In a method for calibrating a gas sensorfor determining a gaseous species concentration in a gas, which species absorbs light in an absorption spectral bandthe gas sensor includes a chamber for containing the gas; a light source through which a supply electrical current is passable to raise the light source to a temperature; a measurement photodetector for measuringin a measurement spectral band comprising the absorption spectral banda measured intensity of a light beam emitted by the light source and transmitted by the gas in the chamber; and a reference photodetector for measuring a reference intensity of a reference light beam emitted by the light source in a reference spectral band. A non-linear calibration function is determined to estimate an intensity, measured in the measurement spectral band by the measurement photodetector in the absence of gaseous species, from a reference intensity measured in the reference spectral band.

The disclosure relates to a non-dispersive infrared (NDIR) gas sensor which detects the concentration of gas with a simple structure and method by manufacturing an optical waveguide with a gas-permeable polymer material instead of a conventional cavity or chamber type. An optical signal travels through the optical waveguide of gas-permeable polymer by total internal reflection, and the gas naturally penetrates the optical waveguide without the use of separate inlet and outlet openings, so that the optical signal and gas particles come into contact with each other within the optical waveguide. Since the optical signal detected by a photodetector at the other end of the optical waveguide after traveling while contacting the gas particles has properties changed according to the concentration of the gas which they have contacted in the optical waveguide, it is possible to measure the concentration of a specific gas from the detected optical signal.

Disclosed is a sensor and method for detecting one or more gasses in a sample. The sensor includes two sample tube sections, which allow for a larger sample, and correspondingly, more accurate measurement. Having two sample tube sections increases the total length of the sample path. However, placing the sample tube sections in parallel allows for the performance of the sensor to be enhanced, but the footprint of the sensor to remain unchanged. Light pipe material may be used to transport the light between sample tube sections. Further, light pipe material may be used to move the IR lamp away from the first filter tube section, reducing problems in the thermopile by dissipating heat from the IR lamp away from the sample tube section.

Methods, assemblies, and controllers may be used for determining and using standardized spectral responses for calibration of spectroscopic analyzers. The methods, assemblies, and controllers may be used to calibrate or recalibrate a spectroscopic analyzer when the spectroscopic analyzer changes from a first state to a second state, the second state being defined as a period of time after a change to the spectroscopic analyzer causing a need to calibrate or recalibrate the spectroscopic analyzer. The calibration or recalibration may result in the spectroscopic analyzer outputting a standardized spectrum, such that the spectroscopic analyzer outputs a corrected material spectrum for an analyzed material, and defining the standardized spectrum. The corrected material spectrum may include signals indicative of material properties of an analyzed material, the material properties of the material being substantially consistent with material properties of the material output by the spectroscopic analyzer in the first state.

The invention is directed to a multi-wavelength process photometer (20) for quasi-continuously determining the absorption of a liquid sample, comprising a continuous-spectrum flashlight source (24), a transparent liquid sample measurement cell (40) which is radiated by the flashlight source (24), a translucent light diffusor element (50) behind the measurement cell (40) for homogenously diffusing the light of the flashlight source (24) coming from the liquid sample measurement cell (40), and at least two different wavelength-selective light detectors (61, 62, 63) behind the light diffusor element (50), wherein the light detectors (61, 62, 63) have substantially the same distance (X4) to the light diffusor element (50).

An optical device for detecting a first chemical species and a second chemical species contained in a specimen, which includes: a first optical sensor, which may be optically coupled to an optical source through the specimen and is sensitive to radiation having a wavelength comprised in a first range of wavelengths; and a second optical sensor, which may be optically coupled to the optical source through the specimen and is sensitive to radiation having a wavelength comprised in a second range of wavelengths, different from the first range of wavelengths.

The invention relates to a method for determining concentrations of absorbing gases by means of a spectroscopic measuring device, wherein wavelength-dependent measurement values for a light intensity are obtained and a wavelength-dependent measurement value function is represented based on these values. A wavelength-dependent theoretical function is defined, which includes as parameters a calibration parameter and the concentrations. The calibration parameter is defined as a function of a device parameter and a correction parameter that depends on the concentrations. A cycle comprising a sequence of steps is performed several times in a row, wherein in a first step a numerical value for the correction factor is calculated from stipulated assumed values of the concentrations, wherein in a second step the theoretical function is determined using the calculated numerical value, wherein in a third step values for the concentrations are obtained by a curve adjustment calculation between the theoretical function determined in the second step and the measurement value functions and are stipulated as new assumed values. The assumed values obtained in the third step of the last cycle are output as new measured values.

This disclosure provides a method for imaging lymph nodes and lymphatic vessels without a contrast agent. The method includes providing, using an optical source, an infrared illumination to a region of a subject having at least one lymphatic component, detecting a reflected portion of the infrared illumination directly reflected from the region using a sensor positioned thereabout, and generating at least one image indicative of the at least one lymphatic component in the subject using the reflected portion of the infrared illumination.

This disclosure provides a method for imaging lymph nodes and lymphatic vessels without a contrast agent. The method includes providing, using an optical source, an infrared illumination to a region of a subject having at least one lymphatic component, detecting a reflected portion of the infrared illumination directly reflected from the region using a sensor positioned thereabout, and generating at least one image indicative of the at least one lymphatic component in the subject using the reflected portion of the infrared illumination.

Methods and assemblies may be used for determining and using standardized spectral responses for calibration of spectroscopic analyzers. The methods and assemblies may be used to calibrate or recalibrate a spectroscopic analyzer when the spectroscopic analyzer changes from a first state to a second state, the second state being defined as a period of time after a change to the spectroscopic analyzer causing a need to calibrate or recalibrate the spectroscopic analyzer. The calibration or recalibration may result in the spectroscopic analyzer outputting a standardized spectrum, such that the spectroscopic analyzer outputs a corrected material spectrum for an analyzed material, and defining the standardized spectrum. The corrected material spectrum may include signals indicative of material properties of an analyzed material, the material properties of the material being substantially consistent with material properties of the material output by the spectroscopic analyzer in the first state.