Frequency division multiplexing based rotating gratings projection for uniaxial microscopic measurement

A novel approach for uniaxial microscopic measurement, applying frequency division multiplexing based rotating gratings projection, is proposed. These rotating gratings consist of six angle-coded fringe patterns , and each records distinct depth information. With an optotune electronically focus-tunable lens, the projector continuously zooms and circularly projects six rotating gratings onto the surface of the measured object. Simultaneously, these light field distributions on the object surface will be collected by an image acquisition device and processed by a computer to be saved only as one picture. Consequently, this single image records light field information at multiple defocus levels, offering higher modulation extraction accuracy and requiring only one-third of the data storage compared to traditional Fourier transform modulation profilometry . • A micro-scale vertical measurement method uses a rotation grating with frequency division multiplexing . • Six angle-coded fringe patterns produce a 12-bit composite image, reducing storage and enhancing accuracy. • Subtraction and superimposition streamline data processing, improving reconstruction accuracy over traditional methods.