Abstract:
Spectrometric gratings formed by holographic techniques are disclosed. The gratings are employed in monochromator mounts of the type in which fixed entrance and exit slits are combined with simple rotation of the grating to scan the spectral range of interest, the angles of incidence and diffraction and the positions of the slits being so related that the mounts are characterized by improved optical performance due to phase balancing and improved focussing properties according both to geometrical and diffraction theories. The parameters involved in the holographic formation of the gratings, specifically the angularities and positions of the point sources forming the holographic image of the grating lines, are specifically related to the characteristics of the mount as to improve further their optical characteristics, particularly with respect to mounts either employing "normal" (i.e., relatively small) angles of incidence with large grating apertures or employing grazing incidence (i.e., for use in the far ultraviolet region).
Abstract:
PROBLEM TO BE SOLVED: To provide a diffraction grating designed to prevent diffraction efficiency from being lowered by a shadow generated by a grating groove, and designed to reduce extremely an aberration caused by conical diffraction, and a conical diffraction oblique-incidence spectroscope provided with the diffraction grating. SOLUTION: In this diffraction grating spectroscope provided with a converged beam generating means (concave mirror 2) for converting a dispersed beam from a light source or an inlet slit 1 into a converged beam, and the diffraction grating (plane diffraction grating 3) arranged on an optical path ranging over from the light source to a focal point of the converged beam, and for conducting wavelength scanning by turning the diffraction grating around an axis determined in parallel to a grating groove direction of a grating face thereof, an expansion coefficient for a groove function of a series expansion showing a groove pattern of the diffraction grating is determined to make all of a rotating axis (y-axis) of the diffraction grating, an incident main beam and a diffraction main beam coplanar, and to bring a value of an expansion coefficient of an optical path function for expressing the focal point of a spectroscopic system including the diffraction grating into substantially zero in at least one wavelength within a wavelength range for conducting the wavelength scanning.
Abstract:
Methods and systems for performing simultaneous spectroscopic measurements of semiconductor structures over a broad range of angles of incidence (AOI), azimuth angles, or both, are presented herein. Spectra including two or more sub-ranges of angles of incidence, azimuth angles, or both, are simultaneously measured over different sensor areas at high throughput. Collected light is linearly dispersed across different photosensitive areas of one or more detectors according to wavelength for each subrange of AOIs, azimuth angles, or both. Each different photosensitive area is arranged on the one or more detectors to perform a separate spectroscopic measurement for each different range of AOIs, azimuth angles, or both. In this manner, a broad range of AOIs, azimuth angles, or both, are detected with high signal to noise ratio, simultaneously. This approach enables high throughput measurements of high aspect ratio structures with high throughput, precision, and accuracy.
Abstract:
A Sagnac interferometer can include a beamsplitter arranged to receive an input beam of light of a design wavelength, to split the input beam of light into first and second beams that counter propagate around an optical path, and to recombine the first and second beams into an output beam of light. The optical path can include at least one diffraction grating that is arranged to satisfy an effective Littrow geometry.
Abstract:
A Sagnac interferometer can include a beamsplitter arranged to receive an input beam of light of a design wavelength, to split the input beam of light into first and second beams that counter propagate around an optical path, and to recombine the first and second beams into an output beam of light. The optical path can include at least one diffraction grating that is arranged to satisfy an effective Littrow geometry.
Abstract:
The present invention discloses apparatuses and methods for non-invasive determination of attributes of human tissue by quantitative infrared spectroscopy. The embodiments of the present invention include subsystems optimized to contend with the complexities of the tissue measurements. The subsystems can include an illumination/modulation subsystem, a tissue sampling subsystem, a calibration maintenance subsystem, a data acquisition subsystem, and a computing subsystem. Embodiments of the present invention provide analyte property determination and identity determination or verification from the same spectroscopic information, making unauthorized use or misleading results less likely that in systems that include separate analyte and identity determinations. The invention can be used to prevent operation of automobiles or other equipment unless the operator has an acceptable alcohol concentration, and to limit operation of automobiles or other equipment to authorized individuals who are not intoxicated or drug-impaired.
Abstract:
The invention relates to a method of obtaining stigmatic imaging in spectral analysis using a concave grating in offplane mounts. The invention comprises placing on one hand the object, which may be an entrance slit, and on the other the focal surface in such a manner with respect to the concave grating that certain conditions specified in disclosed formulae and relating to an othogonal three dimensional coordinate system the origo of which lies in the middle of the grating surface, the X-axis of which runs along the normal to the grating surface, and the Z-axis of which is parallel with the grooves of the grating, are satisfied at a value for the angle between the XY-plane and a line from a selected point on the object to origo that differs from zero.
Abstract:
The grating of an asymmetric, double pass, grating monochromator has an axis of rotation which extends at an angle Psi relative to a normal to a plane H H''. That plane is normal to, and bisects, a line extending between the monochromator entrance and exit slits. The angle Psi is characterized in that spectral overlap is substantially elmininated.