Polychromator systems and methods

A polychromator system comprising:

• an optical element defining an aperture;
• a collimation mirror for receiving light via the aperture and reflecting substantially collimated light, wherein the reflective surface of the collimation mirror is described by:
• z
• ⁡
• (
• x
• ,
• y
• )
• =
• cr
• 2
• 1
• +
• 1
• -
• (
• 1
• +
• k
• )
• ⁢
• c
• 2
• ⁢
• r
• 2
• +
• ∑
• i
• =
• 1
• 35
• ⁢
• A
• i
• ×
• E
• i
• ⁡
• (
• x
• ,
• y
• )
• where
• ⁢
• ⁢
• r
• =
• x
• 2
• +
• y
• 2
• ,
• and where z is the height along an optical axis, x is the position along first axis and y is position along the second axis;
• at least a first dispersive optical component and a second dispersive optical component, each configured to disperse the substantially collimated light received from the collimation mirror by different amounts for different wavelengths and to provide cross-dispersed light having different wavelengths of light spaced along a first and second axis;
• and
• a focus mirror positioned to focus the cross-dispersed light onto a 2-D array detector to provide a plurality of aperture images of the aperture at a respective plurality of regions of the detector, each of the plurality of aperture images associated with a respective wavelength of the cross-dispersed light;
• wherein either one or both of the collimation mirror and the focus mirror is a freeform mirror having a reflective surface configured to mitigate effects of optical aberrations of the polychromator system over a plurality of the wavelengths of the cross-dispersed light along the first axis and the second axis and thereby optimize the resolution of the plurality of aperture images associated with the plurality of the wavelengths along the first axis and the second axis.