OPTICAL MEASUREMENT TECHNIQUES USING DAMMANN GRATINGS
Changhe Zhou
Abstract:
Optical measurement techniques using Dammann gratings and deep-etched gratings are reported. Dammann grating is a digital binary-phase diffractive optical element that can produce multiple equal intensitites in different diffractive orders. Three-dimensional objects can be measured using a Dammann grating when its surface deforms the lattice of the illumination array that is produced by a Dammann grating. A structure of three Dammann gratings can be used to characterize the ultrashort femtosecond laser pulse where one grating is used to split the ultrashort femtosecond laser pulse while the other two are used to collimate the split pulses and one of the two’s is moved along the optical axis relatively to give the controllable delay between the two split pulses. Experimental results demonstrated the effectiveness of Dammann SHG FROG (second- harmonic generation frequency-resolved optical gating) apparatus. It will also be reported that a phase-shifting measurement technique can be constructed by using three deep-etched fused silica gratings when one of the gratings is moved vertically to generate the required shifted phase between two split beams. Generally speaking, novel measurement techniques can be invented by using new diffractive optical elements.
