System and Method for Optical Coherence Tomography

Abstract

The invention relates to a system and to a corresponding method for optical coherence tomography having an interferometer ( 10 ) for emitting light with which a specimen ( 1 ) is irradiated, the interferometer ( 10 ) comprising a beam splitter ( 13 ) and at least one reflector ( 12 ) the optical distance (I) of which from the beam splitter ( 13 ) can be changed by an optical path (L), and a detector ( 30 ) with a first number of detector elements arranged in a first area for collecting light which is reflected by the specimen ( 1 ). In order to be able to record images of a specimen, in particular in real time, more simply and quickly, the system is operated in a first mode in which light reflected by the specimen ( 1 ) is only collected by a second number of detector elements of the detector ( 30 ) and converted into corresponding detector signals, the second number of detector elements being smaller than the first number of detector elements.

1 - 24 . (canceled) 
     
     
         25 . A system for optical coherence tomography having
 an interferometer for emitting light with which a specimen is irradiated, the interferometer comprising a beam splitter and at least one reflector the optical distance of which from the beam splitter can be changed by an optical path, and   a detector with a first number of detector elements arranged in a first area for collecting light which is reflected by the specimen, wherein   the optical distance between the reflector and the beam splitter is changeable by an optical path which is substantially greater than the average wavelength (λ0) of light injected into the interferometer, and   the interferometer comprises a further reflector the optical distance of which from the beam splitter can be changed by a further optical path which is maximum ten times the average wavelength (λ0) of the light injected into the interferometer.   
     
     
         26 . The system according to  claim 25 , wherein the system can be operated in a first mode in which light reflected by the specimen is only collected by a second number of detector elements of the detector and converted into corresponding detector signals, the second number of detector elements being smaller than the first number of detector elements. 
     
     
         27 . The system according to  claim 26 , wherein the second number of detector elements is maximum a quarter of the first number of detector elements. 
     
     
         28 . The system according to  claim 27 , wherein the second number of detector elements is arranged in a second area which forms a coherent partial area of the first area. 
     
     
         29 . The system according to  claim 28 , wherein the first area has a first width and a first length and the second area has a second width and a second length, the first and the second length are substantially identical and the second width is smaller than the first width. 
     
     
         30 . The system according to  claim 26 , wherein during the change of the optical distance between the reflector and the beam splitter by the optical path the light reflected by the specimen is collected a number of times only by the second number of detector elements of the detector, by means of which a number of two-dimensional depth sections are obtained by a spatial element of the specimen. 
     
     
         31 . The system according to  claim 25 , wherein the system can be operated in a second mode in which during the change of the optical distance between the further reflector and the beam splitter the light reflected by the specimen is collected by the detector elements of the detector a number of times by means of which a two-dimensional section through a spatial element of the specimen is obtained at a depth of the specimen pre-specified by the optical distance between the reflector and the beam splitter. 
     
     
         32 . The system according to  claim 25 , wherein the system can be operated in a third mode in which during the change of the optical distance between the reflector and the beam splitter by the optical path the light reflected by the specimen is collected by the detector elements of the detector a number of times, by means of which the light reflected by a number of two-dimensional sections is collected at different depths of the specimen. 
     
     
         33 . The system according to  claim 25 , wherein the system has a specimen objective by means of which light emitted by the interferometer is focused into a focus lying on or in the specimen, wherein during the change of the optical distance between the reflector and the beam splitter the light respectively reflected at a number of different depths of the specimen is collected by the detector and at the same time the imaging properties of the specimen objective are controlled so that the focus comes within the range of the respective depth of the specimen. 
     
     
         34 . The system according to  claim 25 , wherein the intensity of light which is injected into the interferometer or emitted by the interferometer is modulated with a modulation frequency. 
     
     
         35 . The system according to  claim 34 , wherein the modulation frequency is not equal to the Doppler frequency, the Doppler frequency being given by twice the ratio of the speed of the change of the optical distance between the reflector or the further reflector and the beam splitter by the optical path or the further optical path to the mean wavelength (λ 0 ) of the light injected into the interferometer. 
     
     
         36 . The system according to  claim 25 , wherein a detector system is provided, the detector system comprising the detector, the sensitivity of the detector system for the light reflected by the specimen and impinging on the detector being modulated with a modulation frequency. 
     
     
         37 . The system according to  claim 36 , wherein the modulation frequency is not equal to the Doppler frequency, the Doppler frequency being given by twice the ratio of the speed of the change of the optical distance between the reflector or the further reflector and the beam splitter by the optical path or the further optical path to the mean wavelength (λ 0 ) of the light injected into the interferometer. 
     
     
         38 . The system according to  claim 25 , wherein the system can be operated in a second mode in which during the change of the optical distance between the further reflector and the beam splitter the light reflected by the specimen is collected by the detector elements of the detector a maximum five times by means of which a two-dimensional section through a spatial element of the specimen is obtained at a depth of the specimen pre-specified by the optical distance between the reflector and the beam splitter. 
     
     
         39 . A method for optical coherence tomography wherein
 light is emitted by an interferometer with which a specimen is irradiated, the interferometer comprising a beam splitter and at least one reflector the optical distance of which from the beam splitter is changeable, and   light reflected by the specimen is collected by a detector which comprises a first number of detector elements arranged in a first area, wherein   the optical distance between the reflector and the beam splitter is changed by an optical path which is substantially greater than the average wavelength (λ 0 ) of light injected into the interferometer, and   the optical distance of a further reflector from the beam splitter is changed by a further optical path which is maximum ten times the average wavelength (λ 0 ) of the light injected into the interferometer.