In one embodiment of the invention, a semiconductor optical amplifier (SOA) in a laser ring is chosen to provide low polarization-dependent gain (PDG) and a booster semiconductor optical amplifier, outside of the ring, is chosen to provide high polarization-dependent gain. The use of a semiconductor optical amplifier with low polarization-dependent gain nearly eliminates variations in the polarization state of the light at the output of the laser, but does not eliminate the intra-sweep variations in the polarization state at the output of the laser, which can degrade the performance of the SS-OCT system.

A method of assessing tissue health comprises the steps of obtaining depth-resolved spectra of a selected area of in vivo tissue, and assessing the health of the selected area based on the depth-resolved structural information of the scatterers. Obtaining depth-resolved spectra of the selected area comprises directing a sample beam towards the selected area at an angle, and receiving an angle-resolved scattered sample beam. The angle-resolved scattered sample beam is cross-correlated with the reference beam to produce an angle-resolved cross-correlated signal about the selected area, which is spectrally dispersed to yield an angle-resolved, spectrally-resolved cross-correlation profile having depth-resolved information about the selected area. The angle-resolved, spectrally-resolved cross-correlation profile is processed to obtain depth-resolved information about scatterers in the selected area.

An optical measurement apparatus includes a light source unit generating and outputting light, a polarized light generating unit generating polarized light from the light, an optical system generating a pupil image of a measurement target, using the polarized light, a self-interference generating unit generating multiple beams that are split from the pupil image, and a detecting unit detecting a self-interference image generated by interference of the multiple beams with each other.

A 3-D imaging system including a computer determining a plurality of coherence factors measuring an intensity contrast between a first intensity of a first region of an interference comprising constructive interference between a sample wavefront and a reference wavefront, and a second intensity of a second region of the interference comprising destructive interference between the sample wavefront and the reference wavefront, wherein the interference between a reference wavefront and a reflection from different locations on a surface of an object. From the coherence factors, the computer determines height data comprising heights of the surface with respect to an x-y plane perpendicular to the heights and as a function of the locations in the x-y plane. The height data is useful for generating a three dimensional topological image of the surface.

Retinal imaging systems and related methods employ a user specific approach for controlling the reference arm length in an optical coherence tomography (OCT) imaging device. A method includes restraining a user's head relative to an OCT imaging device. A reference arm length adjustment module is controlled to vary a reference arm length to search a user specific range of reference arm lengths to identify a reference arm length for which the OCT image detector produces an OCT signal corresponding to the retina of the user. The user specific range of reference arm lengths covers a smaller range of reference arm lengths than a reference arm length adjustment range of the reference arm length adjustment module.

A system may include a broadband light source emitting polarized light that is polarized to two orthogonal polarization states, multiple beam splitters for combining and splitting the polarization states, and interferometric cell for creation of interference patterns with respect to a sample surface, lenses of appropriate design that focus the polarized light at predefined locations, and sensors that analyze the polarized light as a function of angle and wavelength. The system may also include a controller configured to modulate the reference arm through operation of an optical chopper and allow for different data analysis modes to be used on the system produced data.

Apparatus include a polarization state generator situated to provide an interferometer source beam with a region of polarized source light with a polarization state that is in-plane as subsequently incident on a sample and a region of polarized source light with a polarization state that is perpendicular to in-plane as subsequently incident on the sample, and an interferometer unit configured to split the interferometer source beam into test and reference arm beams, to direct the test arm beam to the sample and the reference arm beam to a reference surface, and to recombine the test and reference arm beams to produce an interferometer output beam. Methods use a polarization state generator to produce an interferometer source beam with a region of polarized source light with a polarization state that is in-plane as subsequently incident on a sample and a region of polarized source light with a polarization state that is perpendicular to in-plane as subsequently incident on the sample, and use an interferometer unit which splits the interferometer source beam into test and reference arm beams, directs the test arm beam to the sample and the reference arm beam to a reference surface, and recombines the test and reference arm beams to produce an interferometer output beam.

Apparatus and methods are presented for spectral domain optical imaging, in particular for single shot 3-D spectral domain imaging of the retina of the human eye. In certain embodiments one or more 3-D images across elongated areas of an object are acquired, with scanning perpendicular to the long axis of the elongated areas for imaging extended volumes of the object. In preferred embodiments the captured light is sampled in the Fourier plane, in a dimension substantially perpendicular to the long axis, with a cylindrical lenslet array, while in other embodiments the captured light is sampled in the image plane. Apparatus and methods are also presented for hyperspectral imaging of the retina, with the illuminating beams preferably angled to suppress interference from corneal reflections. Apparatus and methods are also presented for multi-wavelength wavefront sensing, with simultaneous capture of light in two or more paths with different delays.

There is provided a system and method of a method of detecting a local shape deviation of a structural element in a semiconductor specimen, comprising: obtaining an image comprising an image representation of the structural element; extracting, from the image, an actual contour of the image representation; estimating a reference contour of the image representation indicative of a standard shape of the structural element, wherein the reference contour is estimated based on a Fourier descriptor representative of the reference contour, the Fourier descriptor being estimated using an optimization method based on a loss function specifically selected to be insensitive to local shape deviation of the actual contour; and performing one or more measurements representative of one or more differences between the actual contour and the reference contour, the measurements indicative of whether a local shape deviation is present in the structural element.

Retinal imaging systems and related methods employ a user specific approach for controlling the reference arm length in an optical coherence tomography (OCT) imaging device. A method includes restraining a user's head relative to an OCT imaging device. A reference arm length adjustment module is controlled to vary a reference arm length to search a user specific range of reference arm lengths to identify a reference arm length for which the OCT image detector produces an OCT signal corresponding to the retina of the user. The user specific range of reference arm lengths covers a smaller range of reference arm lengths than a reference arm length adjustment range of the reference arm length adjustment module.