For the implementation of a real‐time holographic camera, fast and automatic holographic image reconstruction is an essential technology. In this paper, we propose a new automatic depth‐detection algorithm for fast holography reconstruction, which is particularly useful for optical scanning holography. The proposed algorithm is based on the inherent phase difference information in the heterodyne signals, and operates without any additional optical or electrical components. An optical scanning holography setup was created using a heterodyne frequency of 4 MHz with a 500‐mm distance and 5‐mm depth resolution. The reconstruction processing time was measured to be 0.76 s, showing a 62% time reduction compared to a recent study.

We propose simple distance extraction algorithm for hologram reconstruction in optical scanning holography. By measuring the time-of-flight of the heterodyne beam in optical scanning holography, we can extract the depth information from the object apart by an arbitrary distance. For the timeof-flight, we has constructed the scanning holography and then, we extracted the phase information by using lock-in-amplifier without an additional changes in basic scanning holography setup. Finally, we have reconstructed the reflection-type complex hologram about 10.4mm x 10.4mm object apart from 426mm by this method.