PHASE DIFFERENCE AMPLIFIER AND PHASE DIFFERENCE AMPLIFICATION METHOD USING DIGITAL HOLOGRAPHY

摘要

PROBLEM TO BE SOLVED: To perform large-magnification phase difference amplification by a simple optical system without amplifying noises such as air fluctuation, external vibration, or speckles, if any.;SOLUTION: A phase object 5 is recorded by using a holography technique. When regenerating it, not only ±1st-order diffracted light is generated as regenerated light of the object but also higher-order refracted light of higher harmonic is generated having a phase of an integral multiple owing to nonlinearity of a recording material. Here, with respect to nth-order diffracted light, the phase difference of the recorded object is amplified by n times. This phase difference amplification method utilizes this phenomenon and two phase-difference-amplified beams of higher-order refracted light are caused to interfere with each other for measurement. For example, when nth and -nth order diffracted light are caused to interfere with each other, the phase difference of the object is amplified by 2n times, making it possible to measure a phase on even an object having a small phase change and to obtain a contour line for each λ/(2n). According to this amplification method using digital holography, a hologram is taken into a computer to regenerate the hologram in the computer for phase difference amplification.;COPYRIGHT: (C)2006,JPO&NCIPI