Tandem dispersive range monochromator

A method, comprising:

• rotating, by a grating drive motor, a diffraction grating to provide dispersed wavelengths of light by diffraction of light from a light source, the diffraction grating comprising a first periodic surface region and a second periodic surface region;
• detecting, by at least one detector, at least one of a portion of the dispersed wavelengths of light or a reflection thereof;
• and
• controlling, with processing circuitry, the grating drive motor to regulate a first angular velocity of the diffraction grating over a first range of motion for the first periodic surface region of the diffraction grating and to regulate a second angular velocity of the diffraction grating over a second range of motion for the second periodic surface region of the diffraction grating based on an angular orientation of the diffraction grating.

A monochromator, comprising:

• a light source that provides light;
• an entrance optics assembly that collimates the light;
• an entrance slit that passes at least a portion of the light;
• a diffraction grating comprising a first periodic surface region, a second periodic surface region, and a mounting assembly having a rotatable shaft to rotate the diffraction grating;
• a grating drive motor that rotates the diffraction grating about a pivot point of the rotatable shaft to provide dispersed wavelengths of light by diffraction of the portion of the light;
• an exit slit that passes at least a portion of the dispersed wavelengths of light;
• a detector configured to detect at least one of the portion of the dispersed wavelengths of light or a reflection thereof;
• and
• processing circuitry configured to control the grating drive motor to regulate a first angular velocity of the diffraction grating for the first periodic surface region and to regulate a second angular velocity of the diffraction grating for the second periodic surface region based on an angular orientation of diffraction grating.