Carl Zeiss Meditec Ag

Ralf Ebersbach

Martin Hacker

Gerard Antkowiak

Thomas Pabst

Ferid Bajramovic

Roland Bergner

Matthias Reich

Peter Klopfleisch

Tobias Bühren

Wilfried Bissmann

Eberhard Hofmann

Manfred Dick

Michael Bergt

Ingo Koschmieder

Roland Barth

Rudolf Von Buenau

Adolf Friedrich Fercher

Klaus-Ditmar Voigt

Beate Böhme

Rainer Leitgeb

Steffen Dubnack

Robert Pomraenke

Martin Volkwardt

Lothar Müller

Michael Güntzschel

Ulf Peterlein

Heino Weigand

Stephan Laqua

Thomas Hamann

Michael Guentzschel

Branislav Grajciar

Rudolf Von BÜNAU

Tobias BÜHREN

A method of controlling a semiconductor-laser-diode-based SS-interferometer system (SS=swept source), for a wide range of application suitable for use in ophthalmology, for example for imaging and for determining biometric measurement values of the eye. In a method according to the invention, by application of periodic current modulation, the operation of single semiconductor laser diode is designed such that a highly coherent spectral laser line can be adjusted with a highest possible repetition rate over a wide wavelength range. The parameters: center wavelength, sweep rate, sweep range, optical power in the eye and coherence length are adjusted such that the method is suitable for imaging and biometric applications via whole-eye scans. A semiconductor-laser-diode-based SS-interferometer system is provided, for biometric measuring of the eye. Embodiments are based for example on optical, coherence tomographic scan images. Applications lie in ophthalmological diagnostics, treatment and the preparation of surgical procedures and follow-up thereof.

Method for controlling a semiconductor-laser-diode-based SS-interferometer system

A device for determining biometric variables of the eye, as are incorporated in the calculation of intraocular lenses including a multi-point keratometer and an OCT arrangement. The keratometer measurement points are illuminated telecentrically and detected telecentrically and the OCT arrangement is designed as a laterally scanning swept-source system with a detection region detecting the whole eye over the whole axial length thereof. Illumination points are arranged in three rings concentrically around an instrument axis; and the three rings include a first ring, a second ring and a third ring and the illumination points on the first ring and the third ring are rotated in relation to the illumination points on the second ring such that each of the illumination points on the first ring is on a common radial with one of the illumination points on the third ring and each of the illumination points on the second ring is not on the common radial.

Device for reliably determining biometric measurement variables of the whole eye

A device for determining biometric variables of the eye, as are incorporated in the calculation of intraocular lenses including a multi-point keratometer and an OCT arrangement. The keratometer measurement points are illuminated telecentrically and detected telecentrically and the OCT arrangement is designed as a laterally scanning swept-source system with a detection region detecting the whole eye over the whole axial length thereof. The multi-point keratometer ensures that a sufficient number of keratometer points are available for measuring the corneal surface. By contrast, telecentricity ensures that the positioning inadequacies of the measuring instrument in relation to the eye to be measured do not lead to a local mismatch of the reflection points. The swept-source OCT scan detects the whole eye over the length thereof so that both anterior chamber structures and retina structures can be detected and a consistent whole eye image can be realized.

A method for measuring the geometric parameters of the eye. These measurements, known by the term biometrics, are particularly significant for the calculation of intraocular lenses after previous refractive cornea surgery. OCT images and other images are recorded simultaneously, the intensity of the reflected light generated during the OCT image recordings being lower by a factor of 2, by a factor of 10 or by a factor of 100, than the intensity of the illumination light of the other image recordings. The solution provides a method for producing other image recordings, in addition to OCT recordings, in the form of representations of the sclera or of the fundus, or keratometric, topographic or biometric measurements, or even short image sequences, for instance, while aligning the device with the eye.

Method for producing OCT images and other images of an eye including reducing the intensity of reflected light

Optimized device for swept source optical coherence domain reflectometry and tomography. In the coherence-optical device, light, with the aid of an interferometer, is used for distance-measuring and imaging purposes on reflecting and scattering areas of the human eye. The optimized device according to the invention consists of includes a tunable light source, matched to the sought-after measurement region ZOCT, with a resonator length LR, an interferometric measurement arrangement, a data capturing unit for capturing the light portions scattered back from the sample and a data processing unit. Here the resonator length LR of the tunable light source is matched not only to the sought-after measurement region ZOCT, but also to the entire interferometric measurement arrangement such that disturbance points present in the interferometric measurement arrangement cannot create disturbance signals in the sought-after measurement region ZOCT.

Optimized device for swept source optical coherence domain reflectometry and tomography

A method for measuring the axial length of an eye using optical coherence tomography, during which a plurality of A-scans of the OCT measurement are combined to an axial length, taking into account the alignment with which they were obtained, and taking into account the topography of the cornea. The distance of the front of the cornea from the retina is determined using OCT while measuring or controlling the alignment of the measuring device to the eye in that the topography of the front of the cornea is measured or made available. The calculation of an axial length from an A-scan of the OCT takes into account a corneal topography registered to the A-scans and is the basis for an intraocular lens calculation. The invention exhibits an increased tolerance range with regard to an imprecise alignment of the measuring device to the eye.

Method for measuring an eye

A short coherence interferometer for measuring several axially spaced-apart regions of a sample, especially of an eye, which has a measuring optical path, through which the measuring radiation falls on the sample, a tunable interferometer for the axial, relative retardation of parts of the radiation, wherein the axial relative retardation is assigned to the axial spacing of the regions and a detector for producing an interference signal from interfering measurement radiation, scattered or reflected back from the sample as sample radiation. The tunable interferometer divides the sample radiation into two parts, which are axially relatively retarded and superimposed so as to interfere. During the superimposition, the tunable interferometer forms individual radiations, which represent quadrature components of the sample radiation, and the detector detects the individual radiations.

Short coherence interferometry for measuring distances

A device for swept-source optical coherence domain reflectometry (SS OCDR) on moveable samples, particularly human eyes, for obtaining A-scans, having a measuring range according to the sample length and having a laser light source which can be adjusted by a main wave number kand at least one receiver for the light dissipated from the sample, wherein the sample is illuminated on the sample surface by a measurement beam having a diameter D by way of a coupling device. The light source has a spectral line width of &#x3b4;k&#x3c;168 mand the adjustment of the light source is carried out in &#x3c4;&#x3c;44 s/(D*k).

Device for swept source optical coherence domain reflectometry

An ophthalmological measuring system, for obtaining biometric data of an eye, provided with the necessary calibration and check devices for monitoring the functionality and the calibration status. The ophthalmological measuring system includes an illumination source for illuminating an eye with light and with a sensor for recording and analyzing back-scattered or reflected light components and a controller. At least one calibration and check system integrated in the ophthalmological measuring system for monitoring the functional and calibration status is provided. A device is also provided which houses the calibration and test structures and which reads off the individual physical data therefrom by an interface. The ophthalmological measuring system is in particular provided for determining biometrical data but can also be used for ophthalmological, dermatological or other devices which require calibration and/or functional checking at regular intervals.

Ophthalmological measuring system and method for calibrating and/or adjusting the same

A method for reliably determining the axial length of an eye uses optical coherence tomography (OCT), where the eye is aligned with a fixation mark so that the optical axis of the measuring instrument coincides at least approximately with a visual axis of the eye. The axial length is determined from at least one B-scan taken in an initial AS mode (anterior segment mode) and the axial length is also determined from at least one B-scan taken in a second RS mode (retina segment mode). A resultant reliable axial length of the eye is determined using the axial lengths from the AS and RS modes, where available and where possible, or the process is ended without a resultant axial length.

Process for reliably determining the axial length of an eye

An ophthalmological measuring system for determining distances and/or for tomographic imaging of ocular structures, based on an OCT method. The measuring system includes a light source with a spectral centroid (&#x3bb;), an interferometric measuring device, a scanner system, which in addition to the lateral deflection of the sample beam also has axial modulations with a frequency (f) in the sample arm, and a control and evaluation unit. The scanner performs a lateral, two-dimensional deflection of the sample beam with the aid of one or even two separate mirror elements and can in particular have axial modulation amplitudes z&#x3e;&#x3e;&#x3bb;/2. The system can also be used for scanner systems in other fields that use an OCT method, in particular a swept-source OCT method.

OCT-based ophthalmological measuring system

An optical deflection unit for targeted radiation, e.g., produced by laser or superluminescent diodes, in scanning, ophthalmological measuring and therapy systems, comprises a deflection mirror, a position sensor and a control unit, which form a control circuit for minimizing the deviation of the actual positions, detected by the position sensor, from the desired positions of the deflection mirror, whereby the optical deflection unit comprises a deflection mirror, oscillatingly movable by means of non-contacting electromagnetic drives around at least one rotation axis, and which is positioned in the direction of the, at least, one rotation axis between at least two bearings. The optical deflection unit is designed may also be used for beam guidance in high and ultrahigh vacuum installations, such as UV and EUV exposure installations for semiconductor lithography.

Growing community of inventors

Schmoelln, Germany

Ralf Ebersbach