Abstract:
An optical coherence tomography (OCT) apparatus includes an optical source, an interferometer generating an object beam and a reference beam, a transverse scanner for scanning an object with said object beam, and a processor for generating an OCT image from an OCT signal returned by said interferometer. At least the optical source, the interferometer, and the scanner are mounted on a common translation stage displaceable towards and away from said object. A dynamic focus solution is provided when the scanner and a folded object path are placed on the translation stage.
Abstract:
A spectral interferometry apparatus and method are disclosed, that can be used to monitor or measure an unknown length by following a characteristic of an indicating signal. The measurement is performed by adjusting an optical path difference (OPD) in an interferometer until sound or light or both are obtained with the desired strength and pitch. Embodiments are presented where the unknown length is the eye length. Sound of different pitches are produced by scanning the channeled spectrum output of an interferometer with the object returning at least one of the interferometer optical signals. The scanning is performed by reading the signal of an analogue photodetector array driven by a nonlinear clock or by tuning a low cost swept source using a distorted driving signal.
Abstract:
The invention discloses an optical interferometer which can be used to provide simultaneous measurements over multiple path lengths and methods to employ such an interferometer as to achieve a variety of functions covering simultaneous measurements at different depths separated by an increment of a multiple differential delay matched in the interferometer as well as imaging. Optical sensors, optical coherence tomography (OCT) set-ups, optical sensing methods and OCT methods are disclosed which can provide: (i) multiple en-face images at several depths with dynamic dispersion compensation, (ii) fast acquisition of cross sections, (iii) fast acquisition of 3D volumes of a scattering object while maintaining dynamic focus; (iv) fast acquisition of long axial measurement profiles, non mechanical, with dynamic focus, range scalable, with applications in tracking and OTDR. Methods are disclosed on the combination of scanning regimes and modes of operation to achieve versatile functionality in measurements, in the 3D imaging of moving tissue such as the eye, heart, or moving embryos or functional/low noise imaging by making use of angular compounding or polarisation. A method for elimination of axial movement effects in measuring the flow profile is also disclosed.
Abstract:
Optical mapping apparatus for imaging an object, comprising an optical coherence tomography (OCT) system including an OCT source, an OCT reference path leading from the OCT source to an OCT receiver, an OCT object path leading from the object to the OCT coupler, an OCT depth scanner adapted to alter at least one of the OCT reference path and the OCT receiver path. A confocal system is provided including a confocal optical receiver a confocal path leading from the object to the confocal optical receiver via a confocal input aperture. An adaptive optics (AO) system is provided to correct optical aberrations in the OCT object path and the confocal path.
Abstract:
OCT apparatus includes an interferometer, having an input beam splitter and a 50/50 output splitter. The splitting ratio of the input splitter may be optimized depending on the source power of light source and on the mismatch of the balanced receiver. The input splitter is a plate beam-splitter to minimize the stray reflected light in the interferometer and allow sequential operation of the apparatus in the OCT or in the confocal regime. The switching between the two regimes may be at will, or synchronous with the en-face scanning which results in quasi-simultaneous OCT/confocal imaging or in alternatives frames, confocal and OCT. By using polarization sensitive elements, two channels are provided in each regime, OCT and confocal. The two confocal polarization sensitive channels may allow adjustments of compensators prior to OCT measurements or OCT imaging.
Abstract:
Methods and devices are disclosed for acquiring depth resolved aberration information using principles of low coherence interferometry and perform coherence gated wavefront sensing (CG-WFS). The wavefront aberrations is collected using spectral domain low coherence interferometry (SD-LCI) or time domain low coherence interferometry (TD-LCI) principles. When using SD-LCI, chromatic aberrations can also be evaluated. Methods and devices are disclosed in using a wavefront corrector to compensate for the aberration information provided by CG-WFS, in a combined imaging system, that can use one or more channels from the class of (i) optical coherence tomography (OCT), (ii) scanning laser ophthalmoscopy, (iii) microscopy, such as confocal or phase microscopy, (iv) multiphoton microscopy, such as harmonic generation and multiphoton absorption. For some implementations, simultaneous and dynamic aberration measurements/correction with the imaging process is achieved. The methods and devices disclosed can provide wavefront sensing in the presence of stray reflections from optical interfaces.
Abstract:
A spectral interferometry apparatus and method is provided to supply unambiguous profiles (A—scans free of mirror terms) of the reflectivity versus optical path difference and make difference between the positive and negative optical path difference or provide output in a selected interval of optical path differences. The apparatus comprises object optics that transfer a beam from an optical source to a target object (55) to produce an object beam and reference optics that produce a reference beam. Displacing means (57) are provided to produce a gap (g) between the object beam (41′) and the reference beam (42′). Optical spectrum dispersing means (7) such as a grating or a prism receive the two relatively displaced beams, and disperse their spectral content onto a reading element such as a CCD. The combination of the displacing means and the optical spectrum dispersing means creates an intrinsic optical delay between the wavetrains of the object beam and the reference beam which can be used with the optical path difference in the interferometer to generate a channeled spectrum for the optical path difference in the interferometer on the reading element.
Abstract:
OCT apparatus includes an interferometer, having an input beam splitter and a 50/50 output splitter. The splitting ratio of the input splitter may be optimized depending on the source power of light source and on the mismatch of the balanced receiver. The input splitter is a plate beam-splitter to minimize the stray reflected light in the interferometer and allow sequential operation of the apparatus in the OCT or in the confocal regime. The switching between the two regimes may be at will, or synchronous with the en-face scanning which results in quasi-simultaneous OCT/confocal imaging or in alternatives frames, confocal and OCT. By using polarization sensitive elements, two channels are provided in each regime, OCT and confocal. The two confocal polarization sensitive channels may allow adjustments of compensators prior to OCT measurements or OCT imaging.
Abstract:
A spectral interferometry apparatus and method is provided to supply unambiguous profiles (A-scans free of mirror terms) of the reflectivity versus optical path difference and make difference between the positive and negative optical path difference or provide output in a selected interval of optical path differences. The apparatus comprises object optics that transfer a beam from an optical source to a target object (55) to produce an object beam and reference optics that produce a reference beam. Displacing means (57) are provided to produce a gap (g) between the object beam (41′) and the reference beam (42′). Optical spectrum dispersing means (7) such as a grating or a prism receive the two relatively displaced beams, and disperse their spectral content onto a reading element such as a CCD. The combination of the displacing means and the optical spectrum dispersing means creates an intrinsic optical delay between the wavetrains of the object beam and the reference beam which can be used with the optical path difference in the interferometer to generate a channelled spectrum for the optical path difference in the interferometer on the reading element
Abstract:
The invention discloses an optical interferometer which can be used to provide simultaneous measurements over multiple path lengths and methods to employ such an interferometer as to achieve a variety of functions covering simultaneous measurements at different depths separated by an increment of a multiple differential delay matched in the interferometer as well as imaging. Optical sensors, optical coherence tomography (OCT) set-ups, optical sensing methods and OCT methods are disclosed which can provide: (i) multiple en-face images at several depths with dynamic dispersion compensation, (ii) fast acquisition of cross sections, (iii) fast acquisition of 3D volumes of a scattering object while maintaining dynamic focus; (iv) fast acquisition of long axial measurement profiles, non mechanical, with dynamic focus, range scalable, with applications in tracking and OTDR. Methods are disclosed on the combination of scanning regimes and modes of operation to achieve versatile functionality in measurements, in the 3D imaging of moving tissue such as the eye, heart, or moving embryos or functional/low noise imaging by making use of angular compounding or polarisation. A method for elimination of axial movement effects in measuring the flow profile is also disclosed.