Abstract:
A spectral feature of a pulsed light beam produced by an optical source is estimated by modifying the wavelength of the pulsed light 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:
A diffraction grating structure having ultra-high density of grooves comprises an echellette substrate having periodically repeating recessed features, and a multi-layer stack of materials disposed on the echellette substrate. The surface of the diffraction grating is planarized, such that layers of the multi-layer stack form a plurality of lines disposed on the planarized surface of the structure in a periodical fashion, wherein lines having a first property alternate with lines having a dissimilar property on the surface of the substrate. For example, in one embodiment, lines comprising high-Z and low-Z materials alternate on the planarized surface providing a structure that is suitable as a diffraction grating for EUV and soft X-rays. In some embodiments, line density of between about 10,000 lines/mm to about 100,000 lines/mm is provided.
Abstract:
An Echelle spectrometer arrangement (10) with internal order separation contains an Echelle grating (34) and a dispersing element (38) for order separation so that a two-dimensional spectrum having a plurality of separate orders (56) can be generated, an imagine optical system (18, 22, 28, 46), a flat-panel detector (16), and predispersion means (20) for predispersing the radiation into the direction of traverse dispersion of the dispersion element (38). The arrangement is characterized in that the predispersion means (20) comprise a predispersion element which is arranged along the optical path behind the inlet spacing (12) inside the spectrometer arrangement. The imaging optical system is designed in such a manner that the predispersed radiation can be imaged onto an additional image plane (24) which does not have any boundaries in the predispersion direction and which is arranged along the optical path between the predispersion element (20) and the echelle grating (34). Optical means (20, 68) in the area of the predispersed spectrum are arranged to influence the spatial and/or the spectral beam density distribution on the detector (16).
Abstract:
A spectrograph including a primary mirror, a secondary mirror, and a tertiary mirror forming a TMA having a common vertex axis. The spectrograph also may include a collimating mirror, a diffraction grating, and a dispersive prism. The collimating mirror and an entrance aperture form an interchangeable module. Radiation received through the entrance aperture is reflected in a collimated pattern towards an aperture stop. The diffraction grating, located between the collimating mirror and prism, diffracts radiation passed through the aperture stop into multiple beams directed onto the prism. A flat mirror, located to one side of the vertex axis. receives and reflects the multiple beams exiting the prism onto the primary mirror, where they are reflected onto the secondary mirror. The secondary mirror reflects the beams to the tertiary mirror where they are reflected onto an image plane located on the other side of the vertex axis.
Abstract:
A portable spectrograph including a primary mirror, a secondary mirror, and a tertiary mirror forming a TMA having a common vertex axis, a diffraction grating, and a dispersive prism, where the portable spectrograph can detect wavelengths between 150 nm and 1.1 μm. The portable spectrograph also may include a collimating mirror and an entrance aperture, which form an interchangeable module. Radiation received through the entrance aperture is reflected in a collimated pattern towards an aperture stop. The diffraction grating, located between the collimating mirror and prism, diffracts radiation passed through the aperture stop into multiple beams directed onto the prism. A flat mirror, located to one side of the vertex axis receives and reflects the multiple beams exiting the prism onto the primary mirror, where they are reflected onto the secondary mirror. The secondary mirror reflects the beams to the tertiary mirror where they are reflected onto an image plane located on the other side of the vertex axis.
Abstract:
An illumination subsystem configured to provide illumination for a measurement system includes first and second light sources configured to generate light for measurements in different wavelength regimes. The illumination subsystem also includes a TIR prism configured to be moved into and out of an optical path from the first and second light sources to the measurement system. If the TIR prism is positioned out of the optical path, light from only the first light source is directed along the optical path. If the TIR prism is positioned in the optical path, light from only the second light source is directed along the optical path. Various measurement systems are also provided. One measurement system includes an optical subsystem configured to perform measurements of a specimen using light in different wavelength regimes directed along a common optical path. The different wavelength regimes include vacuum ultraviolet, ultraviolet, visible, and near infrared wavelength regimes.
Abstract:
An apparatus is described for the real-time identification of one or more selected components of a target material. In one embodiment, an infrared spectrometer and a separate Raman spectrometer are coupled to exchange respective spectral information of the target material preferably normalized and presented in a single graph. In an alternative embodiment, both an infrared spectrometer and a Raman spectrometer are included in a single instrument and a common infrared light source is used by both spectrometers. In another embodiment, a vibrational spectrometer and a stoichiometric spectrometer are combined in a single instrument and are coupled to exchange respective spectral information of the target material and to compare the spectral information against a library of spectra to generate a real-time signal if a selected component is present in the target material.
Abstract:
The invention relates to a spectrometer arrangement (10) having a spectrometer for producing a spectrum of radiation from a radiation source on a detector (34), comprising an optical imaging Littrow arrangement (18, 20) for imaging the radiation entering the spectrometer arrangement (16) in an image plane, a first dispersion arrangement (28, 30) for the spectral decomposition of a first wavelength range of the radiation entering the spectrometer arrangement, a second dispersion arrangement (58, 60) for the spectral decomposition of a second wavelength range of the radiation entering the spectrometer arrangement, and a common detector (34) arranged in the image plane of the imagine optics, characterized in that the imaging optical arrangement (18, 20) comprises an element (20) that can be moved between two positions (20, 50), wherein the radiation entering the spectrometer arrangement in the first position is guided via the first dispersion arrangement and in the second position via the second dispersion arrangement.
Abstract:
A diode laser spectroscopy gas sensing apparatus having a diode laser with a select lasing frequency, a pitch optic coupled to the diode laser with the pitch optic being operatively associated with a process chamber and oriented to project laser light along a projection beam through the process chamber. This embodiment additionally includes a catch optic in optical communication with the pitch optic to receive the laser light projected through the process chamber and an optical fiber optically coupled to the catch optic. In addition, the catch optic is operatively associated with a catch side alignment mechanism which provides for the alignment of the catch optic with respect to the projection beam to increase a quantity of laser light received by the catch optic from the pitch optic and coupled to the optical fiber and a detector sensitive to the select lasing frequency optically coupled to the optical fiber. The catch side alignment mechanism may consist of means to tilt the catch optic along a first axis and a second axis orthogonal to the first axis with both the first and second axes being approximately orthogonal to the projection beam.
Abstract:
Echelle gratings and microelectromechanical system (MEMS) digital micromirror device (DMD) detectors are used to provide rapid, small, and highly sensitive spectrometers. The new spectrometers are particularly useful for laser induced breakdown and Raman spectroscopy, but could generally be used with any form of emission spectroscopy. The new spectrometers have particular applicability in the detection of improvised explosive devices.