Apparatus and method for measuring an optical break-through in a tissue

Abstract

The invention relates to a device for measuring an optical penetration that is triggered in a tissue underneath the tissue surface by means of therapeutic laser radiation which a laser-surgical device concentrates in a treatment focus located in said tissue. The inventive device is provided with a detection beam path comprising a lens system which couples radiation emanating from the tissue underneath the tissue surface into the detection beam path. A detector device generating a detection signal which indicates the spatial dimension and/or position of the optical penetration in the tissue is arranged downstream of the detection beam path.

1 .- 31 . (canceled) 
     
     
         32 . A device for measuring an optical break-through which is created in a tissue, beneath a tissue surface, by treating laser radiation which a laser surgical unit focuses into a treatment focus, said focus being located in the tissue wherein said device comprises a detection beam path comprising optics, wherein the optics couple radiation emitted by the tissue from beneath the tissue surface, into the detection beam path, and a detector unit is arranged following the detection beam path, said detector unit generating a detection signal which indicates the spatial extent, position or both of the optical break-through in the tissue. 
     
     
         33 . The device as claimed in  claim 32 , further comprising an illumination radiation source, which directs illumination radiation into the tissue. 
     
     
         34 . The device as claimed in  claim 33 , wherein the illumination radiation source supplies the treating laser radiation. 
     
     
         35 . The device as claimed in  claim 33 , wherein the illumination radiation source and the detection beam path are part of an interferometer structure. 
     
     
         36 . The device as claimed in  claim 35 , wherein the interferometer structure comprises a measuring arm and an adjustable reference arm and the illumination radiation has a coherence length, in the direction of light propagation and in which the resolution at which the detection signal indicates the spatial extent depends on the coherence length, and wherein interference appears only, if the lengths of the measuring arm and of the reference arm differ by no more than the coherence length. 
     
     
         37 . The device as claimed in  claim 35 , wherein the illumination source radiation focuses the illumination radiation into an illumination focus located in the tissue, wherein the position of the illumination focus is adjustable to generate the detection signal. 
     
     
         38 . The device as claimed in  claim 37 , wherein the illumination radiation is coupled into a light path of the treating laser radiation, and further comprising adjustable optics by which the divergence of the illumination radiation is changeable without changing the divergence of the treating laser radiation. 
     
     
         39 . The device as claimed in  claim 32 , wherein the detector unit detects the radiation emitted by the tissue by confocal imaging. 
     
     
         40 . The device as claimed in  claim 39 , wherein the detector unit generates the detection signal by adjusting the focus of the confocal imaging, preferably along a ray direction of the treating laser radiation. 
     
     
         41 . The device as claimed in  claim 39 , wherein the optics of the detection beam path have certain light dispersing properties, so that they comprise different focal points during the confocal imaging for different spectral regions, wherein the detector unit effects a spectrally selective detection of the radiation recorded in the confocal imaging, to generate the detection signal. 
     
     
         42 . The device as claimed in  claim 41 , further comprising a multi-channel spectrometer for picking up radiation behind a pinhole. 
     
     
         43 . The device as claimed in  claim 33 , wherein the source of illumination radiation comprises a plurality of partial radiation sources, which are individually operable and have different spectral properties, so that spectral selective sensing is obtained by sequentially operating said partial radiation sources. 
     
     
         44 . The device as claimed in  claim 32 , wherein the detection beam path has an optical axis which is located obliquely to an optical axis of the treating laser radiation or of illumination radiation. 
     
     
         45 . The device as claimed in  claim 33 , wherein the source of illumination radiation causes a slit illumination of the tissue. 
     
     
         46 . The device as claimed in  claim 44 , further comprising a scanning unit by which the position of the optical axis of the detection beam path is adjustable relative to the optical axis of the treating laser radiation or of the illumination radiation. 
     
     
         47 . The device as claimed in  claim 32 , wherein the detector unit determines a measure of the spatial extent, the position or both of individual scattering centers, which are generated by the break-through. 
     
     
         48 . The device as claimed in  claim 32 , wherein the detection signal indicates a diameter of a plasma bubble, which was generated by an optimal break-through. 
     
     
         49 . The device as claimed in  claim 32 , further comprising a scanning device for scanning the tissue. 
     
     
         50 . A method of measuring an optical break-through which is created in a tissue, beneath a tissue surface, by treating laser radiation comprising the steps of:
 detecting radiation emitted by the tissue from beneath the tissue surface; and   determining a spatial extent of the optical break through, a position of the optical break through or both of the foregoing from detection of the emitted radiation.   
     
     
         51 . The method as claimed in  claim 50 , wherein the spatial extent, the position or both of scattering centers generated by the optical break-through is determined. Application No. 
     
     
         52 . The method as claimed in  claim 50 , wherein observation radiation is directed into the tissue, and radiation emitted by the tissue in the form of back-reflection is evaluated. 
     
     
         53 . The method as claimed in  claim 51 , wherein the radiation emitted by the tissue is interferometrically detected. 
     
     
         54 . The method as claimed in  claim 53 , wherein a position of the radiation emitted by the tissue along an optical axis of detection is determined from occurring interference. 
     
     
         55 . The method as claimed in  claim 50 , wherein the radiation emitted by the tissue is detected by confocal imaging and the spatial extent is determined by adjusting a focus of said confocal imaging. 
     
     
         56 . The method as claimed in  claim 55 , wherein different spectral focal points are generated in confocal imaging by dispersive optics and radiation recorded behind a pinhole is spectrally evaluated. 
     
     
         57 . The method as claimed in  claim 52 , wherein spectrally different radiation is sequentially directed toward the tissue and the radiation emitted by the tissue is sequentially recorded. 
     
     
         58 . The method as claimed in  claim 50 , wherein the emitted radiation is detected along an optical axis which is oblique relative to an optical axis along which the treating laser radiation or observation radiation is directed into the tissue. 
     
     
         59 . The method as claimed in  claim 58 , wherein the treatment radiation is directed into the tissue as a slit-shaped beam. 
     
     
         60 . The method as claimed in  claim 58 , wherein an angle between the optical axis of detection and the optical axis of irradiation is adjusted to obtain information on the spatial extent of the interaction. 
     
     
         61 . The method as claimed in  claim 50 , wherein a measure of the spatial extent of individual scattering centers of the optical break-through is generated. 
     
     
         62 . The method as claimed in  claim 61 , wherein a diameter of a plasma bubble is determined.