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.