Measuring arrangement for examining a subject with visible, NIR or IR light
First Claim
Patent Images
1. An apparatus for optically analyzing tissue in vivo comprising:
- means for directing a measuring chirp signal at a tissue-containing subject, said measuring chirp signal being a coherent optical signal of light selected from the group consisting of visible, NIR and IR light, a part of said measuring chirp signal emerging from said subject after interacting therein with tissue to be analyzed and forming an emerging signal;
means for generating a reference chirp signal having a defined phase relationship to said measuring chirp signal;
means for superimposing said emerging signal with said reference chirp signal to form a superposition signal having sets of beats, each set of beats having a respective beat frequency;
filter means, for receiving said superposition signal and having a transmission range with an upper limit frequency, for generating from said superposition signal a filtered signal having at least one beat frequency within said transmission range; and
means for dimensioning parameters including the transit time of said measuring chirp signal outside said subject, the transit time of said reference chirp signal, and said upper limit frequency of said filter means for causing said filtered signal to represent substantially only parts of said emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length.
1 Assignment
0 Petitions
Accused Products
Abstract
An apparatus for examining tissue in vivo by means of the optical properties of the tissue generates a measuring chirp signal which is introduced into a tissue-containing subject as a coherent optical chirp signal. The parts of the measuring chirp signal emerging from the subject are superimposed with a reference chirp signal to form a superposition signal that is supplied to a filter that only allows those parts of the superposition signal to pass that represent those parts of the measuring chirp signal emerging from the subject which have traversed a defined, optical path length within the subject.
-
Citations
80 Claims
-
1. An apparatus for optically analyzing tissue in vivo comprising:
-
means for directing a measuring chirp signal at a tissue-containing subject, said measuring chirp signal being a coherent optical signal of light selected from the group consisting of visible, NIR and IR light, a part of said measuring chirp signal emerging from said subject after interacting therein with tissue to be analyzed and forming an emerging signal; means for generating a reference chirp signal having a defined phase relationship to said measuring chirp signal; means for superimposing said emerging signal with said reference chirp signal to form a superposition signal having sets of beats, each set of beats having a respective beat frequency; filter means, for receiving said superposition signal and having a transmission range with an upper limit frequency, for generating from said superposition signal a filtered signal having at least one beat frequency within said transmission range; and means for dimensioning parameters including the transit time of said measuring chirp signal outside said subject, the transit time of said reference chirp signal, and said upper limit frequency of said filter means for causing said filtered signal to represent substantially only parts of said emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
-
-
35. An apparatus for optically analyzing tissue comprising:
-
a coherent light source for generating a coherent optical chirp signal of light selected from the group consisting of visible, NIR and IR light; beam splitter means for splitting said optical chirp signal into a measuring chirp signal and a reference chirp signal having a defined phase relationship to said measuring chirp signal; a first group of optical fibers, having respectively different combinations of refractive index and length, said optical fibers in said first group being used one at a time to conduct said measuring chirp signal from said beam splitter means to a tissue-containing subject, a part of said measuring chirp signal emerging from said subject after interacting with tissue therein to be analyzed and forming an emerging signal; means for superimposing said emerging signal with said reference chirp signal to form an optical superposition signal having sets of beats, each set of beats having a respective beat frequency; a second group of separate optical fibers, having respectively different combinations of refractive index and length, said optical fibers in said second group being selected for use one at time to conduct said reference chirp signal from said beam splitter means to said means for superimposing; a third group of separate optical fibers, having respectively different combinations of refractive index and length, said optical fibers in said second group being selected for use one at a time to conduct said emerging signal from said subject to said means for superimposing; detector means for converting said optical superposition signal into an electrical superposition signal; filter means, for receiving said electrical superposition signal and having a transmission range with an upper limit frequency, for generating from said superposition signal a filtered signal having at least one beat frequency within said transmission range; and means for selecting said upper limit frequency, in combination with the transit time of said measuring chirp signal outside said subject defined by the selected one of said optical fibers in said first and third groups and the transit time of said reference chirp signal defined by the selected one of said optical fibers in said second group, for causing said filtered signal to represent substantially only parts of said emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length. - View Dependent Claims (36, 37, 38, 39)
-
-
40. An apparatus for optically analyzing tissue in vivo comprising:
-
a coherent light source generating a coherent optical chirp signal of light selected from the group consisting of visible, NIR and IR light, said optical chirp signal propagating along a first propagation path; a semi-reflective mirror disposed in said first propagation path at an angle deviating from 90°
which splits said optical chirp signal into a measuring chirp signal which continues to propagate along said first propagation path toward a tissue-containing subject, and a reference chirp signal propagating along a second propagation path, different from said first propagation path, a part of said measuring chirp signal emerging from said subject after interacting with tissue therein to be analyzed and forming an emerging signal propagating back along said first propagation path toward said semi-reflective mirror;a fully-reflective mirror disposed a distance from said semi-reflective mirror in said second propagation path which directly and fully reflects said reference chirp signal back along said second propagation path toward said semi-reflective mirror so that said reference chirp signal has a defined phase relationship to said measuring chirp signal; said fully-reflected reference chirp signal passing through said semi-reflective mirror and said emerging signal being deflected by said semi-reflective mirror so that both signals are superimposed forming an optical superposition signal having sets of beats, each set of beats having a respective beat frequency; detector means, for receiving said optical superposition signal, for generating a corresponding electrical superposition signal; filter means, supplied with said electrical superposition signal and having a transmission range with an upper limit frequency, for generating from said superposition signal a filtered signal having at least one beat frequency within said transmission range; first adjustment means for adjusting the distance between said semi-reflective mirror and said fully reflective mirror; second adjustment means for adjusting the distance between said semi-reflective mirror and said examination subject; third adjustment means for adjusting the distance between said semi-reflective mirror and said detector means; means for selecting said upper limit frequency of said filter means; and said first, second and third adjustment means and said means for adjusting said upper limit frequency forming, in combination, means for dimensioning the transit time of said measuring chirp signal outside said subject, the transit time of said reference chirp signal, and said upper limit frequency of said filter means for causing said filtered signal to represent substantially only parts of said emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length.
-
-
41. An apparatus for optically analyzing tissue in vivo comprising:
-
a coherent light source generating a coherent optical chirp signal of light selected from the group consisting of visible, NIR and IR light; signal generator means for generating an electrical reference chirp signal supplied to said coherent light source for modulating said optical chirp signal so that said optical chirp signal has a defined phase relationship to said reference chirp signal; a light exit zone, optically coupled to said coherent light source, from which the modulated optical chirp signal is directed, as a measuring chirp signal, at a tissue-containing subject, a part of said measuring chirp signal emerging from said subject after interacting with tissue therein to be analyzed and forming an optical emerging signal; detector means, having a light entry zone into which said optical emerging signal enters, for converting said optical emerging signal into a corresponding electrical emerging signal; mixer means for electronically mixing said electrical emerging signal with said reference chirp signal to form an electrical superposition signal having sets of beats, each set of beats having a respective beat frequency; filter means, for receiving said electrical superposition signal and having a transmission range with an upper limit frequency, for generating from said superposition signal a filtered signal consisting of an electrical superposition signal having at least one beat frequency within said transmission range; means for adjusting at least one of a distance between said signal generator means and said coherent light source, a distance between said signal generator means and said mixer means, a distance between said coherent light source and said light exit zone, a distance between said light entry zone and said mixer means, and said upper limit frequency for, in combination, dimensioning the transit time of said measuring chirp signal outside said subject, the transit time of said reference chirp signal and said upper limit frequency of said filter means for causing said filtered signal to represent substantially only parts of said optical emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length. - View Dependent Claims (42, 43, 44, 45)
-
-
46. An apparatus for optically analyzing tissue in vivo comprising:
-
a coherent light source generating a coherent optical chirp signal of light selected from the group consisting of visible, NIR and IR light; signal generator means for generating an electrical reference chirp signal supplied to said coherent light source for modulating said coherent optical chirp signal; a single light exit zone, optically coupled to said coherent light source, from which the modulated optical chirp signal, as a measuring chirp signal, exits toward a tissue-containing subject, a part of said measuring chirp signal emerging from said subject after interacting with tissue therein to be analyzed and forming an optical emerging signal; a plurality of detector elements arranged around said subject at respective positions which are stationary relative to said subject; means for generating relative motion between said light exit zone and said subject so that a part of said optical emerging signal is successively incident on said detector elements for scanning said subject, each detector element generating an electrical signal corresponding to the part of the optical emerging signal incident thereon; a plurality of mixers corresponding in number to the plurality of detector elements, all of said mixers receiving said electrical reference chirp signal and said mixers respectively receiving said electrical signals from said detector elements, and each mixer superimposing the electrical signal from the detector element connected thereto with said electrical reference chirp signal to form a superposition signal having sets of beats, each set of beats having a respective beat frequency; a plurality of filters corresponding in number to the plurality of mixers, said filters respectively receiving said superposition signals from said mixers, each filter having an identical upper limit frequency and generating from a superposition signal supplied thereto from a mixer a filtered signal having at least one beat frequency within said transmission range; means for combining said filtered signals to form a combined filtered signal; and means for adjusting at least one of a distance between said signal generator means and said mixers, a distance between said coherent light source and said light exit zone and said upper limit frequency for, in combination, dimensioning the transit time of said measuring chirp signal outside said subject, the transit time of said electrical reference chirp signal, and said upper limit frequency of said filters for causing said combined filtered signal to represent substantially only parts of said optical emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length.
-
-
47. An apparatus for optically analyzing tissue in vivo comprising:
-
a coherent light source generating a coherent optical chirp signal of light selected from the group consisting of visible, NIR and IR light; signal generator means for generating an electrical reference chirp signal supplied to said coherent light source for modulating said coherent optical chirp signal; a plurality of light exit zones arranged around said subject at respective positions which are stationary relative to said subject, and means for successively, optically coupling said light exit zones one at a time to said coherent light source, from which the modulated optical chirp signal, as a measuring chirp signal, exits toward a tissue-containing subject, a part of said measuring chirp signal emerging from said subject after interacting with tissue therein to be analyzed and forming an optical emerging signal; a plurality of detector elements arranged around said subject at respective positions which are stationary relative to said subject in alternation with said light exit zones, each detector element disposed to receive light from only one light exit zone; each detector element generating an electrical signal corresponding to the part of the optical emerging signal incident thereon as said light zones are successively coupled to said coherent light source for scanning said subject; a plurality of mixers corresponding in number to the plurality of detector elements, all of said mixers receiving said electrical reference chirp signal and said mixers respectively receiving said electrical signals from said detector elements, and each mixer superimposing the electrical signal from the detector element connected thereto with said electrical reference chirp signal to form a superposition signal having sets of beats, each set of beats having a respective beat frequency; a plurality of filters corresponding in number to the plurality of mixers, said filters respectively receiving said superposition signals from said mixers, each filter having an identical upper limit frequency and generating from a electrical superposition signal received from a mixer a filtered signal having at least one beat frequency within said transmission range; means for combining said filtered signals to form a combined filtered signal; and means for adjusting at least one of a distance between said signal generator means and said mixers, a distance between said coherent light source and said light exit zone and said upper limit frequency for, in combination, dimensioning the transit time of said measuring chirp signal outside said subject, the transit time of said electrical reference chirp signal, and said upper limit frequency of said filters for causing said combined filtered signal to represent substantially only parts of said optical emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length.
-
-
48. An apparatus for optically analyzing tissue in vivo comprising:
-
a plurality of coherent light sources each generating a coherent optical chirp signal of light selected from the group consisting of visible, NIR and IR light, said coherent light sources being arranged around a tissue-containing subject at respective positions which are stationary relative to said subject; signal generator means for generating an electrical reference chirp signal supplied to said coherent light source for modulating said coherent optical chirp signal; means for successively energizing said coherent light sources, one at a time for directing the modulated optical chirp signal, as a measuring chirp signal, at said containing subject for scanning said subject, a part of said measuring chirp signal emerging from said subject after interacting with tissue therein to be analyzed and forming an optical emerging signal; a plurality of detector elements arranged around said subject at respective positions which are stationary relative to said subject, in alternation with said coherent light sources, each detector element disposed to receive light from only one of said coherent light sources so that a part of said optical emerging signal is successively incident on said detector elements as said coherent light sources are successively energized, each detector element generating an electrical signal corresponding to the part of the optical emerging signal incident thereon; a plurality of mixers corresponding in number to the plurality of detector elements, all of said mixers receiving said electrical reference chirp signal and said mixers respectively receiving said electrical signals from said detector elements, and each mixer superimposing the electrical signal from the detector element connected thereto with said electrical reference chirp signal to form a superposition signal having sets of beats, each set of beats having a respective beat frequency; a plurality of filters corresponding in number to the plurality of mixers, said filters respectively receiving said superposition signals from said mixers, each filter having an identical upper limit frequency and generating from an electrical superposition signal received from a mixer a filtered signal having at least one beat frequency within said transmission range; means for combining said filtered signals to form a combined filtered signal; and means for adjusting at least one of a distance between said signal generator means and said mixers, a distance between said coherent light source and said light exit zone and said upper limit frequency for, in combination, dimensioning the transit time of said measuring chirp signal outside said subject, the transit time of said electrical reference chirp signal, and said upper limit frequency of said filters for causing said combined filtered signal to represent substantially only parts of said optical emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length.
-
-
49. A method for optically analyzing tissue in vivo comprising the steps of:
-
directing a measuring chirp signal at a tissue-containing subject, said measuring chirp signal being a coherent optical signal of light selected from the group consisting of visible, NIR and IR light, a part of said measuring chirp signal emerging from said subject after interacting therein with tissue to be analyzed and forming an emerging signal; generating a reference chirp signal having a defined phase relationship to said measuring chirp signal; superimposing said emerging signal with said reference chirp signal to form a superposition signal having sets of beats, each set of beats having a respective beat frequency; filtering said superposition signal through a transmission range with an upper limit frequency, for generating from said superposition signal a filtered signal having at least one beat frequency within said transmission range; and dimensioning parameters including the transit time of said measuring chirp signal outside said subject, the transit time of said reference chirp signal, and said upper limit frequency of said filter means for causing said filtered signal to represent substantially only parts of said emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length. - View Dependent Claims (50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66)
-
-
67. A method for optically analyzing tissue in vivo comprising the steps of:
-
generating a coherent optical chirp signal of light selected from the group consisting of visible, NIR and IR light; splitting said optical chirp signal, at a splitting location, into a measuring chirp signal and a reference chirp signal having a defined phase relationship to said measuring chirp signal; selecting one fiber from a first group of optical fibers, having respectively different combinations of refractive index and length, to conduct said measuring chirp signal from said splitting location to a tissue-containing subject, a part of said measuring chirp signal emerging from said subject after interacting with tissue therein to be analyzed and forming an emerging signal; superimposing said emerging signal, at a superimposing location, with said reference chirp signal to form an optical superposition signal having sets of beats, each set of beats having a respective beat frequency; selecting one fiber from a second group of separate optical fibers, having respectively different combinations of refractive index and length, for conducting said reference chirp signal from said splitting location to said superimposing location; selecting one fiber from a third group of separate optical fibers, having respectively different combinations of refractive index and length, for conducting said emerging signal from said subject to said superimposing location; converting said optical superposition signal into an electrical superposition signal; filtering said electrical superposition signal through a transmission range with an upper limit frequency, for generating from said electrical superposition signal a filtered signal having at least one beat frequency within said transmission range; and selecting said upper limit frequency, in combination with the transit time of said measuring chirp signal outside said subject defined by selecting respective ones of said optical fibers in said first and third groups and the transit time of said reference chirp signal defined by selecting one of said optical fibers in said second group, for causing said filtered signal to represent substantially only parts of said emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length. - View Dependent Claims (68, 69, 70, 71)
-
-
72. A method for optically analyzing tissue in vivo comprising the steps of:
-
generating a coherent optical chirp signal of light selected from the group consisting of visible, NIR and IR light, said optical chirp signal propagating along a first propagation path; directing said optical chirp signal at a semi-reflective mirror disposed in said first propagation path at an angle deviating from 90°
for splitting said optical chirp signal into a measuring chirp signal which continues to propagate along said first propagation path toward a tissue-containing subject, and a reference chirp signal propagating along a second propagation path, different from said first propagation path, a part of said measuring chirp signal emerging from said subject after interacting with tissue therein to be analyzed and forming an emerging signal propagating back along said first propagation path toward said semi-reflective mirror;disposing a fully-reflective mirror a distance from said semi-reflective mirror in said second propagation path for directly and fully reflecting said reference chirp signal back along said second propagation path toward said semi-reflective mirror so that said reference chirp signal has a defined phase relationship to said measuring chirp signal; passing said fully reflected reference chirp signal through said semi-reflective mirror and deflecting said emerging signal by said semi-reflective mirror for superimposing both signals to form an optical superposition signal having sets of beats, each set of beats having a respective beat frequency; converting said optical superposition signal, at a converting location into a corresponding electrical superposition signal; filtering said electrical superposition signal through a transmission range with an upper limit frequency, for generating from said electrical superposition signal a filtered signal having at least one beat frequency within said transmission range; adjusting the distance between said semi-reflective mirror and said fully reflective mirror; adjusting the distance between said semi-reflective mirror and said examination subject; adjusting the distance between said semi-reflective mirror and said converting location; selecting said upper limit frequency; and selectively adjusting said distances and said upper limit frequency, in combination, for dimensioning the transit time of said measuring chirp signal outside said subject, the transit time of said reference chirp signal, and said upper limit frequency for causing said filtered signal to represent substantially only parts of said emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length.
-
-
73. A method for optically analyzing tissue in vivo comprising the steps of:
-
generating a coherent optical chirp signal from a coherent light source emitting light selected from the group consisting of visible, NIR and IR light; generating, from a generator source, an electrical reference chirp signal supplied to said coherent light source for modulating said optical chirp signal so that said optical chirp signal has a defined phase relationship to said reference chirp signal; optically coupling a light exit zone, to said coherent light source, from which the modulated optical chirp signal is directed, as a measuring chirp signal, at a tissue-containing subject, a part of said measuring chirp signal emerging from said subject after interacting with tissue therein to be analyzed and forming an optical emerging signal; receiving said optical emerging signal via a light entry zone and converting said optical emerging signal into a corresponding electrical emerging signal; electronically mixing said electrical emerging signal, at a mixing location, with said reference chirp signal to form an electrical superposition signal having sets of beats, each set of beats having a respective beat frequency; filtering said electrical superposition signal through a transmission range with an upper limit frequency, for generating from said electrical superposition signal a filtered signal having at least one beat frequency within said transmission range; adjusting at least one of a distance between said generator source means and said coherent light source, a distance between said signal generator source and said mixing location, a distance between said coherent light source and said light exit zone, a distance between said light entry zone and said mixing location, and said upper limit frequency for, in combination, dimensioning the transit time of said measuring chirp signal outside said subject, the transit time of said reference chirp signal and said upper limit frequency of said filter means for causing said filtered signal to represent substantially only parts of said optical emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length. - View Dependent Claims (74, 75, 76, 77)
-
-
78. A method for optically analyzing tissue in vivo comprising the steps of:
-
generating a coherent optical chirp signal from a coherent light source emitting light selected from the group consisting of visible, NIR and IR light; generating, from a generator source, an electrical reference chirp signal supplied to said coherent light source for modulating said coherent optical chirp signal; optically coupling a single light exit zone, to said coherent light source, from which the modulated optical chirp signal, as a measuring chirp signal, is directed at a tissue-containing subject, a part of said measuring chirp signal emerging from said subject after interacting with tissue therein to be analyzed and forming an optical emerging signal; arranging a plurality of detector elements around said subject at respective positions which are stationary relative to said subject; generating relative motion between said light exit zone and said subject so that a part of said optical emerging signal is successively incident on said detector elements for scanning said subject, each detector element generating an electrical signal corresponding to the part of the optical emerging signal incident thereon; superimposing each of the respective electrical signals from the detector elements at a mixing location with said electrical reference chirp signal to form a plurality of superposition signals each having sets of beats, each set of beats having a respective beat frequency; separately fitting each of said superposition signals through transmission ranges identical upper limit frequency and thereby generating from said electrical superposition signals a plurality of respective filtered signals each having at least one beat frequency within said transmission range; combining said filtered signals to form a combined filtered signal; and adjusting at least one of a distance between said generator source and said mixing location, a distance between said coherent light source and said light exit zone and said upper limit frequency for, in combination, dimensioning the transit time of said measuring chirp signal outside said subject, the transit time of said electrical reference chirp signal, and said upper limit frequency for causing said combined filtered signal to represent substantially only parts of said optical emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length.
-
-
79. A method for optically analyzing tissue in vivo comprising the steps of:
-
generating a coherent optical chirp signal from a coherent light source emitting light selected from the group consisting of visible, NIR and IR light; generating, from a generator source an electrical reference chirp signal supplied to said coherent light source for modulating said coherent optical chirp signal; arranging a plurality of light exit zones around said subject at respective positions which are stationary relative to said subject, and for successively, optically coupling said light exit zones one at a time to said coherent light source, from which the modulated optical chirp signal, as a measuring chirp signal, exits toward a tissue-containing subject, a part of said measuring chirp signal emerging from said subject after interacting with tissue therein to be analyzed and forming an optical emerging signal; arranging a plurality of detector elements arranged around said subject at respective positions which are stationary relative to said subject in alternation with said light exit zones, each detector element disposed to receive light from only one light exit zone; generating from each detector element an electrical signal corresponding to the part of the optical emerging signal incident thereon as said light zones are successively coupled to said coherent light source for scanning said subject for scanning said subject; superimposing each electrical signal from each detector element at a mixing location with said electrical reference chirp signal to form a plurality of superposition signals having sets of beats, each set of beats having a respective beat frequency; separately filtering said superposition signals through transmission ranges having an identical upper limit frequency and thereby generating from said electrical superposition signals supplied thereto from a mixer a plurality of respective filtered signals each having at lease one beat frequency within said transmission range; combining said filtered signals to form a combined filtered signal; and adjusting at least one of a distance between said generator source and said mixing location, a distance between said coherent light source and said light exit zone and said upper limit frequency for, in combination, dimensioning the transit time of said measuring chirp signal outside said subject, the transit time of said electrical reference chirp signal, and said upper limit frequency for causing said combined filtered signal to represent substantially only parts of said optical emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length.
-
-
80. A method for optically analyzing tissue in vivo comprising the steps of:
-
generating a plurality of coherent optical chirp signals from a plurality of coherent light sources each emitting light selected from the group consisting of visible, NIR and IR light; arranging said coherent light sources being arranged around a tissue-containing subject at respective positions which are stationary relative to said subject; generating, from a generator source, an electrical reference chirp signal supplied to said coherent light source for modulating said coherent optical chirp signal; successively energizing said coherent light sources, one at a time for directing the modulated optical chirp signal, as a measuring chirp signal, at said containing subject for scanning said subject, a part of said measuring chirp signal emerging from said subject after interacting with tissue therein to be analyzed and forming an optical emerging signal; arranging a plurality of detector elements around said subject at respective positions which are stationary relative to said subject, in alternation with said coherent light sources, each detector element disposed to receive light from only one of said coherent light sources so that a part of said optical emerging signal is successively incident on said detector elements as said coherent light sources are successively energized, and generating from each detector element an electrical signal corresponding to the part of the optical emerging signal incident thereon; superimposing each electrical signal from each detector element at a mixing location with said electrical reference chirp signal to form a plurality of superposition signals each having sets of beats, each set of beats having a respective beat frequency; separately filtering said superposition signals through transmission ranges having an identical upper limit frequency and thereby generating from said superposition signals a plurality of respective filtered signals each having at least one beat frequency within said transmission range; combining said filtered signals to form a combined filtered signal; and adjusting at least one of a distance between said generator source and said mixing location, a distance between said coherent light source and said light exit zone and said upper limit frequency for, in combination, dimensioning the transit time of said measuring chirp signal outside said subject, the transit time of said electrical reference chirp signal, and said upper limit frequency for causing said combined filtered signal to represent substantially only parts of said optical emerging signal which have traversed an optical path length in said subject which does not exceed a defined maximum optical path length.
-
Specification