A tunable 3D optical diffraction tomography system with high measurement accuracy

We present a tunable experimental setup to obtain the three-dimensional refractive index distribution of microscopic biological structures. We introduce an adjustable system to change the position of the focal plane and perform stitched reconstruction. There are two main approaches for obtaining the projections of sample in optical diffraction tomography: beam scanning and rotating sample. Compared to beam scanning, the method of rotating sample allows the sample to be rotated 180° to capture uniformly distributed data, which improves the accuracy of the phase measurement and the resolution of the reconstruction result. The depth-of-field in the optical diffraction tomography setups is very small and the method of rotating sample inevitably causes the sample to deviate from the depth-of-field during the rotation, making it difficult to obtain ideal data. We divided the sample position deviation area into several ideal data acquisition areas and collected the ideal data in each area by shifting the position of the focal plane. By the combination of 180° projection method and stitched reconstruction method, we have obtained high measurement accuracy results with uniform resolution.