Three-dimensional shape measurement with sinusoidal phase-modulating fiber-optic interferometer fringe

• A sinusoidal phase-modulating fiber-optic interferometer fringe projector with a feedback control system is reviewed.
• Sinusoidal phase shifting interferometry improved by introducing constant scaling factors to detect the desired phase is reported.
• The relationship between the modulation voltage and the phase modulation coefficient is discussed.
• The reflection signal that realizes measurement of the disturbance and feeds back to the modulated signal is reported.

A three-dimensional (3-D) shape measurement system using a fiber-optic interferometer fringe projector is presented and demonstrated. The system utilizes sinusoidal phase shifting interferometry to detect the desired phase which is improved by introducing constant scaling factors from linear phase shift interferometry algorithm, and the relationship between the modulation voltage and the phase modulation coefficient is analyzed; the system also utilizes the reflection signal to realize measurement of the disturbance and feed back to the modulated signal. Practical experiments validate the feasibility of this method. The phase accuracy is nearly 37.6 mrad and the measurement error is about 10 nm.