Chromatic aberration correction in a multiwavelength light beam deflection system

A light deflection system including chromatic correction comprising:

• an alterable diffraction grating
• a source of a multiwavelength input light beam that is directed along an input optical axis that intersects said grating;
• said grating generating a plurality of first order light beams from said input light beam, each different wavelength of said input light beam being deflected a correspondingly different angle from said optical axis;
• first and second lenses oriented with their optical axes coaxial with said input optical axis, said first lens a focal length from said grating, said first and second lenses spaced apart a distance equal to the sum of their focal lengths;
• first and second correction plates oriented with their optical axes coaxial with said input optical axis and intermediate said first and second lenses, said first plate positive, said second plate negative and spaced a distance apart such that the principle rays of light of various wavelengths substantially coincide at a point on the second compensation plate, said second compensation plate of sufficient strength to substantially co-axialize said principle rays of various wavelengths.