Abstract:
An infrared spectrometer includes an infrared source system that is stabilized to provide a substantially constant output light intensity. The infrared source system includes a source element adapted to receive electrical power and to emit light at an intensity related to the electrical power received by the source element. A light detector is mounted in position to receive light emitted from the source element and to provide an output signal related to the intensity of the light received by the detector. A feedback control loop receives the signal from the detector and provides electrical power to the source element to maintain the intensity of the light output from the source element at a selected level as detected by the detector.
Abstract:
Methods and apparatus for contemporaneous measurements of electromagnetic radiation with multiple measuring devices, for producing a high diagnostic sensitivity image while achieving high diagnostic specificity with spectroscopy, for producing illumination for fluorescence/NIR reflectance imaging and white light reflectance imaging, all with the same sensors are disclosed. The method may involve selectively adjusting a gain of an imaging device in at least one wavelength band relative to a gain in at least one other band to produce an optimized image of an object, and may also involve producing a first reflectance signal in a first NIR wavelength band, and producing a second reflectance signal in a second NIR band such that an absorption coefficient ratio of oxyhemoglobin to deoxyhemoglobin in the second wavelength band differs from that in the first wavelength band, to permit the first and second reflectance signals to be used to produce a tissue oxygenation image.
Abstract:
A Littrow-type spectrometer or monochromator using a folded light path to provide a compact optical instrument is disclosed. Light enters the instrument through an inlet aperture on a planar mirror. The aperture is located at the focus of a parabolic collimator mirror. Collimated light reflected by the parabolic mirror is reflected back to the planar mirror, which is positioned at an angle to the collimated light. The light reflected from the planar mirror is directed at a planar grating that produces diffracted light having all the wavelengths input into the system, including light of a selected wavelength, back towards the planar mirror. Light having the selected wavelength is thus caused to fall on the parabolic mirror. The parabolic mirror then focuses the selected wavelength of light onto a light exit aperture that is juxtaposed to the inlet light aperture. The planar grating can be rotatably mounted to scan the input light spectrum.
Abstract:
An optical system having a first order spectral range that is usable in an optical spectrum analyzer receives an broadband optical test signal and a optical calibration signal and couples the optical signals via two optically isolated paths to separate optical detectors. First and second pairs of optical fibers, with each pair having an input fiber and an output fiber, are positioned in a focal plane of a collimating optic that has an optical axis. The fiber pairs are symmetrically positioned on either side of the optical axis with the input fibers positioned on one side of the optical axis and the output fibers positioned on the opposite side of the optical axis. The input fibers receive the optical test signal and the optical calibration signal. The output optical fibers are coupled to first and second optical detectors. An optical calibration source generates second order or greater spectral lines that fall within the first order spectral range of the optical system. A diffraction grating receives the optical test signal and the optical calibration signal from the collimating optic and separates the first order spectral components of the broadband optical test signal and passes the second order or greater spectral lines of the optical calibration signal. The first optical detector that is responsive to the first order spectral components of the optical test signal receives the optical test signal from the collimating optic and converts the optical test signal to an electrical signal. A second optical detector that is responsive to the second order or greater spectral lines of the optical calibration signal concurrently receives the optical calibration signal from the collimating optic and converts the calibrations signal to an electrical signal.
Abstract:
A small-spot imaging, spectrometry instrument for measuring properties of a sample has a polarization-scrambling element, such as a Lyot depolarizer, incorporated between the polarization-introducing components of the system, such as the beamsplitter, and the microscope objective of the system. The Lyot depolarizer varies polarization with wavelength. Sinusoidal perturbation in the resulting measured spectrum can be removed by data processing techniques or, if the depolarizer is thick or highly birefringent, may be narrower than the wavelength resolution of the instrument.
Abstract:
A color detecting apparatus and process in which light from a source is directed to a surface whose color is to be measured through an aspheric lens situated so that reflected radiation is returned to the aspheric lens along a reversely directed path. The aspheric lens collimates the reflected light from the surface and directs it to two or more detectors which are tuned to receive energy in two or more preselected band widths along paths which are substantially of equal length with each detector receiving energy in substantially same cross-sectional area of the collimated beam.
Abstract:
A compact monochromator with entrance and exit slits nearly incident permitting insertion and removal of the monochromator at a focal point without requiring change in the system. A monochromator with entrance and exit slits each formed by an edge and a mirror. A monochromator with entrance slit and mirror directing the beam through an aperture in a grating to a collimating mirror, defining a light path from the entrance slit and mirror to the collimating mirror to the grating and back to the collimating mirror to the exit mirror and slit.
Abstract:
Apparatus for use in the measurement of the API gravity of crude oil, comprises a conduit (1) for the oil, a thermocouple (4) in the conduit for measuring temperature of the oil in contact therewith, a sapphire window (3) in the conduit, an infrared thermometer (5,6) for the measurement of the temperature of the oil through the window, and means (20) for comparing the measurements of temperature made by the thermometers to obtain a measure of the emissivity of the crude oil and thereby its API gravity.