Tunable spectral slicer and methods of use
Systems and methods for filtering an optical beam are described. In one implementation, a system for filtering an input optical beam includes a first beamsplitter, a first spectral slicing module, a second spectral slicing module, and a second beamsplitter. The first beamsplitter is configured to split the input optical beam into a first optical beam and a second optical beam. The first spectral slicing module has a first passband and is configured to filter the first optical beam. The second spectral slicing module has a second passband and is configured to filter the second optical beam. The second beamsplitter is configured to combine the first optical beam and the second optical beam into an output optical beam. The first and second spectral slicing modules may each comprise a longpass filter and a shortpass filter aligned along its optical axis, and the longpass filter and/or the shortpass filter are rotatable relative to the optical axis. Advantageously, the optical system allows for tunable spectral filtering of the input optical beam suitable for 2-D imaging systems.
1. An optical system for filtering an input optical beam, comprising:
a first beamsplitter configured to split the input optical beam into a first optical beam and a second optical beam;
a first spectral slicing module having a first passband and configured to filter the first optical beam, wherein the first spectral slicing module comprises a first longpass filter and a first shortpass filter aligned along a first optical axis, wherein at least one of the first longpass filter or the first shortpass filter is movable relative to the first optical axis;
a second spectral slicing module having a second passband and configured to filter the second optical beam, wherein the second spectral slicing module comprises a second longpass filter and a second shortpass filter aligned along a second optical axis, wherein at least one of the second longpass filter or the second shortpass filter is movable relative to the second optical axis, wherein the first and second passbands overlap in a first range of wavelengths; and
a second beamsplitter configured to combine the first optical beam and the second optical beam into an output optical beam.
2. The system of claim 1 , wherein the first passband has at least one of a bandwidth or a center wavelength that can be varied by moving the at least one of the first longpass filter or the first shortpass filter.
3. The system of claim 1 , wherein the at least one of the first longpass filter or the first shortpass filter is rotatable relative to the first optical axis.
4. The system of claim 1 , wherein the first spectral slicing module further comprises a blocking filter that blocks wavelengths of the first optical beam outside the first passband.
5. The system of claim 1 , wherein the first beamsplitter is a dichroic beamsplitter and has a transition region that spans a second range of wavelengths, and wherein the second range of wavelengths includes at least a portion of the first range of wavelengths.
6. The system of claim 5 , wherein the second range of wavelengths is narrower than the first range of wavelengths.
7. The system of claim 1 , wherein the second beamsplitter is a dichroic beamsplitter.
8. The system of claim 1 , further comprising one or more mirrors configured to direct the propagation of the first and/or second optical beams.
9. The system of claim 1 , wherein the first spectral slicing module further comprises an optical spatial compensator that increases an optical path length traveled by the first optical beam between the first beamsplitter and the second beamsplitter.
10. The system of claim 1 , wherein the first spectral slicing module further comprises a compensation filter that corrects a lateral deviation of the first optical beam from the first optical axis of the first spectral slicing module.
11. The system of claim 1 , wherein the first and second optical beams propagate along the same direction after being combined into the output optical beam.
12. The system of claim 1 , wherein the input optical beam and the output optical beam remain substantially collinear.
13. A method for filtering an input optical beam, comprising:
splitting the input optical beam into a first optical beam and a second optical beam using a first beamsplitter;
filtering the first optical beam by transmitting the first optical beam through a first spectral slicing module having a first passband, wherein the first spectral slicing module comprises a first longpass filter and a first shortpass filter aligned along a first optical axis, wherein at least one of the first longpass filter or the first shortpass filter is movable relative to the first optical axis;
filtering the second optical beam by transmitting the second optical beam through a second spectral slicing module having a second passband, wherein the second spectral slicing module comprises a second longpass filter and a second shortpass filter aligned along a second optical axis, wherein at least one of the second longpass filter or the second shortpass filter is movable relative to the second optical axis, wherein the first and second passbands overlap in a first range of wavelengths; and
combining the first and second optical beams into an output optical beam using a second beamsplitter.
14. The method of claim 13 , further comprising tuning at least one of a bandwidth or a center wavelength of the first passband by moving the at least one of the first longpass filter or the first shortpass filter.
15. The method of claim 13 , further comprising blocking wavelengths of the first optical beam outside the first passband using a blocking filter.
16. The method of claim 13 , wherein the first beamsplitter is a dichroic beamsplitter and has a transition region that spans a second range of wavelengths, and wherein the second range of wavelengths includes at least a portion of the first range of wavelengths.
17. The method of claim 16 , wherein the second range of wavelengths is narrower than the first range of wavelengths.
18. The method of claim 13 , wherein the second beamsplitter is a dichroic beamsplitter.
19. The method of claim 13 , further comprising increasing an optical path length traveled by the first optical beam between the first beamsplitter and the second beamsplitter using at least one optical spatial compensator.
20. The method of claim 13 , further comprising correcting a lateral deviation of the first optical beam from the first optical axis of the first spectral slicing module using at least one compensation filter.