Abstract:
A cooled echelle grating spectrometer for detecting wavelengths between one micron and fifteen microns. More specifically, a spectrometer is disclosed having a cross-dispersing grating for ordering infrared energy, and an echelle grating for further ordering of the infrared energy. Means are disclosed to direct infrared energy to the cross-dispersing grating and then to the echelle grating. Ordered radiation from the echelle grating is sensed by a detecting means. Means are also disclosed for cooling the cross-dispersing grating, the echelle grating and the detecting means so that background radiation can be minimized. In a specific embodiment the cross-dispersing grating and echelle grating are in separate enclosed volumes having access to each other through a single intermediate aperture, reflected energy from the cross-dispersing grating being focused so as to pass through the intermediate aperture and then collimated and directed to the echelle grating for further ordering. Also disclosed is use of a Schmidt camera for focusing the further ordered radiation from the echelle grating onto a detector array having individual detectors dispersed on a plane which substantially corresponds to a curved focal plane of the Schmidt camera. A spectrometer constructed according to the teachings of the present invention will continuously cover the spectrum between one micron and fifteen microns and have a resolution of 0.1 cm..sup.-1.
Abstract:
A method and apparatus by which spectral orders produced by a main grating are separated and focused on a focal surface of restricted size, using a combination of grating and prism for the separation of spectral orders, which provides for a relatively uniform spacing of the spectral orders over the entire wave length range within the restricted focal surface.
Abstract:
An echelle spectrometer includes a slit opening for incoming light, a collimator which collimates a diverging beam of light generated through the slit, a reflective echelle grating which disperses the collimated light along a first dimension; a cross-disperser which disperses at least a portion of the collimated light in a second dimension orthogonal to the first dimension to create a two-dimensional spectral field-of-view; and an imaging system which images the two- dimensional spectral field-of-view onto a detector; wherein the imaging system comprises primary, secondary, and tertiary tilted mirrors, where each of the tilted mirrors comprises a freeform, rotationally non-symmetric surface shape.
Abstract:
A method of spectrophotometric analysis is disclosed. There is provided a measuring system including a low-resolution spectrophotometric sensor, a device of mobile communication (such as smartphone or tablet) and software which may be installed partially on that device and partially on a remote computing server or service. The method includes calibration of a measurement channel, oriented on measuring optical spectra or spectrum- related quantities; estimation of the optical spectrum of an arbitrary, analyzed sample, on the basis of the data from the sensor and the results of calibration; and evaluation of a spectrum-related quantity on the basis of the results of estimation. These steps may include involvement of local and/or remote computing resources.
Abstract:
A spectral feature of a pulsed light beam produced by an optical source is estimated by modifying the wavelength of the pulsed Sight beam based on a predefined repeating pattern having a pattern period including, a plurality of steps, the modification including shifting the wavelength of the pulsed light beam by a wavelength offset from, a baseline wavelength for each step in the pattern period measuring the wavelength of the light beam for each step in the pattern period as the wavelength is modified across the pattern; and estimating a spectral feature of the pulsed light beam over an evaluation window that includes all of the steps within the pattern period based at least in part on the measured wavelength of the light beam for each step in the pattern period.
Abstract:
Eine Spektrometeranordnung (10) enthaltend ein Echelle-Gitter (18; 46) zur Dispersion der in die Spektrometeranordnung (10) eintretenden Strahlung in einer Hauptdispersionsrichtung, und eine Dispersionsanordnung (16; 40) zur Dispersion eines aus der in die Spektrometeranordnung eintretenden Strahlung erzeugten parallelen Strahlenbündels in einer Querdispersionsrichtung, ist dadurch gekennzeichnet, dass die Dispersionsanordnung (16; 40) reflektierend und in Bezug auf das Echelle-Gitter (18; 46) derart angeordnet ist, dass das parallele Strahlenbündel in Richtung auf das Echelle-Gitter reflektiert wird. Das Echelle-Gitter (18; 46) kann vorzugsweise derart angeordnet sein, dass die dispergierte Strahlung zurück in Richtung auf die Dispersionsanordnung (16; 40) reflektiert wird. )
Abstract:
Es wird eine Messvorrichtung zum Auslesen von in einer Lichtleitfaser angeordneten Messaufnehmern beschrieben. Die Messvorrichtung weist eine Gitteranordnung auf, die ein von den Messaufnehmern erzeugtes Eingangssignal auf verschiedene Ausgänge verteilt. Die den Ausgängen zugeordneten Transmissionscharakteristika (12) weisen dabei einen möglichst großen Überlappungsbereich auf, um den Messbereich der Messvorrichtung zu erhöhen.
Abstract:
Ein hochauflösendes Spektrometer (10) ist mit einem Eintrittsspalt (12), einem dispergierenden Element (16), einer Kameraoptik (14), und einer Detektoranordnung mit einem Detektor (22) ausgestattet. Die optischen Komponenten sind analog zu einer Littrow-Anordnung so zueinander angeordnet, dass Strahlung, welche durch den Eintrittsspalt (12) in das Spektrometer (10) eintritt, mittels der Kameraoptik (14) auf das dispergierende Element (16), und danach bis auf einen kleinen Winkel (y) in sich zurück über die gleiche Kameraoptik (14) leitbar und auf dem Detektor (22) fokussierbar ist. Es sind ferner Mittel (18, 20) zur Erzeugung einer Mehrfachdispersion durch das dispergierende Element (16) vorgesehen. Das Spektrometer ist dadurch gekennzeichnet, dass die Mittel zur Erzeugung der Mehrfachdispersion wenigstens zwei reflektierende, ebene Flächen (18, 20) umfassen, die miteinander einen rechten Winkel bilden und welche die dispergierte und fokussierte Strahlung (3) zuerst in Richtung auf eine der jeweils anderen reflektierenden Flächen und dann in Richtung auf das dispergierende Element (16) zurückreflektieren. Die reflektierenden Flächen sind so angeordnet sind, dass sich der Eintrittsspalt (12) in der Schnittlinie der Ebenen befindet, welche durch die reflektierenden Flächen (18, 20) definiert sind.
Abstract:
A method and apparatus for in-process transient spectroscopic analysis of a molten metal, wherein a probe (10) containing a pulsed high-power laser (14) producing a pulsed laser beam having a substantially triangular pulse waveshape is immersed in the molten metal and irradiates a representative quantity of the molten metal. The pulsed laser beam vaporizes a portion of the molten metal to produce a plasma plume having an elemental composition representative of the elemental composition of the molten metal. Before the plasma plume reaches thermal equilibrium shortly after termination of the laser pulse, a spectroscopic detector (241) in the probe (10) detects spectral line reversals, during a short first time window. Thereafter, when the afterglow plasma is in thermal equilibrium, a second spectroscopic detector (242) also in the probe (10) performs a second short time duration spectroscopic measurement. A rangefinder (22) measures and controls the distance between the molten metal surface and the pulsed laser (14).
Abstract:
A method of optical spectroscopy for analysing a sample using an optical spectrometer is provided. The method comprises obtaining a sample spectrum of the sample using the optical spectrometer and obtaining a blank spectrum using the optical spectrometer. The blank spectrum comprises structured background radiation which is correlated with the sample spectrum. A cross-correlation of the sample spectrum and the blank spectrum is determined. A mapped blank spectrum is generated by mapping the blank spectrum to the sample spectrum based on the cross-correlation, and the mapped blank spectrum is subtracted from the sample spectrum to generate a background corrected sample spectrum.