A method of generating laser pulses (1) includes: creating a circulating light field in resonator device (11) having resonator length L and an intra-cavity dispersion and configured for supporting light field resonator modes, and generating a pulse train of laser pulses (1) by a mode-locking mechanism. Laser pulses (1) are generated with a repetition frequency and provide a frequency comb with carrier frequency .sub.o and comb modes in frequency space. The intra-cavity dispersion is selected such that round trip phases have a dependency on frequency according to $\left(\right)=m\left(\sqrt{1+4\frac{-{}_0}{m{}_r}}-1\right)+\frac{L}{c}{}_0$
wherein m is an integer providing effective repetition rate (m.sub.r) in combination with mode spacing .sub.r at optical carrier frequency (.sub.o), and the mode-locking mechanism provides a coupling of the resonator modes whereby frequency difference (n=.sub.n+1.sub.n) between neighboring mode frequencie

An assembly (14) for analyzing a sample (15) includes a detector assembly (18); a tunable laser assembly (10); and (iii) a laser controller (10F). The detector assembly (18) has a linear response range (232) with an upper bound (232A) and a lower bound (232B). The tunable laser assembly (10) is tunable over a tunable range, and includes a gain medium (10B) that generates an illumination beam (12) that is directed at the detector assembly (18). The laser controller (10F) dynamically adjusts a laser drive to the gain medium (10B) so that the illumination beam (12) has a substantially constant optical power at the detector assembly (18) while the tunable laser assembly (10) is tuned over at least a portion of the tunable range.

The present invention relates to an analysis apparatus adapted to analyze a measurement target component contained in a sample by irradiating a measurement cell into which the sample is introduced with pulse-oscillated light, whereby suppressing reduction in wavelength resolution without shortening the pulse width. The analysis apparatus includes multiple light sources adapted to produce pulse oscillations, a light detector adapted to detect light emitted from the light source and transmitted through the measurement cell, and a signal separation part adapted to separate, from a light intensity signal obtained by the light detector, signals corresponding to a part of pulses from the light sources.

The invention relates to a method of determining the concentration of a gas component comprising the steps: generating and guiding a light beam having a wavelength variable in a wavelength range through a measurement volume in which the gas component having an absorption in the wavelength range is present; tuning the wavelength range; detecting the intensity of the light beam after passage through the measurement volume; storage of measurement points during the tuning that respectively consist of a point in time and an associated intensity value, to obtain a direct absorption line; generating an artificial measurement curve from the stored measurement points by shifting the measurement points on the time axis; wherein the shift takes place so that an artificial modulation results in the wavelength time extent; and evaluating the artificial measurement curve in accordance with the method of the wavelength modulation spectroscopy and determining a first concentration value therefrom.

A terahertz spectrometer includes: a terahertz-wave emitter and a terahertz receiver elements. The terahertz wave generated by means of generating beat frequency corresponding to the difference between two rapidly tunable continuous wave lasers. Having a difference in time between the interrogating signal and the reference signal at the receiver end side, which corresponds to intermediate frequency (IF), not centered around the baseband, i.e. zero Hertz. The offset step size of the intermediate frequency from zero Hertz is linearly correlated to the position of the interrogated object position.

A method of generating laser pulses (1) includes: creating a circulating light field in resonator device (11) having resonator length L and an intra-cavity dispersion and configured for supporting light field resonator modes, and generating a pulse train of laser pulses (1) by a mode-locking mechanism. Laser pulses (1) are generated with a repetition frequency and provide a frequency comb with carrier frequency .sub.o and comb modes in frequency space. The intra-cavity dispersion is selected such that round trip phases have a dependency on frequency according to

[00001]$\left(\right)=.Math..Math.m\left(\sqrt{1+4.Math..Math.\frac{-{}_0}{m.Math..Math.{}_r}}-1\right)+\frac{L}{c}.Math.{}_0$

wherein m is an integer providing effective repetition rate (m.sub.r) in combination with mode spacing .sub.r at optical carrier frequency (.sub.o), and the mode-locking mechanism provides a coupling of the resonator modes whereby frequency difference (n=.sub.n+1.sub.n) between neighboring mode frequencies (.sub.n, .sub.n+1) is a linear function of mode frequency number n. Furthermore, a spectroscopy method for investigating a sample, a laser pulse source apparatus and a spectroscopy apparatus are described.

Methods and apparatuses of generating and processing a real-time time-domain cavity ringdown spectroscopy (CRDS) signal from absorbing species in an optical detection system having an optical ringdown cavity using off-axis paths are provided. At least one modulated light signal is generated using one or more light sources, each modulated at specified modulation frequency. Each modulated signal has harmonic frequency components and is input off-axis relative to the cavity's optical axis. The cavity contains mirrors arranged in a predetermined configuration. The optical axis is defined by a path passing through centers of mirrors. The modulated light signal is resonated off axis without astigmatic optical elements to produce CRDS signal and passes at least twice through cavity and across the mirrors without interfering with itself. An overall path length through cavity is greater than path length of optical axis. A photodetector detects the CRDS signal, which is demodulated dependent upon selected harmonics.

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.

Detector data representative of an intensity of light that impinges on a detector after being emitted from a light source and passing through a gas over a path length can be analyzed using a first analysis method to obtain a first calculation of an analyte concentration in the volume of gas and a second analysis method to obtain a second calculation of the analyte concentration. The second calculation can be promoted as the analyte concentration upon determining that the analyte concentration is out of a first target range for the first analysis method.

This invention can be embodied in a mobile device for food identification and quantification with both a spectroscopic sensor and a camera. It can be a handheld food scanner, food probe, smart food utensil, utensil attachment, removable component of a smart watch or wrist band, phone component, or phone accessory. It can provide information on types and quantities of food (and nutrients, chemicals, and microorganisms in that food). It can be wirelessly linked with a wearable device to comprise a system for monitoring and modifying a person's food consumption habits.