Digital micromirror transient response influence on superfast 3D shape measurement

• Novel discovery on the fundamental limitations of the digital micromirror device (DMD) on high-speed 3D shape measurement.
• Novel methodology to effectively reduce the measurement error caused by the transient response of the DMD chip.
• Exhaustive experiments on investigating the issues associated with DMD transient response.

Nowadays, the high speed (e.g., kilo-Hertz) refreshing rate of the digital micro-mirror device (DMD) has enabled superfast 3D shape measurement using the binary defocusing technique. This research finds that when the system reaches its extreme binary pattern refreshing rate, the transient response of the DMD induces a coupling effect (i.e., two neighboring patterns blend together) that may cause substantial measurement error. Since this transient response repeats itself, this systematic measurement error is substantially reduced to a negligible level when the timing between the projector and the camera is properly adjusted. Experimental results are presented to demonstrate the observed phenomena, and the success of utilizing the proposed method to overcome the problems associated with the transient response of the DMD.