195 results about "Differential absorption" patented technology

The invention discloses a gas differential absorption laser radar based on a non-coherent light source. The laser radar uses a non-coherent light source, laser of two operating wavelengths is filtered by a filtering technology, one operating wavelength is positioned on the peak value of a gas absorption line, the other operating wavelength deviates from the gas adsorption line, and the differential adsorption detection of an atmosphere gas ingredient can be realized through the detection of the atmosphere echo signal of two beams of laser. A time division multiplexing technology is adopted, only one detector is used for finishing the measurement of reference laser and signal light, and a system integration level is improved. According to the gas differential absorption laser radar, the gas (such as water vapour, CO2, HCN, CO and the like), which is positioned in a non-coherent light source frequency spectrum range, of the gas adsorption line can be realized. A non-coherent detection technology, a wavelength division multiplexing technology and the time division multiplexing technology are adopted to realize the detection of gas ingredients, and the gas differential absorption laser radar has the advantages of high system integration degree, all fiber linking, compact structure, low construction cost, relatively safe human eyes and the like.

A continuous wave Light Detection and Ranging (CW LiDAR) system utilizes two or more laser frequencies and time or range shifted pseudorandom noise (PN) codes to discriminate between the laser frequencies. The performance of these codes can be improved by subtracting out the bias before processing. The CW LiDAR system may be mounted to an artificial satellite orbiting the earth, and the relative strength of the return signal for each frequency can be utilized to determine the concentration of selected gases or other substances in the atmosphere.

The invention discloses an inversion method of micro-pulse differential absorption lidar water vapor spatial and temporal distribution. The inversion method comprises wavelength selection of water vapor detection, calculation and correction of absorption cross sections of water vapor absorption wavelengths and non-absorption wavelengths, and inversion and calibration of water vapor concentrations. An automatic continuous detection device of the micro-pulse differential absorption lidar water vapor spatial and temporal distribution is employed to obtain characteristic backward scattering signals of water vapor absorption in specific spectral lines, the backward scattering signals are subjected to inversion and calibration by a computer utilizing a differential absorption spectrum analysis method, and high-time-resolution, high-spatial-resolution and high-precision water vapor stereo distribution data is obtained.

The invention provides a differential absorption spectrum air quality inspecting system, which comprises a photo source, a photo source launching device, a photo source receiving device, a spectroscope, photovoltaic conversion equipment and a data processing system. The photo source launching device and the photo source receiving device are separately positioned on the two sides of the photo source, a light path which goes through the gas to be inspected is formed of the light sent out by the photo source through the photo source launching device and the photo source receiving device, and the light signal produced is imported into the spectroscope through optical fiber, and the light signal is then transformed into electrical signal through the photo electricity commutating equipment; Finally, the data processing system adopts the signal analysis method of the Fourier transformation to process the spectrum, and the absorbance curve line of the gas inspected is obtained; and the density of the gas inspected can be obtained according to the intensity of the absorbance curve line and the Lambert-beer law.

The invention discloses a laser radar is based upon lame light source difference absorption process to test thickness of NO2 in the atmosphere, it includes lame light source, light incept and spectrum components, photo-detection and control transaction components, the characteristic is that the light incept and spectrum components accepts the scattered light from atmosphere backward by telescope tube of incept light, after coupling of light fiber, making the light to lay in the focal plane of lens, ripping into the raster by collimation lens, after section out the wave length of light 354.71nm and 360.00nm,recepted by the two emergent light fiber on the focal plane of lens. The raster is blazed grating, it has definite included angle with lens; the photo-detection and control transaction part includes microcomputer, data acquisition card, chronotron, enlarge shaping circuit, photomultiplier and photo-electricity probe. The invention has the beneficial purpose of easy structure, low cost, high diffraction efficiency, good flexibility, convenient using and vindicate etc.

An optical system of satellite-borne differential absorption spectrometer comprises a relay optical system and an Offner imaging spectrometer system. The relay optical system is composed of a relay reflector, relay lenses and a color separation filter. The Offner imaging spectrometer system is composed of an incident slit, a convex grating, and a concave reflector. The relay optical system uses the color separation filter to split a detection waveband to form four channels, which are focused by four groups of relay lenses to the incident slit of the spectrometer. Light at each waveband entersthe spectrometer from the incident slit of the spectrometer, is split by the convex grating, and has the light path turned and focused on a detector. The invention utilizes a relay reflector to turn the light path, and utilizes the color separation filter to split the detection waveband into four channels, to therefore improve the detection resolution of the system, ensure measurement accuracy and realize compact volume of the whole optical system. The Offner imaging spectrometer has excellent imaging spectrum performance and reduced distortion. The invention facilitates miniaturization and weight reduction of the whole system, and is suitable for space technology.

A system and method that images biological samples and uses chromophores to analyze the imaged samples. The chromophore analysis can be done by itself or in conjunction with fluorophore analysis in High Content Imaging systems. To perform chromophore analysis the biological samples can be labeled with different chromophores and imaged using transmitted light that is at least partially absorbed by the chromophores. To also perform fluorophore analysis the samples can also be labeled with fluorophores that are excited by excitation light. The chromophore analysis and fluorophore analysis can be performed separately or concurrently using a High Content Imaging system. The system provides the expanded capability by illuminating the chromophore-labeled samples with transmitted light of different wavelengths and automatically detecting the images which represent the differential absorption of the colored lights by the sample.

A method for measuring, from a thermal device, temperature, molecular number density, and/or pressure of a gaseous compound as function of distance, the gaseous compound absorbing at least some light. The method comprises generating, for a first wavelength band and a second wavelength band, a pulse sequence comprising a light pulse or light pulses, guiding the pulse sequence into the thermal device, and measuring, as function of time, the intensity of the scattered light at the first wavelength band and at the second wavelength band. The method further comprises determining information indicative of the differential absorption between the two wavelengths bands using measured intensities and determining the temperature, the molecular number density, and/or the pressure of the gaseous compound using the information indicative of the differential absorption between the two wavelengths bands. A thermal system arranged to carry out the method.

The invention provides a pulse infrared differential absorption laser radar system for detecting a carbon dioxide concentration profile, which comprises a laser emitting subsystem, an optical receiving subsystem and a data acquisition processing subsystem, wherein the laser emitting system comprises a seed laser, an Nd: YAG laser, a dye laser, a first reflecting mirror, a first half-reflecting half lens, a second half-reflecting half lens, a frequency doubling crystal, a difference frequency crystal, a first spectroscope and a wavelength control unit. The system can not only detect column concentration of atmospheric CO2, but also can obtain CO2 concentration profile distribution on a vertical path, particularly atmospheric CO2 concentration information near a boundary layer, and has important significance for carbon cycle research. The system has the advantages of low technical requirements, high stability, high detection precision and easy popularization, and is an important means for achieving atmospheric CO2 concentration profile measurement.

A multiple energy x-ray source capable of rapidly generating and delivering x-rays in the form of successive pulses that alternate between at least two different energy levels, as well as a multiple energy x-ray inspection apparatus for inspecting moving objects that employs such a multiple energy x-ray source, are provided. The inventive x-ray source facilitates the use of differential absorption characteristics as a means for distinguishing materials contained within objects during a moving inspection.

The invention provides a coherent differential absorption laser radar comprising a first tunable continuous wave laser, a second tunable continuous wave laser, a beam splitter, an acousto-optic modulator, a laser amplifier, a circulator, a transmitting and receiving telescope, a coupler, a balance detector, an acquisition card and a digital signal processing system. Two required laser wavelengthsare determined by selecting appropriate absorption lines of gas molecules to be tested in intermediate infrared, then local oscillation light and signal light are split by the beam splitter, frequencies are finally combined by the coupler, and the balance detector is used for detection to obtain a concentration of the gas molecules. Due to the larger gas absorption cross-section coefficient and lower background radiation of the intermediate infrared, the detection sensitivity is improved. The use of coherent detection instead of direct detection reduces the influence of low quantum efficiencyon the precision of detection, improves the utilization of echo signals, and improves the performance of the differential absorption laser radar.

Functional imaging for localization in biological tissue entails measuring a response in the tissue (240) to electromagnetic radiation. A catheter (200) for real-time monitoring of cardiac ablation is employed to distinguish a hemorrhage zone (232) from the sandwiching necrotic and healthy tissue, or to distinguish exogenous photoacoustic contrast agent from bordering native tissue. A pair of wavelengths is selected for differential absorption (244) of the radiation in, correspondingly, the hemorrhage zone or where the contrast agent exists, and relatively similar absorption elsewhere. Near infrared laser or LED light may be used photoacoustically to serially acquire (S310, S320) the two datasets to be compared, each representative of a time waveform. Alternatively, acquisition is for a pair of wavelength bands of microwave-induced thermoacoustic data. In either case, the members of the dataset pair are combined (110, 122) by subtraction or division to effect the piece-wise cancellation/enhancement for display (218) of the resulting signal in real time.

The invention discloses a method and a device for measuring sulfur content in coal by ultraviolet absorption spectroscopy. In the measurement method, the decomposition scale and a threshold are determined adaptively by combining empirical mode decomposition with 3sigma criterion, and non-stationary characteristics of differential absorption degree per se can be fully retained, so the spectral interference problem caused by dust, water vapor and background gas in combustion gas is effectively solved; the instantaneous concentration of SO2 is obtained through calculation according to the differential absorption degree after noise reduction and trend term removal, and the total sulfur content accumulated in the coal sample combustion gas is calculated through the gas flow; the sulfur content in the coal can be obtained by dividing the coal sample amount by the total sulfur content separated from the coal sample combustion; and the pretreatment process needed to be performed on the combustion gas by coulometric titration and an infrared absorption method is avoided. The device for measuring the sulfur content in the coal by the ultraviolet absorption spectroscopy comprises a combustion furnace, a measuring chamber, an ultraviolet light source, a spectrometer, an air purifying device, a flow meter, a waste gas treatment device, a computer, and the like.

The invention relates to a method for measuring backscattering coefficient of atmospheric particulates and ozone concentration profile simultaneously. A dual-wavelength differential absorption laser radar receives On and Off dual-wavelength backscattering echo signals of different cross sections of ozone simultaneously, and the acquired On and Off dual-wavelength backscattering echo signals are subjected to pretreatments such as background deduction, square distance correction, filtering and the like; the initial ozone concentration value is assumed, the atmospheric molecule mode is a united states standard atmosphere mode, the corrected off wavelength echo signal is utilized to invert the Off wavelength backscattering coefficient, and the On wavelength backscattering coefficient is obtained according to the wavelength conversion relation, and the ozone concentration is inverted in combination with the On wavelength backscattering echo signal; if the difference between the inverted ozone concentration and the initial ozone concentration value is more than a preset value, the above process is carried out in a loop iteration manner until the difference reaches the preset value, and therefore, the backscattering coefficient of atmospheric particulates and ozone concentration can be obtained simultaneously. The method can effectively reduce aerosol interference and improve the zone measurement precision.

A triacetone triperoxide cloud associated with a triacetone triperoxide explosive attached to a hard target is remotely detected by operating differential-absorption lidar lasers to transmit a laser beam toward the hard target at differing wavelengths. A backscattered laser beam reflected from the lidar target (hard target, person, aerosols, clouds, buildings) is detected because a cloud of triacetone triperoxide in front of the lidar target and between the lidar target and the differential-absorption lidar system produces a differential-absorption signal having characteristics that identify the triacetone triperoxide. In a second embodiment, a triacetone triperoxide cloud that is absorbing optical radiation from its ambient environment and which is attached to a hard target is detected from a location remote from the triacetone triperoxide explosive by detecting an optical radiation absorption signature characterized by triacetone triperoxide absorption lines.

Low concentrations of water vapor within a background of one or more hydrocarbon gases may be detected and quantified using a differential absorption spectrometer. A dehydrated sample of the gas is used as a background sample whose absorption spectrum allows elimination of absorption features not due to water vapor in the gas. Absorption spectra may recorded using tunable diode lasers as the light source, these lasers may have a wavelength bandwidth that is narrower than the water vapor absorption feature used for the differential absorption spectral analysis.

The invention relates to a front-mounted optical system of a satellite-borne differential absorption spectrometer. The front-mounted optical system consists of a front-mounted telescope and a relay reflector. The front-mounted telescope further consists of a primary mirror and a secondary mirror, and the primary mirror and the secondary mirror of the telescope as well as the relay reflector are all designed in an off-axis manner and respectively have the off-axis angles of 4 DEG, -6 DEG and 5 DEG; radiant light of a target object passes through an entrance pupil diaphragm and irradiates to the primary mirror, and light beams are reflected to the secondary mirror of the front-mounted telescope by a polarization scrambler through an aperture diaphragm, then are reflected to the relay reflector through a slit, and finally are focused to an incident slit of a spectrometer by the relay reflector; and then a wide view field telescope system of the two mirrors is realized through controllingpositions of diaphragms and the off-axis angles. The front-mounted optical system of the satellite-borne differential absorption spectrometer has the advantages of fewer mirrors, high utilization efficiency of radiant energy, wide range of working spectrum and no chromatic correction, thus the measuring accuracy and the surveying distinguishability of the whole system are enhanced; and in addition, the whole optical volume is compact, thereby greater convenience is brought for a successive optical system.

The invention discloses a multi-axial differential absorption spectrometer calibration system and a method. The system comprises a telescope, wherein back scattering light received by the rear end of the telescope is input into a spectrograph through an optical fiber. The system is characterized in that: the middle part of a telescope tube is provided with a front hole and a rear hole; a telescopic standard lamp component and a standard gas calibration tank component are arranged in the front hole and the rear hole respectively; the standard lamp component comprises a first substrate; a mercury lamp and a tungsten halogen lamp are arranged in the two through holes on the first substrate respectively; the standard gas calibration tank component comprises a second substrate; and a sulfur dioxide standard gas absorption tank and a nitrogen dioxide standard gas absorption tank are arranged in the two through holes on the second substrate respectively. By adopting the system, the two problems existing in the conventional multi-axial differential absorption spectrum system are solved; spectrum calibration, detector bad pixel detection and standard gas calibration are provided for the system; and the measurement accuracy for an instrument is improved.

A dual-wavelength Raman mode locked laser, belonging to the solid laser technology field, comprises a laser diode pumping source, a coupling lens unti, a resonant cavity, etc. A laser crystal, a Raman crystal and a Q-switching device are placed in the resonant cavity. A temperature control system enables the above crystals and the device to keep constant in temperature. The dual-wavelength Raman mode locked laser is characterized in that Nd is utilized: after a BaWO4 crystal conducts a 925cm<1> Raman frequency shift on 1059nm and 1061nm dual-wavelength fundamental frequency light generated by a CNGG crystal, 1173nm and 1175nm dual-wavelength Raman light is produced; the end faces of an input lens M1, the laser crystal and the Raman crystal are all plated with dielectric films that have the reflectivity or transmittance not less than 99% to the light with the corresponding wavelengths, and an output lens M2 is plated with a dielectric film that has the reflectivity not less than 99% to the light with the corresponding wavelengths of 1059nm and 1061nm and also plated with a dielectric film that has the reflectivity ranging from 10% to 15% to the light with the wavelengths of 1173nm and 1175nm; and mode locking is performed through the stimulated Raman scattering effect of the Raman crystal, and the pulse width reach the ps magnitude. The dual-wavelength Raman mode locked laser is small in size and simple in structure, provides light beams of great quality, and has important application prospects in terms of terahertz wave generation, differential absorption of laser radar and the like.