IR microscope
An IR microscope includes an IR light source/interferometer ( 1 ) generating a collimated IR beam ( 26 ), an effectively beam-limiting element ( 8 ) in a stop plane ( 27 ), a sample position ( 15 ), a detector ( 19 ) having an IR sensor ( 19 a), a detector stop ( 19 b), a first optical device focusing the collimated IR beam onto the sample position, and a second optical device imaging the sample position onto the IR sensor. The effectively beam-limiting element is situated in the collimated IR beam. The first and second optical devices image the detector stop opening into an input beam plane. For the area A1 of the image of the detector stop opening in the input beam plane and the area A2 of the cross section of the collimated IR beam in the input beam plane: 0<A1/A2≤1. Thereby, only collimated IR radiation is picked up, while vignetting and stray radiation are avoided.
1. An infrared (IR) microscope comprising
an IR light source configured to generate a collimated IR input beam,
an effectively beam-limiting element in a stop plane in the collimated IR input beam,
a sample position for supporting a sample,
an IR detector having an IR sensor,
a detector stop having a detector stop opening, wherein the detector stop is arranged upstream of the IR sensor,
a first optical device configured to focus the collimated IR input beam generated by the IR light source onto the sample position, and
a second optical device configured to image the sample position onto the IR sensor, wherein the second optical device comprises an objective and an intermediate optical unit,
wherein the effectively beam-limiting element is situated in the collimated IR input beam upstream of the first optical device, and the first optical device and the second optical device are situated to image the detector stop opening of the detector stop into an input beam plane, and wherein, for an area A1 of an image of the detector stop opening in the input beam plane and an area A2 of a cross section of the collimated IR input beam in the input beam plane:
0< A 1/ A 2≤1.
2. The IR microscope as claimed in claim 1 , further comprising a further objective, configured to focus the collimated IR input beam onto the sample position.
3. The IR microscope as claimed in claim 1 , wherein the objective is also comprised by the first optical device and is configured to focus the collimated IR input beam onto the sample position, and wherein the IR microscope further comprises a beam splitter optical unit configured to couple the collimated IR input beam generated by the IR light source into the objective.
4. The IR microscope as claimed in claim 1 , wherein the detector stop and the IR sensor are situated within a common detector housing and are arranged at a distance d away from one another.
5. The IR microscope as claimed in claim 4 , wherein the distance d is a maximum of 50 mm.
6. The IR microscope as claimed in claim 1 , wherein the intermediate optical unit has an effective focal length f for which:
f
=
d
⋆
x
x
⋆
m
-
d
/
m
where
f: effective focal length of the intermediate optical unit
x: distance between the image of the detector stop opening in the input beam plane that is created by the first optical device and by the objective of the second optical device and an image of the sample that is created by the objective of the second optical device
d: distance between the detector stop and the IR sensor
m: magnification factor of the intermediate optical unit.
7. The IR microscope as claimed in claim 6 , wherein the magnification factor m of the intermediate optical unit is m=1.
8. The IR microscope as claimed in claim 1 , wherein the effectively beam-limiting element is an output aperture of the IR light source.
9. The IR microscope as claimed in claim 1 , wherein the effectively beam-limiting element and the input beam plane are arranged within the IR light source.
10. The IR microscope as claimed in claim 1 , wherein the input beam plane is the stop plane.
11. The IR microscope as claimed in claim 1 , wherein the intermediate optical unit comprises an Offner objective.
12. The IR microscope as claimed in claim 1 , wherein the IR light source comprises an interferometer, a quantum cascade laser or a Fourier-transform infra-red (FTIR) spectrometer.