Carl Zeiss Jena Gmbh

Carl Zeiss Meditec Ag

Other

Adolf Friedrich Fercher

Roland Barth

Rainer Leitgeb

Thomas K Bende

Martin Hacker

Ingo Koschmieder

Roland Bergner

Rudolf Von Buenau

Wilfried Bissmann

Ralf Ebersbach

Benedikt Jean

Branislav Grajciar

Jean Benedikt

Franz Lexer

Harald Sattmann

Rudolf Von BÜNAU

Measurement of intraocular lengths by dual-beam Fourier low-coherence interferometry on the basis of Fresnel-zone-type space-time domain interferograms of the Purkinje-Sanson reflexes. The eye is illuminated by parallel, monochromatic dual beams having wavelengths which differ in temporal sequence. Wavelength spectra of space-time domain interferograms are imaged onto a photodetector array and registered. Viewing direction and position of the eye are fixed by optical aids and are monitored by acoustic and optical aids. A zoom optical unit in the output beam of the ophthalmological interferometer makes it possible, by simple focusing, to image virtual Fresnel-zone-type space-time domain interferograms from contrast-optimized positions onto the photodetector array or onto an image intensifier that is arranged in front of the photodetector array such that the position-dependent size change of the space-time domain interferograms is compensated by the scale change of this imaging.

Ophthalmological length measurement by means of dual-beam space-time domain wavelength tuning low-coherence interferometry

A device for performing distance measurements on an eye. The device includes an interferometer, focuses at least one measurement beam records backscattered radiation and interferometrically generates a measurement signal displaying structures of the eye by time-domain, spectral-domain or Fourier-domain coherence reflectometry, has an adjustment apparatus for laterally and/or axially displacing the focus in the eye or for varying a polarization state of the measurement beam and has a control apparatus which actuates the interferometer, wherein the control apparatus generates a plurality of A-scan individual signals from the backscattered radiation, combines these to an A-scan measurement signal and actuates the adjustment apparatus for displacing the position of the focus or for varying the polarization while recording the backscattered radiation from which the control apparatus generates the A-scan individual signals is being recorded.

Optical coherence reflectometry with depth resolution

A device for the interferometric measurement of a sample, in particular the eye, including an interferometer arrangement with a first measurement beam path, through which a measurement beam falls onto the sample, and a first reference beam path, through which a reference beam runs, which is applied to the measuring beam for interference. The interferometer arrangement includes a second measuring beam path and/or second reference beam path. The optical path lengths of the second measuring beam path and/or second reference beam path are different from one of the first beam paths. The wave length difference is selected according to a distance of two measuring areas which are arranged at a distance in the depth direction of the sample.

Interferometric sample measurement

Apparatus and method for interferometric measurement of a sample

The present invention is directed to an ophthalmologic measurement method which can depict three-dimensional structures of the interfaces of an eye by short-coherence interferometry based on reference points. For this purpose, the pupil is illuminated at a plurality of points by a short-coherence illumination source. The measurement beam reflected at these points by the interfaces and surfaces of the eye is superimposed with a reference beam. The measurement data which are generated in this way are spectrally split by a diffraction grating, imaged on a two-dimensional detector array and conveyed to a control unit which determines a three-dimensional structure of all intraocular interfaces and surfaces of the eye. In the suggested Fourier domain OCT method, the depiction of three-dimensional structures is preferably carried out by spline surfaces or polygon surfaces. In doing so, it is possible to determine the depth positions of the measurement beams in many points of the pupil with a single recording of the array camera in that the pupils are illuminated by a diaphragm grid and the reference mirror contains a periodic phase grid.

Fourier-domain OCT ray-tracing on the eye

Two problems arise when measuring length at the eye by short-coherence interferometry. First, the measurement focus and coherence window usually do not coincide. Second, the scanning process along the eye axis is time-consumin g. Both result in poor signal quality and inaccurate measurements. The present application is directed to a short-coherence interferometer in which a right-angle mirror and focusing optics jointly carry out a periodic back-and-forth movement in such a way that the measurement beam focus which is generated by the focusing optics and imaged on the eye by relay optics is moved synchronously with the coherence window from the cornea along the optic axis of the eye to the fovea centralis. Further, different path lengths are generated in the measurement beam path and reference beam path by means of a plurality of reflectors, so that the scanning process is limited to distances which are smaller than the optical length of the eye. The present invention is advantageously implemented using on a fiber-optic interferometer. According to the invention, the reference interferometer arm and measurement interferometer arm are combined with the arms of a fiber-optic interferometer.

Short-coherence interferometric measurement of length on the eye

The invention is directed to a device for determining the thickness, distance and/or profile of areas of a transparent and/or diffuse object that are spaced apart, in particular for measuring distances in the eye. In the device for determining position using an interferometer arrangement based on the Michelson principle, a scanning unit is arranged for the change in path length in the reference beam or measurement beam path. The scanning unit comprises a scan table which is movable translationally in corresponding guides, the movement direction enclosing an angle &#x3b1; to the reference beam. At least two reference mirrors having a distance d in direction of the reference beam and slightly overlapping laterally are arranged on the scan table so that during the oscillating movement of the scan table carried out by a motor the reference beam is reflected in itself first by the first reference mirror and then by the second reference mirror.

Device for determining the position of spaced-apart areas in transparent and/or diffuse objects

An apparatus (') for detecting the surface topography of a cornea () of an eye () by dynamic or static projection of a pattern onto the surface of the cornea and detection of the pattern reflected by the cornea, providing preferably simultaneous detection of at least one optical property of a layer disposed beneath the cornea.

Method and an apparatus for the simultaneous determination of surface topometry and biometry of the eye

A method and/or arrangement for compensating the dispersion in signals of short-coherence interferometers and/or OCT interferometers, wherein the effect of the dispersion is eliminated by subsequent compensation in that the interferometer signal is correlated with a spatially variant correlation core which corresponds along the measurement axis in z-direction to an interferometer signal of an individual light-reemitting location with the same dispersion which is punctiform in z-direction.

Numerical a posteriori dispersion compensation in PCI measurement signals and OCT A-scan signals with spatially variant correlation core

An airbag cover is defined by a predetermined breaking line which is introduced into a shaped flat material in a recessed manner. The recesses are achieved by removing material by means of laser radiation. According to the invention, the flat material is provided with a barrier layer. The barrier layer, by reason of its material properties, has greater resistance to removal of material by laser action than the material of the rest of the flat material. The recesses made by removing material extend along the predetermined breaking line in the flat material up to the barrier layer. The barrier layer makes it possible to produce a predetermined breaking line by means of laser machining which allows an exact residual wall thickness of the airbag cover in the area of the predetermined breaking line, so that the tearing strength can be adjusted very accurately, which is critically important for a reliable deployment of an airbag. Further, a method for the efficient production of an airbag cover of this type is indicated.

Optical coherence interferometry and coherence tomography with spatially partially coherent light sources

The invention is directed to the detection and imaging of the internal geometry of the eye, particularly of the important components for imaging in the eye such as the cornea, lens, vitreous body and retinal surface, by multichannel short coherence interferometry. A method and arrangement for obtaining topograms and tomograms of the eye structure by many simultaneously recorded interferometric depth scans through transversely adjacent points in the pupil using spatially coherent or spatially partially coherent light sources. The depth scan is carried out by changing the optical length of the interferometer measurement arm by means of a retroreflector. By continuously displacing the retroreflector, the z-position of the light-reemitting point in the eye can be determined by means of the occurring interference. It is possible to record depth scans simultaneously through the use of spatially coherent or spatially partially coherent light beams comprising a plurality of partial beams.

Optical multiplex short coherence interferometry on the eye

Topographic measurement of eye structures based on short coherence interferometry is the subject of the invention. The problem occurring in this connection is that longitudinal and transverse eye movements during signal registration lead to errors in the measured structure. The influences of longitudinal eye movements are compensated in that the reference beam, independent from the measurement beam, is directed to the corneal vertex and is reflected at the latter. The influences of longitudinal eye movements are minimized in that the transverse position of the eye is monitored by means of a direction-dependent registration of the light reflected at the corneal vertex by means of a diode array or a four-quadrant diode and transverse misalignment is detected and compensated.

Arrangements for coherence topographic ray tracing on the eye

An apparatus ( &prime;) for detecting the surface topography of a cornea ( ) of an eye ( ) by dynamic or static projection of a pattern onto the surface of the cornea and detection of the pattern reflected by the cornea, providing preferably simultaneous detection of at least one optical property of a layer disposed beneath the cornea.

Method and apparatus for the simultaneous determination of surface topometry and biometry of the eye

An arrangement is provided for optical surface profile measurement and for obtaining optical sectional images of transparent, partially transparent and opaque objects by the spectral interferometric OCT method. In the spectral interferometric OCT method, the depth position of the object locations from which light is diffusely reflected is given by the light diffusely reflected by the object through a Fourier transform. Because of the path difference between the object light and reference light which is required for this purpose, large spatial frequencies occur in the spectrum which impair the resolution capacity of this method. According to the invention, the reference light is used to measure the phase of the wavelength spectrum by use of discrete phase displacements from the measured spectral intensities. This is also possible when the path difference between the object light and reference light is zero and a worsening of resolution therefore does not occur in this case.

Arrangement for spectral interferometric optical tomography and surface profile measurement

A dynamic optical path length modulator for optical interferometry, holography and tomography is disclosed. The optical path length in a beam path is changed in that the light beam in question is guided through a double mirror arrangement which is formed of two plane mirrors which are parallel to one another and are rotatable about a common axis. A path length-dependent dispersion of any desired magnitude can be introduced into the beam path by the arrangement of plane plates and prisms.

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Vienna, Austria

Adolf Friedrich Fercher