High-sensitivity moiré interferometry—A simplified approach

High-quality moire-interferometry patterns were obtained with the following conditions: specimen of graphite-polyimide composite material; reflective cross-line specimen grating of 600 ℓ/mm (15,000 ℓ/in.); virtual reference grating of 1200 ℓ/mm (30,000 ℓ/in); fringe-multiplication factor of 2; carrier pattern of 10 fringes/mm (250/in.); carrier eliminated by optical filtering. The phase-type specimen grating was cast onto the composite material with silicone rubber, using a ‘homemade’ mold. The virtual grating was formed with a plane mirror in a collimated field. Precision-quality optical elements are not required.