Method and apparatus for eye movement tracking in spectral optical coherence tomography (SD-OCT)
The invention relates to a method and an apparatus for collecting structural data with spectral optical coherence tomography from samples having a point of maximum reflectance. This point of maximum reflectance is used for adjusting the scanned path pattern.
1. Method for collecting structural data with spectral optical coherence tomography from samples ( 12 ) having a point of maximum reflectance comprising the steps of
a) performing a set of at least two B scans along at least two scanning lines ( 20 a , 20 b , 21 a , 21 b , 22 a , 22 b ) which scanning lines ( 20 a , 20 b , 21 a , 21 b , 22 a , 22 b ) are linearly independent and intersecting at a point of intersection;
b) identifying the maxima of light intensity along said scanning lines ( 20 a , 20 b , 21 a , 21 b , 22 a , 22 b );
c) determining the offset of said maxima from said point of intersection;
d) re-performing steps a) to c), whereby the position of at least one of said scanning lines ( 20 a , 20 b , 21 a , 21 b , 22 a , 22 b ) is changed and the point of intersection is adjusted in dependence of the result of the determination step c).
2. Method for collecting structural data according to claim 1 , characterized in that the re-performing step c) involves that the positions of at least two of the scanning lines ( 20 a , 20 b , 21 a , 21 b , 22 a , 22 b ) is changed.
3. Method for collecting structural data according to claim 2 , characterized in that the re-performing step c) further involves that the angle between both scanning lines ( 20 a , 20 b , 21 a , 21 b , 22 a , 22 b ) is unchanged.
4. Method for collecting structural data according to claim 3 , characterized in that the angle between both scanning lines ( 20 a , 20 b , 21 a , 21 b , 22 a , 22 b ) lies in a range between 70° and 120°.
5. Method for collecting structural data according to claim 4 , characterized in that the angle between both scanning lines ( 20 a , 20 b , 21 a , 21 b , 22 a , 22 b ) is 90°.
6. Method for collecting structural data according to claim 1 , characterized in that identifying the maxima of light intensity according to the identification step b) involves splitting the light returning from the sample ( 12 ) into a first portion used for spectral optical coherence tomography and a second portion used for detecting the light intensity.
7. Method for collecting structural data according to claim 3 , characterized in that the angle between both scanning lines ( 20 a , 20 b , 21 a , 21 b , 22 a , 22 b ) lies in a range between 80° and 110°.
8. Method for collecting structural data according to claim 1 , wherein the position of at least one of said scanning lines ( 20 a , 20 b , 21 a , 21 b , 22 a , 22 b ) is changed and the point of intersection is adjusted in dependence on the result of the determining in step c) by adjusting offsets in a scanning means ( 10 ), in the case of small offsets determined in step c), or by translating a holder ( 26 ) on which said scanning means ( 10 ) is mounted, in the case of larger offsets determined in step c).