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 spectrograph having multiple excitation wavelength ranges is disclosed. The spectrograph can include a wavelength switching mechanism to switch between different wavelength ranges in accordance with the wavelength of an incoming light signal. The wavelength switching mechanism can include multiple optical assemblies (or elements) corresponding to the different wavelength ranges for processing the incoming light signal. The mechanism can also include a switching component for switching the optical assemblies to align the appropriate assembly with the incoming light signal. Each optical assembly can include one or more transmission gratings to disperse the incoming light signal into multiple wavelengths within a particular wavelength range and a reflecting mirror proximate to the grating(s) to reflect the wavelengths of light back through the grating(s) to photodetectors for measuring to wavelengths to generate a light spectrum. The spectrograph can be used in Raman spectroscopy.
Abstract:
A method of forming an image of a target that comprises illuminating a target with light, maneuvering an optical unit having at least one diffractive element in front of the target through a plurality of positions, capturing, during the maneuvering, a plurality of spectrally encoded frames each from a portion of the light that is scattered from a different of a plurality of overlapping segments along a track traversing an image plane of the target, and combining the plurality of spectrally encoded frames to form a composite multispectral image of at least a portion of said target.
Abstract:
A spectrometry apparatus includes a transmissive diffraction grating that transmits incident light. The transmissive diffraction grating has inclined surfaces made of a first dielectric material. The inclined surfaces are arranged so that they are inclined relative to a reference line. When the angle of incidence of light incident on the transmissive diffraction grating is measured with respect to the reference line and defined as an angle α, and the angle of diffraction of diffracted light is measured with respect to the reference line and defined as an angle β, the angle of incidence α is smaller than a Bragg angle θ defined with respect to the inclined surfaces, and the angle of diffraction β is greater than the Bragg angle θ.
Abstract:
A wavelength detecting apparatus capable of detecting the main wavelength of the light coming into an image capture apparatus and a focus detecting apparatus using the same are disclosed. The wavelength detecting apparatus may include a spectral unit which separates the incoming light according to the respective wavelengths, and may focus the separated light onto a sensor. The main wavelength can be determined based on the wavelength distribution sensed by the sensor. The determined wavelength can be used to further determine amount of adjustment to be made to the defocus amount to compensate for the chromatic aberration associated with the wavelength of the light illuminating the source.
Abstract:
The invention relates to angle-limiting optical reflectors and optical dispersive devices such as optical spectrum analyzers using the same. The reflector has two reflective surfaces arranged in a two-dimensional corner reflector configuration for reflecting incident light back with a shift, and includes two prisms having a gap therebetween that is tilted to reflect unwanted light and transmit wanted light. A two-pass optical spectrum analyzer utilizes the reflector to block unwanted multi-pass modes that may otherwise exist and degrade the wavelength selectivity of the device.
Abstract:
A spectroscope is described comprising an incident slit, a collimator lens type optical system that makes the light rays having passed through the incident slit parallel light rays, a reflection type diffraction grating that receives the parallel light rays and, according to the wavelength, outputs these light rays at different angles, a condenser lens type optical system that condenses the output light from the diffraction grating, and a two-dimensional detector having a two-dimensional light-receiving surface that detects the light rays that have been condensed by the condenser lens type optical system.
Abstract:
A method of generating a design pattern for a spatial radiation modulator to encode two or more selected spectral components in one or more spectral ranges for the chemometric analysis of a group of analytes. The method includes obtaining a corresponding spectrum for each of the analytes, defining a set of initial spectral windows, constructing a chemometric matrix to relate concentrations of the analytes to intensities of the spectral components, deriving optimized spectral windows, and translating the center wavelength and the bandwidth of each of the optimized spectral windows into a corresponding optimized annular region on the modulator.
Abstract:
Performing high-resolution determination of the relative shift of the spectral properties of a biosensor. The shift in the resonance peak of the biosensor is indicative of the amount of material bound to the surface of the biosensor. A preferred biosensor is a Guided Mode Resonant Filter Biosensor (GMRFB). In one aspect of the invention, curve fitting is used to determine the relative location of the spectrum of the unexposed biosensor with respect to those spectra that are altered (e.g., shifted) by the presence of materials bound to the surface of the biosensor. In an alternative embodiment, the cross correlation function is used to detect spectral peak offsets between a reference spectrum and a spectrum measured from an exposed biosensor. In yet another alternative, maximal likelihood estimation techniques are used to determine the spectral shift or offs.
Abstract:
In a wavelength calibration method, an observed spectrum of a light that has a wavelength band is obtained, wherein the light has at least an attenuated wavelength component that corresponds to at least a predetermined absorption wavelength that is included in the wavelength band. A corrected spectrum is then obtained from the observed spectrum, wherein the corrected spectrum has reduced dependencies upon the full width at half maximum of an emission band of the light and upon an intensity ripple period of the light.