Ultraprecision micro-grinding of germanium immersion grating element for mid-infrared super dispersion spectrograph

The design of a mid-infrared high dispersion spectrograph with a resolution of 200,000 at 10 mum employing germanium immersion grating elements is req uired for the 'SUBARU' large space telescope. The authors applied an ultrap recision micro-grinding technique using fine-diamond grinding tools whose e dges have been sharpened by electrical and mechanical processes to fabricat e the element, and successfully obtained the required element with a sharp and smooth V-faced grating structure using germanium. The successful fabric ation of this element is expected to contribute to the production of a comp act and efficient high dispersion spectrograph in the development of the mo st advanced image analyzer.