354 results about "Reflectometry" patented technology

The present invention provides apparatuses and methods for sample analysis, such as tissue analysis, that integrate high wavenumber (HW) Raman spectroscopy for chemical composition analysis and optical coherence tomography (OCT) to provide depth and morphological information. The invention also provides side-viewing optical probes that are based on a single double clad optical fiber for performing the combined HW Raman spectroscopy and OCT. Intravascular catheter embodiments and related vascular diagnostic methods are also provided.

Common path frequency domain optical coherence reflectometry / tomography devices include a portion of optical fiber with predetermined optical properties adapted for producing two eigen modes of the optical radiation propagating therethrough with a predetermined optical path length difference. The two replicas of the optical radiation outgoing from the portion of the optical fiber are then delivered to an associated sample by an optical fiber probe. The tip of the optical fiber serves as a reference reflector and also serves as a combining element that produces a combination optical radiation by combining an optical radiation returning from the associated sample with a reference optical radiation reflected from the reference reflector. The topology of the devices allows for registering a cross-polarized or a parallel-polarized component of the optical radiation reflected or backscattered from the associated sample. Having the optical path length difference for the two eigen modes of the optical radiation (which is an equivalent of an interferometer offset in previously known devices) differ from the reference offset in the devices of the present invention allows for relieving the requirements to the spectral resolution of the FD OCT engine and / or data acquisition and processing system, and substantially eliminates depth ambiguity problems.

A spectroscopy system is provided which operates in the vacuum ultra-violet spectrum. More particularly, a system utilizing reflectometry techniques in the vacuum ultraviolet spectrum is provided for use in metrology applications. The system may further include the use of an array detector in combination with an imaging spectrometer. In this manner data for multiple wavelengths may be simultaneously collected. Moreover, the multiple wavelengths of data may be collected simultaneously for a two dimensional sample area. The system may further include the use of a fixed diffraction grating and does not require the use of polarizing elements. To ensure accurate and repeatable measurement, the environment of the optical path is controlled. The optical path may include a controlled environmental chamber in which non-absorbing purge gases are present or in which vacuum evacuation techniques are utilized. The controlled environment may further include a separate instrument chamber and a separate sample chamber. The controlled environment limits in a repeatable manner the absorption of VUV photons.

A portion of a polarization maintaining (PM) optical fiber having two polarization states is analyzed. First and second spectral responses of the PM fiber portion are determined. In a preferred implementation, the spectral responses are determined using Optical Frequency Domain Reflectometry (OFDR). Each polarization state of the PM fiber portion has a corresponding spectral component in the first spectral response. First and second spectral analyses of the PM fiber portion are performed using the first and second spectral responses. Based on those spectral analyses of the PM fiber portion, a first physical characteristic affecting the PM fiber portion is determined that is distinct from a second different physical characteristic affecting the fiber portion. Example physical characteristics include temperature and strain. An output signal related to the first physical characteristics affecting the fiber portion is provided, e.g., for display, further processing, etc.

Common path frequency domain optical coherence reflectometry / tomography devices with an additional interferometer are suggested. The additional interferometer offset is adjusted such, that it is ether less than the reference offset, or exceeds the distance from the reference reflector to the distal boundary of the longitudinal range of interest. This adjustment allows for relieving the requirements to the spectral resolution of the frequency domain optical coherence reflectometry / tomography engine and / or speed of the data acquisition and processing system, and eliminates depth ambiguity problems. The new topology allows for including a phase or frequency modulator in an arm of the additional interferometer improving the signal-to-noise ratio of the devices. The modulator is also capable of substantially eliminating mirror ambiguity, DC artifacts, and autocorrelation artifacts. The interference signal is produced either in the interferometer or inside of the optical fiber probe leading to the sample.

Polarization sensitive common path OCT / OCR devices are presented. Optical radiation from a source is converted into two cross-polarized replicas propagating therethrough with a predetermined optical path length difference. The two cross-polarized replicas are then delivered to an associated sample by a delivering device, which is, preferably, an optical fiber probe. A combination optical radiation is produced in at least one secondary interferometer by combining a corresponding portion of an optical radiation returning from the associated sample with a reference optical radiation reflected from a tip of an optical fiber of the optical fiber probe. Subject to a preset optical path length difference of the arms of the at least one secondary interferometer, a cross-polarized component, and / or a parallel-polarized component of the combined optical radiation, are selected. The topology of the devices allows for time domain, as well as for frequency domain registration.

In common path time domain OCT / OCR devices optical radiation from a source is first split into two replicas, which are then delivered to an associated sample by an optical fiber probe. The tip of the optical fiber probe serves as a reference reflector and also serves as a combining element that produces a combination optical radiation by combining an optical radiation returning from the associated sample with a reference optical radiation reflected from the reference reflector. The topology of the devices eliminates the necessity of using Faraday mirrors, and also allows for registering a cross-polarized component of the optical radiation reflected or backscattered from the associated sample, as well as a parallel-polarized component.

A CW lightwave modulated by a continuously reiterated binary pseudorandom code sequence is launched into an end of a span of ordinary optical fiber cable. Portions of the launched lightwave back propagate to the launch end from a continuum of locations along the span because of innate fiber properties including Rayleigh scattering. This is picked off the launch end and heterodyned to produce a r.f. beat signal. The r.f. beat signal is processed by a plurality (which can be thousands) of correlator type binary pseudonoise code sequence demodulators respectively operated in different delay time relationships to the timing base of the reiterated modulation sequences. The outputs of the demodulators provide r.f. time-domain reflectometry outputs representative of signals (e.g., acoustic pressure waves) incident to virtual sensors along the fiber at positions corresponding to the various time delay relationships.