A method for characterizing a light beam includes separating the light beam by a separator optic into first and second sub-beams; propagating the first and second sub-beams over first and second optics, respectively, said first and second optics being respectively arranged so that the sub-beams on leaving the optics are separated by a time delay ; recombining the sub-beams so that they spatially interfere and form a two-dimensional interference pattern; measuring the frequency spectrum of at least part of the interference pattern; calculating the Fourier transform in the time domain of at least one spatial point of the frequency spectrum, the Fourier transform in the time domain having a time central peak and first and second time side peaks; calculating the Fourier transform in the frequency domain for one of the side peaks; calculating the spectral amplitude A.sub.R() and the spatial-spectral phase .sub.R(x,y,) for the Fourier transform in the frequency domain.

An interferometric device: includes a separator, for separating a collimated beam (F0) into first (F1) and second (F2) incident beams; at least one transducer; and a transparent optical system, including at least three planar diopters (D1, D2, D3). The the transducer is based on plasmon resonance and in contact with the diopter (D1); the diopter (D2) has a network of nanostructures; the optical system and the separator being configured such that the beam (F1) and the beam (F2) undergo total internal reflection on the diopter (D1) and on the diopter (D3), respectively, prior to interfering on the diopter (D2) by total internal reflection and to forming an interferogram in which the central fringe is located at a convergence point (ZOPD).

Current apparatuses and methods for analysis of spectroscopic optical coherence tomography (SOCT) signals suffer from an inherent tradeoff between time (depth) and frequency (wavelength) resolution. In one non-limiting embodiment, multiple or dual window (DW) apparatuses and methods for reconstructing time-frequency distributions (TFDs) that applies two windows that independently determine the optical and temporal resolution is provided. For example, optical resolution is provided. For example, optical resolution may relate to scattering information about a sample, and temporal resolution may be related to absorption or depth related information. The effectiveness of the apparatuses and methods is demonstrated in simulations and in processing of measured OCT signals that contain fields which vary in time and frequency. The DW technique may yield TFDs that maintain high spectral and temporal resolution and are free from the artifacts and limitations commonly observed with other processing methods.

A spectrometry device wherein light rays emitted from an object face measurement point combine into one parallel light beam by an objective lens, this is divided into a first and second light beam by a phase shifter, and the first and second light beam emit toward a light-receiving face of a photodetector while providing an optical path length difference. A light-shielding plate is arranged on a face optically conjugate the object face respective to the objective lens, and only light passed through translucent portions of the light-shielding plate is directed to the objective lens. A lateral length of each light-shielding plate translucent portion and the interval between two adjacent translucent portions are based on the objective lens focal length, the distance from the phase shifter to the photodetector light-receiving face, a photodetector pixel pitch, a pixel length, and a predetermined wavelength range of the light emitted from the measurement point.

An interferometer including an analysis optical system including a retroreflector configured to reflect analysis light and a first light receiver configured to receive the analysis light and output a first light reception signal, the analysis optical system irradiating a sample with the analysis light and causing the analysis light to interfere; a length measuring optical system including a laser light source configured to output laser light, an optical modulator configured to modulate a frequency of the laser light by using a vibrator and add a modulation component to the laser light, and a second light receiver configured to receive the laser light containing the modulation component and a length measurement component generated when the retroreflector is irradiated with the laser light and output a second light reception signal, the length measuring optical system causing the laser light to interfere; and a driver configured to change a position of the retroreflector.

In one aspect, an apparatus includes a first light source that applies first light having a first wavelength as a center wavelength to an object, a second light source that applies second light having a second wavelength as a center wavelength longer than the first wavelength to the object, an optical filter that includes first and second regions and that transmits third light produced by the first and second light each passed through or reflected by the object, first and second optical detectors that determine first and second amounts, respectively, of the third light passed through the first and second regions. The transmission ranges of spectral transmission curves of the first and second regions are located between the first wavelength and the second wavelength. The spectral transmission curve of the first region has a width at half maximum different from that of the spectral transmission curve of the second region.

Apparatus and methods for spectral analysis of a sample are described, for example for carrying out Raman or other optical or spectroscopic analysis of samples such as pharmaceutical dosage forms, including oral solid dosage forms such as tablets or capsules. Such apparatus may comprise delivery optics arranged to direct probe light to a delivery region of the sample, collection optics arranged to collect probe light scattered from a collection region of the sample, and a spectrometer having an entrance port, the spectrometer being arranged to receive the collected probe light from the collection optics at the entrance port of the spectrometer, and to detect spectral features in the received probe light. In particular, the collection optics may comprise Koehler integration optics arranged to process the collected probe light such that the collected light from each point of the collection region is distributed across the entrance port of the spectrometer.

A new spectral measurement technique is provided which enables measurement even if the light to be measured exists for a very short period. In one embodiment, a broadband pulsed light wave whose wavelength shifts temporally and continuously in a pulse interferes with a light wave to be measured. The intensity at each wavelength of the light wave to be measured is obtained using a Fourier transform of the output signal from a detector that has detected the intensity of the wave resulting from the interference. A laser beam from a laser source is converted to a supercontinuum wave by a nonlinear optical element, and a pulse extension element extends pulses of the supercontinuum wave, thus generating the broadband pulsed light wave.

A method for adaptive dual frequency-comb spectroscopy includes repeatedly (i) recording a single interferogram with a dual frequency-comb spectrometer, (ii) averaging the single interferogram into an averaged interferogram, and (iii) determining a signal-to-noise ratio (SNR) of the averaged interferogram, until the SNR of the averaged interferogram exceeds a SNR threshold. In certain embodiments, determining the SNR includes determining a signal amplitude of a center burst of the averaged interferogram and determining a noise level of the averaged interferogram from data points of the averaged interferogram located away from the center burst. In certain embodiments, determining the SNR includes Fourier transforming the averaged interferogram into a frequency spectrum and numerically integrating the frequency spectrum.