Abstract: A laser employing a tapered, thin film interference filter as a tuning element. Tapered, thin film interference filters employing dielectric layers are disclosed for use in tuning lasers. Methods of tuning a laser by adjustably positioning a tapered thin film interference filter are disclosed. Also included are a method for tuning a laser to account or thermal wavelength drift, a method of mounting an etalon in a substantially stress free manner, and a mount therefor.

Abstract: A composite detector device that incorporates a plurality of types of detector elements to cover a broad wavelength range. There may be one or more individual detector elements of each detector type. The individual detector elements are positioned upon a single substrate so that when light from a sample passes through a spectral dispersing element, each detector element is exposed to light of a predetermined, limited wavelength range.

Abstract: A gas analysis apparatus for analysis of sample gas wherein the apparatus has a mechanism for cleaning optical elements such as reflectors and windows in the apparatus is provided. The gas analysis apparatus includes a light source for emitting light, a body having an isolated cavity in which the light emitted by the light source propagates, a detector for analyzing light scattered by the sample gas in the isolated cavity, and a spraying system connected to the body to spray a sublimable substance. The isolated cavity has one or more optical elements each with a surface. The spray of the sublimable substance is directed onto such a surface for in situ removal of contaminants. The body has a sample inlet port for introducing the sample gas into the cavity and an outlet port for venting gas from the cavity.

Abstract: A spectrograph having a collimating lens unit, a reflective diffraction grating, a focusing lens unit, and a light detector is provided. The collimating lens unit has at least one optical element with at least one aspheric surface for collimating light from a light source. This lens unit has a positive optical power and a focal ratio of at most 1.7. The reflective diffraction grating diffracts the collimated light from the collimating lens unit. The focusing lens unit also has at least one lens with at least one aspheric surface. It focuses the first order diffracted light on the light detector and has a focal length that provides an overall magnification of 0.8 to 2.0 when combined with the collimating lens unit and the diffraction grating.

Abstract: A System for Collecting Weakly Scattered Electromagnetic Radiation is disclosed. The present invention overcomes problems suffered by previous collection systems by providing a reliable and efficient device for intensifying and collecting the scattered radiation generated by laser induced scattering. The present invention employs a laser source which illuminates an unknown gas contained by a long hollow tube having a highly reflective sheathing. The illuminating electromagnetic radiation from the laser is directed along the entire length of the tube and collides with the molecules of the unknown gas in the tube. The collisions cause the emission of weakly scattered electromagnetic radiation that is shifted in reference to the illuminating radiation. The sheathing is sufficiently reflective of the scattered radiation to substantially contain it. An exit is coupled to the long hollow tube in such a way that the scattered radiation may pass from the reflective sheathing and be collected for analysis.

Abstract: Method and apparatus for determining the composition and concentration of gases present in a patient's airway by measurement of the spectrum of Raman scattered light from these gases. The efficiency is improved by collecting Raman scattered light generated outside the collection region. The gases present are assumed to be drawn from a predetermined set of gases with known Raman scattering spectra, and the concentrations are determined by solution of a matrix equation Ac=b, where the c vector components are the unknown concentrations and the b vector components are determined from measurements of the Raman scattering intensifies in a plurality of wavelength or wavenumber intervals. The linear system of equations represented by the matrix equation may be overdetermined and may require solution by non-conventional methods, such as singular value decomposition.

Abstract: A method and apparatus are disclosed for converting the 35 mm image from a conventional fundus camera into a size suitable for recording by a conventional solid state CCD module. The CCD camera connects to the fundus camera using a bayonet attachment. The aerial image created by the fundus camera is received and transmitted through the CCD camera along a folded mirror optical path, and is reduced and aligned for detection by the CCD module. The optical path contains a pair of adjustable mirrors to allow compensation for variations in the focal lengths between various fundus cameras. An articulating mirror may be included to enable the user to pan across the aerial image while recording segmented views for reconstruction by an external computer into a composite, high resolution image.

Abstract: An optical relay having a pair of simple lenses and an opaque barrier defining an aperture. In a spectrometer, the optical relay is positioned between a light source and an opaque barrier defining a slit to focus light of a reference wavelength w.sub.r onto the slit. The location of the aperture and the choice of w.sub.r are selected so that the flux of light through the slit is substantially flat as a function of wavelength.

Abstract: A photodiode assembly including a photodiode array having a linear arrangement of photodiodes, and a mask associated with the photodiode array to shade one or more selected photodiodes from incoming light of a particular frequency. The mask includes a frame provided with an elongated slot, and at least one bridge formed across the slot for shading the selected photodiode. The bridge portion is sufficiently wide to fully cover the selected photodiode and to partially cover the two adjacent photodiodes. An aperture is provided through the bridge in alignment with the selected photodiode to allow a portion of the incident light to impinge upon the selected photodiode.