Diamond machining of diffraction gratings for imaging spectrometers

► Imaging spectrometers require axisymmetric optics with integrated diffraction gratings. ► We explore the manufacture of gratings with 5-axis ultra-precision machine tools. ► Results show that multi-axis diamond machining may replace more expensive techniques. High quality imaging spectroscopy data is useful for both military and civilian applications. State-of-the-art spectrometers incorporate spherically concentric, axially symmetric and telecentric optical design. However, these designs require a diffraction grating operating in reflection that is manufactured on a convex, spherical or possibly freeform surfaces, and thus traditional grating manufacturing methods limit modern designs and raise costs. Further, it is often desirable to manufacture such optics in a monolithic configuration aligning them and eliminating assembly. This paper explores the capability of new 5-axis ultra-precision machine tools for manufacturing diffraction gratings in simplified experiments aimed at progressing toward producing gratings on freeform surfaces and monolithic combined optical designs.