A sensing system for monitoring a composition of a downhole fluid in a well, where the sensing system includes: a light source, an optical waveguide, an evanescent field sensing element that is indirect contact with a downhole fluid, and a detector. The light source is operable for emitting a beam and includes a frequency comb generator configured to modify at least a portion of the beam into a sensing comb beam. The evanescent field sensing element provides attenuated internal reflection of the sensing comb beam at the interface between the evanescent field sensing element and the downhole fluid, and the portion of the sensing comb beam interacts with the fluid to form at least a portion of an interacted beam. The detector obtains a spectral distribution of the interacted beam.

The disclosure herein provides a device, a method and a computer-readable storage medium for quantitative phase imaging, and relates to the field of quantitative phase imaging. The specific implementation scheme is: Obtain a multiplexed interferogram of the sample, where the multiplexed interferogram is a sample beam composed of at least two beams with different wavelengths to illuminate the sample and penetrate into the cube beam splitter Combine at least two beams with different wavelengths as the reference beam, and the combined beam is the imaging image sampled by the camera; and perform phase retrieval on the multiplexed interference image to obtain each beam of the sample in the composite sample beam The phase map at the wavelength of Using the embodiments of the disclosure herein, one imaging acquisition and one phase retrieval are to acquire the phase maps of at least two wavelength channels.

An optical fiber splitter device comprising at least two optical fibers of different lengths is disclosed for partial or complete compensation of the optical path difference between waves interfering to generate a hologram or an interferogram. Various implementations of this fiber splitter device are described in apparatuses for holographic and interferometric imaging of microscopic and larger samples.

Apparatus for measuring spectra from one or more samples, the apparatus including a reference waveguide that receives illuminating radiation used to illuminate at least one sample, at least one sample waveguide that receives sample radiation at least one of reflected from and transmitted through a respective sample, an optical system that spatially distributes radiation from each of the waveguides based on a frequency of the radiation, and focuses radiation from the optical fibres into an imaging plane and an imaging device that captures an image of the focused and spatially distributed radiation from the imaging plane so that the image includes respective spectra from each of the waveguides.

The invention relates to an optical system for measuring the absorption of light in a medium, comprising at least one light source for sending light and at least one optical detector, which receives the light and converts it into an electrical signal. The system is characterized in that the system comprises at least one light guide, wherein, in the region of the light source, light is coupled as reference light into the light guide, wherein the light guide is guided, at least in sections, past the medium, and wherein the light guide guides the reference light onto the detector.

Apparatus for measuring spectra from one or more samples, the apparatus including a reference waveguide that receives illuminating radiation used to illuminate at least one sample, at least one sample waveguide that receives sample radiation at least one of reflected from and transmitted through a respective sample, an optical system that spatially distributes radiation from each of the waveguides based on a frequency of the radiation, and focuses radiation from the optical fibres into an imaging plane and an imaging device that captures an image of the focused and spatially distributed radiation from the imaging plane so that the image includes respective spectra from each of the waveguides.

An optical fiber splitter device comprising at least two optical fibers of different lengths is disclosed for partial or complete compensation of the optical path difference between waves interfering to generate a hologram or an interferogram. Various implementations of this fiber splitter device are described in apparatuses for holographic and interferometric imaging of microscopic and larger samples.

The invention relates to an optical system for measuring the absorption of light in a medium, comprising at least one light source for sending light and at least one optical detector, which receives the light and converts it into an electrical signal. The system is characterized in that the system comprises at least one light guide, wherein, in the region of the light source, light is coupled as reference light into the light guide, wherein the light guide is guided, at least in sections, past the medium, and wherein the light guide guides the reference light onto the detector.

A device for measuring wafers includes an optical coherence tomograph, which generates a measuring light beam and directs it onto the wafer via an optical system. A scanning device deflects the measuring light beam in two spatial directions. A control unit controls the scanning device so that the measuring light beam scans the surface of the wafer successively at several measuring points. Two measuring points have a distance d.sub.max of 140 mmd.sub.max600 mm. An evaluation unit calculates distance values and/or thickness values from the interference signals provided by the optical coherence tomograph and, based on the distance values and/or thickness values, at least one characteristic quantity of the wafer such as TTV, warp or bow.

The disclosure herein provides a device, a method and a computer-readable storage medium for quantitative phase imaging, and relates to the field of quantitative phase imaging. The specific implementation scheme is: Obtain a multiplexed interferogram of the sample, where the multiplexed interferogram is a sample beam composed of at least two beams with different wavelengths to illuminate the sample and penetrate into the cube beam splitter Combine at least two beams with different wavelengths as the reference beam, and the combined beam is the imaging image sampled by the camera; and perform phase retrieval on the multiplexed interference image to obtain each beam of the sample in the composite sample beam The phase map at the wavelength of. Using the embodiments of the disclosure herein, one imaging acquisition and one phase retrieval are to acquire the phase maps of at least two wavelength channels.