Spectrally adjustable filter

A method for spectrally filtering at least one input beam, comprising:

• dispersing spectral components of the at least one input beam at different respective angles in a spectral plane;
• changing at least some angles of propagation axes of the dispersed spectral components so that a maximum angular separation among the propagation axes of the dispersed spectral components changes by passing the dispersed spectral components through at least a first optical element having first and second non-parallel surfaces through which the dispersed spectral components pass, with the first optical element substantially preserving collimation of the dispersed spectral components over an entire propagation path between the first and second non-parallel surfaces;
• receiving a plurality of the dispersed spectral components incident on a single reflective surface in which central rays of the dispersed spectral components are incident at different points on the single reflective surface;
• and
• tilting the single reflective surface to select at least one and fewer than all of the received spectral components to be directed to a selected output path.

A system for monitoring spectra of spectral components of at least one input beam, comprising:

• a spectrally dispersive element configured to disperse spectral components of the at least one input beam at different respective angles in a spectral plane;
• one or more optical elements, including at least a first optical element having first and second non-parallel surfaces through which the dispersed spectral components pass, configured to change at least some angles of propagation axes of the dispersed spectral components so that the maximum angular separation among the propagation axes of the spectral components changes, with the first optical element configured to substantially preserve collimation of the dispersed spectral components over an entire propagation path between the first and second non-parallel surfaces;
• a single reflective surface configured to receive a plurality of the dispersed spectral components in which central rays of the dispersed spectral components are incident at different points on the single reflective surface, and to tilt to select at least one and fewer than all of the received spectral components to be directed to a selected output path;
• and
• at least one detector configured to receive a spectral component directed to a selected output path.

An apparatus for spectrally filtering at least one input beam, comprising:

• a spectrally dispersive element configured to disperse spectral components of the at least one input beam at different respective angles in a spectral plane;
• one or more optical elements configured to change at least some angles of propagation axes of the dispersed spectral components, at least one optical element being located at a distance from the spectrally dispersive element that is less than a focal length of the at least one optical element;
• and
• a single reflective surface configured to receive a plurality of the dispersed spectral components, and to tilt to select at least one and fewer than all of the received spectral components to be directed to a selected output path.

An apparatus for spectrally filtering at least one input beam, comprising:

• a spectrally dispersive element configured to disperse spectral components of the at least one input beam at different respective angles in a spectral plane;
• one or more optical elements, including at least a first optical element having first and second non-parallel surfaces through which the dispersed spectral components pass, configured to change at least some angles of propagation axes of the dispersed spectral components so that a maximum angular separation among the propagation axes of the spectral components increases, and to change a transverse spatial extent of each of the spectral components to be smaller than a transverse spatial extent of the at least one input beam incident on the spectrally dispersive element, with the first optical element configured to substantially preserve collimation of the dispersed spectral components over an entire propagation path between the first and second non-parallel surfaces;
• and
• a single reflective surface configured to receive a plurality of the dispersed spectral components, and to tilt to select at least one and fewer than all of the received spectral components to be directed to a selected output path.