Non-contact thermal measurements of VUV optics

A measurement system, comprising:

• an illumination source configured to generate an amount of primary illumination light;
• an illumination optics subsystem configured to project the primary illumination light onto a surface of a specimen, the illumination optics subsystem including:
• a first optical element disposed in an optical path of the amount of primary measurement light, wherein the amount of primary measurement light is incident on the first optical element over a first portion of the first optical element, wherein the first optical element is constructed of a material with low emissivity at long wavelength infrared wavelengths within a range of eight micrometers to fifteen micrometers;
• a first amount of material having high emissivity at the long wavelength infrared wavelengths disposed on the first optical element over a second portion of the first optical element that is separate from the first area of the first optical element;
• and
• an infrared camera system configured to perform IR-based temperature measurements of the first optical element with long wavelength infrared light having wavelengths in a range of eight micrometers to fifteen micrometers, wherein the second portion of the first optical element is in the field of view of the infrared camera system.

A method comprising:

• generating an amount of primary illumination light;
• projecting the primary illumination light onto a surface of a specimen, the primary illumination light having an optical path including one or more optical elements constructed from a material with low emissivity at long wavelength infrared wavelengths within a range of eight micrometers to fifteen micrometers;
• and
• imaging a temperature profile of the one or more optical elements with long wavelength infrared light having wavelengths in a range of eight micrometers to fifteen micrometers, wherein a portion of the one or more optical elements is coated with a material having high emissivity at the long wavelength infrared wavelengths, wherein the portion of the one or more optical elements coated with the high emissivity material is separate from a portion of the one or more optical elements in a direct optical path of the primary illumination light.