Multi-functional immersion grating by homemade freeform cutting machine

摘要

The application fields of Infrared spectroscopy are extremely wide from matter analysis of organisms to environmentalobservation. In wide-band spectroscopy, a pair of two different dispersive gratings is used. One is a high-order highdispersive grating according to the bandwidth of the detector; other is a low dispersive grating that separates theoverlapping order. In this work, a low dispersion grating was fabricated on the incident surface of a conventionalimmersion grating to manufacture the world's first multifunctional Germanium immersion grating having two gratings inone device. Positioning accuracy with respect to three-dimensional space with our homemade cutting machine has anextremely good accuracy of less than 3nm RMS locally and less than 15nm RMS globally. The grating surfaceroughness is less than 3nm RMS. We introduce next-generation diffractive grating processing technology with extremelyhigh freedom.