Method for taking a spatially resolved spectrum by means of a fourier-transform (FT)-spectrometer and such spectrometer
A method for taking a spatially resolved spectrum, in particular an infrared (IR) spectrum, of a sample by means of a Fourier-transform (FT)-spectrometer, is described wherein light emitted by a light source is fed to an interferometer, directed onto the sample and detected by an array-detector, wherein a movable reflector of the interferometer is displaced over a distance s and the array-detector is read out at a number n of predetermined discrete way points s 1 , . . . , s n of the distance s, respectively. When the movable reflector is displaced over the distance s, the array-detector is first read out at respective non-adjacent way points s d separated by at least one respective intermediate way point s i , and that the movable reflector is displaced over the distance s at least twice, wherein the array-detector is read out at the way points s i upon a second or further repeated displacement over the distance s.
1. A method for taking a spatially resolved spectrum of a sample by means of a Fourier-transform (FT)-spectrometer, comprising the steps of:
feeding light emitted by a light source to an interferometer, said interferometer comprising a movable reflector, and displacing said movable reflector along a distance s;
directing said light coming from said interferometer onto said sample;
detecting said light coming from said sample by an array-detector; and
reading out said array-detector at a number n of predetermined discrete way points s 1 , . . . , s n of said distance s, respectively, wherein said array-detector is first read out at respective non-adjacent way points s d of said discrete way points s 1 , . . . , s n which are separated by at least one respective intermediate way point s i , and wherein said movable reflector is displaced over said distance s at least twice, wherein said array-detector is read out at said intermediate way points s i during a second or further repeated displacement of said reflector along said distance s.
2. The method of claim 1 , wherein said array-detector is read out at way points s 1 , s 1+m , s 1+2m , . . . s n−m+1 during a first displacement of said reflector along said distance s, at way points s 2 , s 2+m , s 2+2m , . . . , s n−m+2 during at least a second displacement of said reflector along said distance s, and at way points s m , s 2m , . . . , s n during a m th displacement of said reflector along said distances, wherein 1<m<n and n:m is an integer.
3. The method of claim 2 , wherein m is chosen in dependence on a data rate of said array-detector.
4. The method of claim 1 , wherein said array-detector is read out in two directions of displacement of said movable reflector.
5. The method of claim 1 , wherein said array-detector is read out in one of two directions of displacement of said movable reflector only, wherein said reflector is returned in an initial position after each displacement along said distance s.
6. The method of claim 5 , wherein said reflector is returned at a rate which is higher than the rate when displaced for reading out said array-detector.
7. The method of claim 1 , wherein said reflector is continuously displaced at a constant rate when displaced for reading out said array-detector.
8. The method of claim 1 , wherein said reflector is displaced at a rate in the range of about 4 to 6 cm/s.
9. A Fourier-Transform (FT)-spectrometer for taking a spatially resolved spectrum of a sample, comprising:
a light source;
an interferometer having a movable reflector which is displaceable along a distance s;
an array-detector; and
a control operatively connected with said array-detector in order to read out said array-detector at a number n of predetermined discrete way points s 1 , . . . , s n of said distance s, respectively, said control being configured such that, when said movable reflector is displaced along said distance s, said array-detector is first read out at respective non-adjacent way points s d separated by at least one respective intermediate way point s i , and said movable reflector is displaced along said distance s at least twice, wherein said array-detector is read out at said way points s i during a second or further repeated displacement along said distance s.