Ludwig-Maximilians-Universitat München

Massachusetts Institute of Technology

Lightlab Imaging, Inc.

Ludwig-Maximilians-Universitaet Muenchen

Optores Gmbh

Robert Alexander Huber

Wolfgang Wieser

Thomas Klein

Christoph Eigenwillig

Benjamin Biedermann

James G Fujimoto

Sebastian Karpf

Matthias Eibl

Desmond Christopher Adler

Tom Pfeiffer

Dieter Muellner

Michael Eder

Tony H Ko

Maciej Wojtkowski

Vivek Srinivasan

Wolfgang Draxinger

A method comprises: splitting laser light into sample light, reference light, and monitor light; routing the reference light into a reference arm of an OCT interferometer; routing the monitor light into a monitor device, which generates at least one optical monitor signal representing at least one time-dependent property of the monitor light; generating at least one electric monitor signal from the at least one optical monitor signal; illuminating in a point-shaped manner a sample with sample light, wherein the illumination point is guided on the surface of the sample along a predetermined trajectory; superimposing the light scattered by the sample with the reference light emerging from the reference arm to generate an electric OCT signal; wherein the at least one electric monitor signal and the electric OCT signal are AD-converted in alternating sequence, in each case equidistantly in time, to form a single digital data stream.

Method for monitoring time-dependent properties of light during scanning swept-source optical coherence tomography

The invention relates to a method for maintaining the synchronism of a Fourier Domain Mode Locked (FDML) laser, the FDML laser comprising at least one dispersion-compensated resonator with at least one variably wavelength-selective optical filter, the laser light circulating in the resonator at a circulation frequency, and the wavelength selectivity of the filter being repeatedly modified at a syntonising rate, the FDML laser being synchronous when the syntonising rate is an integral multiple of the circulation frequency. Said method is characterised by the following steps: a) at least a portion of the laser light is coupled out of the resonator; b) at least a portion of the decoupled laser light is detected by means of a photodetector; c) amplitudes in the measuring signal of the photodetector are counted during successive counting intervals; and d) the circulation frequency or syntonising rate is adjusted such that the ratios of the count value to the lengths of the counting intervals are maintained within a predetermined nominal value interval.

Method for preserving the synchronism of a Fourier Domain Mode Locked (FDML) laser

Described is a system for inducing and detecting multi-photon processes, in particular multi-photon fluorescence or higher harmonic generation in a sample. The system comprises a dynamically-controllable light source, said dynamically-controllable light source comprising a first sub-light source, said first sub-light source being electrically controllable such as to generate controllable time-dependent intensity patterns of light having a first wavelength, and at least one optical amplifier, thereby allowing for active time-control of creation of multi-photon-excitation. The system further comprises a beam delivery unit for delivering light generated by said dynamically-controllable light source to a sample site, and a detector unit or detector assembly for detecting signals indicative of said multi-photon process, in particular multi-photon fluorescence signals or higher harmonics signals.

System and method for inducing and detecting multi-photon processes in a sample

A swept source OCT system and related method are disclosed. The system comprises a control device for operating a tunable light source in response to an electronic sweep control signal such that the tunable light source carries out wave length sweeps with a repetition rate f, which depends on the frequency of the sweep control signal. The system further comprises a detection device for the time-resolved detection of an interference signal from a sample beam and a reference beam with the help of a detection cycle signal. The sweep control signal and the detection cycle signal are phase-locked, or means for creating a signal or signal sequence are provided, said signal or signal sequence being characterising for the frequency relationship and/or the relative phase position of the sweep control signal and detection cycle signal.

Swept source OCT system and method with phase-locked detection

At least one embodiment of the method is designed to create a two-dimensional image of a three-dimensional sample. The method comprises the following steps: provision of a wave-length-tunable light source () that emits primary radiation (P) with wavelengths that vary over time; sampling of location points of the sample () with the primary radiation (P); collection of secondary radiation (S), wherein the secondary radiation (S) is a part of the primary radiation (P) reflected by the sample (); creation of an interferometer-based detection signal for a plurality of sample areas, each with at least one location point, using a detection unit (), wherein the detection signal is created as a difference signal from two output signals of a beam splitter () that receives reference radiation (R) and/or secondary radiation (S) at two inputs, wherein the reference radiation (R) is a portion of the primary radiation (P) that is not guided to the sample (); and determination of a brightness value for at least one of the sample areas from the associated detection signal, wherein the determination of the brightness values is not substantially based on the summation of the individual signal amplitudes of the results of a Fourier transformation.

Method for reducing the dimensionality of a spatially registered signal derived from the optical properties of a sample, and device therefor

Disclosed herein is a system () for measuring light induced transmission or reflection changes, in particular due to stimulated Raman emission. The system comprises a first light source () for generating a first light signal having a first wavelength, a second light source () for generating a second light signal having a second wavelength, an optical assembly () for superposing said first and second light signals at a sample location (), and a detection means () for detecting a transmitted or reflected light signal, in particular a stimulated Raman signal caused by a Raman-active medium when located at said sample location. Here in at least one of the first and second light sources () is one or both of actively controllable to emit a time controlled light pattern or operated substantially in CW mode and provided with an extra cavity modulation means () for generating a time controlled light pattern. The detection means () is capable of recording said transmitted or reflected light signal, in particular stimulated Raman signal, as a function of time.

System and method for stimulated raman spectroscopy

Disclosed herein is a coherent dynamically controllable narrow band light source (), comprising a first sub-light source (), said first sub-light source being electrically controllable such as to generate controllable time-dependent intensity patterns of light having a first wavelength, a Raman active medium () suitable to cause Raman scattering of light having said first wavelength, a second sub-light source () capable of emitting light with a second wavelength, said second wavelength being longer than said first wavelength, and an optical fiber or wave guide, wherein said light emitted by said first and second sub-light sources traverses a length of said optical fiber () or wave guide in a feed-forward configuration to facilitate a non-linear wavelength conversion step involving said Raman-active medium. At least one of said first and second sub-light sources () has a coherence length longer than 0.05 mm, preferably longer than 0.5 mm and most preferably longer than 2 mm.

Coherent dynamically controllable narrow band light source

A Fabry-P&#xe9;rot tuneable filter device is described with reflecting elements separated by an optical path length to form an optical resonator cavity. A first actuator means is directly or indirectly coupled with a first reflecting element. And the first actuator means is configured to modulate the optical path length between first and second reflecting elements by a modulation amplitude to thereby sweep the optical resonator cavity through a band of optical resonance frequencies with a sweep frequency of 70 kHz or more. And the mechanical coupling between selected elements of the arrangement is sufficiently low such that when operated at the sweep frequency, the selected elements act as a system of coupled oscillating elements. In addition or alternatively, the first actuator means is directly or indirectly coupled with the first reflecting element so as to substantially drive the first reflecting element only.

Dynamical Fabry-Perot tuneable filter device

In at least one embodiment, a wavelength-tunable light source includes at least one fiber-based partial section and at least one delay section. For a wavelength &#x3bb; of at least one portion of a radiation emitted by the light source as a function of time t, the relationship &#x3bb;(t)=&#x3bb;(t&#x2212;&#x3c4;) holds true. In this case, &#x3c4; is a specific period of time. Furthermore, the delay section includes one or more oligomode fibers.

Wavelength-tunable light source

A control system for improving and stabilizing Fourier domain mode locking (FDML) operation. The control system may also provide regulation of FDML operational parameters such as filter tuning, laser gain, polarization, polarization chromaticity, elliptical polarization retardance, and/or dispersion. The control system may be located internal to or external from the FDML laser cavity.

Fourier domain mode locking: method and apparatus for control and improved performance

A Fabry-P&#xe9;rot tunable filter device is described with reflecting elements separated by an optical path length to form an optical resonator cavity. A first actuator means is directly or indirectly coupled with a first reflecting element. And the first actuator means is configured to modulate the optical path length between first and second reflecting elements by a modulation amplitude to thereby sweep the optical resonator cavity through a band of optical resonance frequencies with a sweep frequency of 70 kHz or more. And the mechanical coupling between selected elements of the arrangement is sufficiently low such that when operated at the sweep frequency, the selected elements act as a system of coupled oscillating elements. In addition or alternatively, the first actuator means is directly or indirectly coupled with the first reflecting element so as to substantially drive the first reflecting element only.

Dynamical Fabry-P&#xe9;rot tuneable filter device

In at least one embodiment of the wavelength-tunable light source (), it comprises an output source (), which is capable in operation of generating electromagnetic radiation (R). Furthermore, the light source () has a wavelength-selective first filter element (), which is situated downstream from the output source (). Moreover, the light source () contains a first amplifier medium (), which is situated downstream from the first filter element () and is capable of at least partial amplification of the radiation (R) emitted by the output source (). The light source () further comprises at least one wavelength-selective second filter element (), which is situated downstream from the first amplifier medium (), the second filter element () having an optical spacing (L) to the first filter element (). The first filter element () and the at least one second filter element () are tunable via a control unit (), which the light source () has. The filter elements () are tuned for this purpose so that first filter element () and second filter element () are transparent to a partial radiation (P) of the radiation (R) in a time delay (T) to one another, the delay (T) being equal to the quotient of the optical spacing (L) and the speed of light in vacuum (c).

In one aspect, the invention relates to a method of acquiring optical coherence tomographic data from a sample. The method includes the steps of scanning a first location on the sample to obtain a first set of optical coherence tomographic data, scanning a second location on the sample to obtain a second set of optical coherence tomographic data, and defining a fiducial position relative to a location on the sample using one of the two sets of optical coherence tomographic data. In one embodiment, the first set of optical coherence tomographic data is survey data. However, in another embodiment the first set of optical coherence tomographic data is sample measurement data.

Methods and apparatus for optical coherence tomography scanning

In at least one embodiment of the wavelength-tunable light source, it comprises an output source, which is capable in operation of generating electromagnetic radiation. Furthermore, the light source has a wavelength-selective first filter element, which is situated downstream from the output source. Moreover, the light source contains a first amplifier medium, which is situated downstream from the first filter element and is capable of at least partial amplification of the radiation emitted by the output source. The light source further comprises at least one wavelength-selective second filter element, which is situated downstream from the first amplifier medium, the second filter element having an optical spacing to the first filter element. The first filter element and the at least one second filter element are tunable via a control unit, which the light source has.

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Schnaitsee, Germany

Robert Alexander Huber