Process for measuring emission for a flame in an open combustion environment. A captured image is received from each of a plurality of image capturing devices in at least one selected spectral band. Each of the plurality of image capturing devices is trained on the flame from the combustion process from a different perspective view angle. A spectral path length of the flame in the at least one spectral band is estimated from the captured images. Emitted radiance of the flame is estimated from the captured images, and a temperature of the flame is estimated from the estimated emitted radiance. A gas species concentration of the flame is estimated from the temperature of the flame and the spectral path length of the flame. Emission for the flame is measured from the gas species concentration.

Systems and methods disclosed herein use a multi-color pyrometer configured to determine a first temperature in a high temperature range and a single-color pyrometer configured to determine second temperature in a low temperature range. The system uses information gained from determination of the first temperature in the high temperature range to facilitate later determining the second temperature in the low temperature range. The first temperature in the high temperature range and the second temperature in the low temperature range are used to monitor and control different engine operations that occur at different times.

A temperature measuring system is disclosed herein. The temperature measuring system includes an optical assembly and a spectral data receiver. The temperature measuring system views passing gas and measures the radiant response of a selected gas. The measurement includes radiant intensities with respect to wavelengths in the infrared region.

Described herein are a spectrometer system and a spectrometer device, which are suited for investigation or monitoring purposes, in particular, in the infrared (IR) spectral region, and for a detection of heat, flames, fire, or smoke. The spectrometer device allows capturing incident light from object and transferring the incident light to a length variable filter with a particularly high concentration efficiency. Apart from the spectrometer device, the spectrometer system further includes an evaluation unit designated for determining information related to a spectrum of an object by evaluating the detector signals provided by the spectrometer device.

A temperature measuring device includes a Fabry-Perot interferometer, a power supply, and a light source. The temperature measuring device observes the light emitted from the light source and transmitted through the Fabry-Perot interferometer and obtains the temperature of a measurement environment in which the Fabry-Perot interferometer is placed. The light source emits a plurality of lights to the Fabry-Perot interferometer.

A method for estimating the oxide thickness and the temperature of a heated steel strip, undergoing a heat treatment performed at a temperature from 100° C. to 1100° C., including the steps of 1. measuring at least two radiation intensities at different wavelengths, in a range from 1 to 5 μm, emitted by the heated steel strip, 2. estimating the temperature of the heated steel strip, T.sub.ESTIMATED, based on the at least two measured radiation intensities and a reference radiation intensity for at least a reference wavelength, emitted by a reference steel strip having a determined oxide layer thickness, estimating the emissivity coefficient of the heated steel strip, ε.sub.ESTIMATED, using at least one of the measured radiation intensities and the estimated temperature, T.sub.ESTIMATED, 4. estimating the oxide thickness, Ox.sub.ESTIMATED, of the heated steel strip using the estimated emissivity, ε.sub.ESTIMATED.

Various embodiments disclosed herein describe an infrared (IR) imaging system for detecting a gas. The imaging system can include an optical filter that selectively passes light having a wavelength in a range of 1585 nm to 1595 nm while attenuating light at wavelengths above 1600 nm and below 1580 nm. The system can include an optical detector array sensitive to light having a wavelength of 1590 that is positioned rear of the optical filter.

Various embodiments disclosed herein describe an infrared (IR) imaging system for detecting a gas. The imaging system can include an optical filter that selectively passes light having a wavelength in a range of 1585 nm to 1595 nm while attenuating light at wavelengths above 1600 nm and below 1580 nm. The system can include an optical detector array sensitive to light having a wavelength of 1590 that is positioned rear of the optical filter.

An integrated photonics chip for thermal imaging comprises a photonics substrate including a plurality of receiver elements. Each receiver element comprises a first grating coupler optically coupled to a first waveguide filter and configured to receive a first wavelength of light at a given angle, with the first waveguide filter configured to pass the first wavelength of light; and a second grating coupler optically coupled to a second waveguide filter and configured to receive a second wavelength of light at the given angle, with second waveguide filter configured to pass the second wavelength of light. Each receiver element receives the wavelengths of light from an object of interest that emits the light due to blackbody radiation, and receives the wavelengths of light at respectively different angles. Each grating coupler receives a unique wavelength of light with respect to the other wavelengths of light received by the other grating couplers.

A background subtracted spectrometer for airborne infrared radiometry. The background subtracted spectrometer may comprise: a filter array, a detector, and a dewar containing liquid nitrogen. The filter array may be configured to selectively pass different spectral bands of infrared radiation. The filter array may comprise: at least one linear variable filter and a plurality of bandpass filters. The detector may comprise a focal plane array configured to receive the different spectral bands of infrared radiation simultaneously transmitted through the filter array. The detector may generate one or more electrical signals indicative of infrared radiation intensity as a function of wavelength. The filter array may be coupled to the focal plane array of the detector, and the filter array and detector may be conductively cooled by the liquid nitrogen to improve signal-to-noise ratio and spectral measurements. The background subtracted spectrometer preferably lacks a circular variable filter and relay lens.