With a view to extending techniques for THz antenna near-field/far-field prediction, this communication derives general analytic expressions for calibrated phase shifting holography (PSH) and introduces a new 120º three-step PSH method that avoids switching off the reference field and has symmetrical performance over the entire complex plane, providing spurious free far-field prediction. Numerical tests with simulated near-field patterns at 372GHz confirm the convenience of the method and give an indication of the precision required for the phase shifts.
2. Leith, E. N. and J. Upatnieks, "Reconstructed wavefronts and communication theory," JOSA, Vol. 52, No. 10, 1123-1128, 1962.
3. Gabor, D., "Microscopy by reconstructed wavefronts," Proc. Roy. Soc., Vol. A, 454-487, 1949.
4. Gabor, D. and W. P. Goss, "Interference microscope with total wavefront reconstruction," JOSA, Vol. 56, No. 7, 849-856, 1966.
5. Yamaguchi, I. and T. Zhang, "Phase-shifting digital holography," Optics Letters, Vol. 22, No. 16, 1268-1270, 1997.
6. Meng, X. F., et al., "Two-step phase-shifting interferometry and its application in image encryption," Optics Letters, Vol. 31, No. 10, 1414-1416, 2006.
7. Liu, J. P. and T. C. Poon, "Two-step-only quadrature phase-shifting digital holography," Optics Letters, Vol. 34, No. 3, 250-252, 2009.
8. Junkin, G., "Planar near-field phase retrieval using GPUs for accurate THz far-field prediction," IEEE Transactions on Antennas and Propagation, Vol. 61, No. 4, 1763-1776, 2013.