Pulsed light source for removing biological tissue

Abstract

A pulsed light source for cutting away biological tissue has a control unit that controls the light source in such a way that the light source supplies a series of pulses of predetermined duration and radiation intensity. The control unit may be operated to cause the light source to supply short pulses ( 10 ) at a predetermined and/or controllable rate of repetition with a radiation intensity sufficient to cut away the tissues, and radiation followed by light emission ( 11 ) or the like with a radiation intensity that is not sufficient to cut away the tissues but is sufficient to generate heat.

1 . Pulsed light source for removing biological tissue, having a control unit for controlling the light source in such a way that it supplies a sequence of pulses in each case with a predetermined duration and irradiation intensity, characterized in that the control unit can be operated in such a way that the light source supplies at a predetermined and/or controllable repetition rate short pulses ( 10 ) with an irradiation intensity and irradiation sufficient for removing tissue and a respectively subsequent light radiation ( 10   b;    11 ;  12 - 14 ) with an irradiation intensity and/or irradiation which is not sufficient for removing tissue, but produces a thermal effect.  
     
     
         2 . Light source according to    claim 1   , characterized in that the light source supplies at the repetition rate pulses which in each case comprise a first pulse portion ( 10   a ) of short duration with an irradiation intensity and irradiation sufficient for removing tissue and a subsequent pulse portion ( 10   b ) of which the irradiation intensity is modulated in such a way that, the removal is stopped after the first pulse portion ( 10   a ) and the tissue is only heated during the second pulse portion ( 10   b ).  
     
     
         3 . Light source according to    claim 1   , characterized in that the light source supplies at the repetition rate sequences of pulses which comprise at least one short first pulse ( 10 ) with an irradiation intensity and irradiation sufficient for removing tissue and at least one further pulse ( 11 ;  12 - 14 ) with an irradiation intensity and/or irradiation which is not sufficient for removing tissue, but leads to a thermal effect.  
     
     
         4 . Light source according to one of    claims 1    to    3   , characterized in that the short pulses ( 10 ) or pulse portions ( 10   a ) produce a removal of tissue with little damage and only little coagulation of the marginal regions of the removal.  
     
     
         5 . Light source according to one of    claims 1    to    4   , characterized in that the short pulses ( 10 ) or pulse portions ( 10   a ) have a high irradiation intensity and the emitted light has a high absorption in the tissue.  
     
     
         6 . Light source according to one of the preceding claims, characterized in that the light source through is a laser emitting ultraviolet or infrared light.  
     
     
         7 . Light source according to    claim 6   , characterized in that the laser is a pulsed erbium, holmium, thulium, CO 2  or excimer laser.  
     
     
         8 . Light source according to one of the preceding claims, characterized in that the irradiation applied to the tissue surface with each short pulse ( 10 ) or pulse portion ( 10   a ) lies in the range from 1 to 250 Jcm −2  per pulse or pulse portion.  
     
     
         9 . Light source according to one of the preceding claims, characterized in that each short pulse ( 10 ) or pulse portion ( 10   a ) has a power of more than 500 watts and a duration of 50 to 1000 microseconds.  
     
     
         10 . Light source according to one of the preceding claims, characterized in that the energy of the further pulses ( 11 ;  12 - 14 ) or of the subsequent pulse portion ( 10   b ) is in each case dimensioned in such a way that, given a predetermined size of the irradiation zone, the removal threshold of the tissue is not reached.  
     
     
         11 . Light source according to one of the preceding claims, characterized in that the at least one further pulse ( 11 ) has an irradiation intensity decreasing with time.  
     
     
         12 . Light source according to one of claims  1 ,  2  and  4  to  10 , characterized in that the subsequent pulse portion ( 10   b ) initially has an irradiation intensity increasing with time and then subsequently decreasing.  
     
     
         13 . Light source according to one of    claims 1    to    11   , characterized in that the individual successive further pulses ( 12 - 14 ) of a sequence of pulses in each case have a decreasing irradiation intensity, but an increasing pulse duration and in that, given a predetermined size of the irradiation zone, the energy content of each and every one of these pulses lies below the removal threshold value.  
     
     
         14 . Light source according to one of    claims 3    to    11    and    13   , characterized in that each sequence of pulses has a predetermined duration.  
     
     
         15 . Light source according to one of the preceding claims, characterized in that the energy content of the pulse ( 11 ) following the short pulse ( 10 ) or pulse portion ( 10   a ), or of the following series of pulses ( 12 - 14 ) or of the subsequent pulse portion ( 10   b ), is sufficient for coagulation of the tissue.  
     
     
         16 . Light source according to one of the preceding claims, characterized in that the control unit controls the energy content of the pulse ( 11 ) following the short pulse ( 10 ) or pulse portion ( 10   a ), or of the following series of pulses ( 12 - 14 ) or of the subsequent pulse portion ( 10   b ) and/or the intervals between successive pulses in dependence on a measurement of the surface temperature of the tissue.