquist window covering the laser frequency. The reference laser frequency can then be determined from the number of teeth in each Nyquist window, the Nyquist number, and the comb spacing of either one of the two frequency combs of the dual frequency-comb spectrometer. The reference laser frequency does not need to be measured with a separate wavemeter, or calibrated with respect to a known atomic or molecular transition.

Disclosed herein are a method for diagnosing a disease of a body tissue by using LIBS (Laser-Induced Breakdown Spectroscopy) comprising: preparing a laser device including: a laser projection module, outputting the laser to a suspicious region of the body tissue, a light receiving module, receiving a plurality of light, a spectrum measurement module, and a guide unit; and projecting the laser to generate plasma by inducing tissue ablation in the suspicious region; wherein the laser projected to the suspicious region has a target area, and wherein the target area has smaller size than the suspicious region such that the target area is located inside the suspicious region.

Pulsed fluorescence imaging in a light deficient environment is disclosed. A system includes an emitter for emitting pulses of electromagnetic radiation and an image sensor comprising a pixel array for sensing reflected electromagnetic radiation. The system includes a controller configured to synchronize timing of the emitter and the image sensor. The system is such that at least a portion of the pulses of electromagnetic radiation emitted by the emitter comprises electromagnetic radiation having a wavelength from about 770 nm to about 790 nm or from about 795 nm to about 815 nm.

Systems and methods are disclosed to determine the concentration of a species within a sample. An example method may include collecting optical loss data over a range of frequencies from the sample using a spectroscopy system; placing the optical loss data into a plurality of bins, each bin having a defined frequency width; determining an average optical loss data value for the optical loss values within each bin that have an optical loss value less than a threshold value; removing the optical loss data within each bin having a value outside a tolerance range bounding the average optical loss data value for the respective bin; fitting a spectral curve to the remaining optical loss data; and determining the concentration of the species within the sample based on the spectral curve.