Design and fabrication of infrared hybrid refractive/diffractive optical system for 3-5μm band

An infrared hybrid refractive/diffractive optical system for 3-5mum band, which is composed of four refractive elements and one binary optical element(BOE), has been designed and manufactured. The BOE, whose chromatic behavior is opposite to that of the refractive element, has made it possible for us to design the diffraction-limited optical system with field of 4(0) x 4(0), aperture of 60mm, F-number of 2.46, total track of 140mm and temperature range from -30degreesC similar to 70degreesC. A polar coordinate laser direct writing system (PLDWS) and a reactive ion beam etching (RIBE) device have been established to manufacture the BOE. The imaging performance of our optical system has been tested by Ealing IR MTF equipment, which shows that the diameter of spot is less than 80mum when the energy within the spot is 90% of the total.