Question

In holography which of the following is/are recorded in photographic film?

• A. Phase only
• B. Amplitude only
• C. Phase and amplitude
• D. Frequency and amplitude

Answer 1

Answer: (C)

Phase and amplitude

Holography is a method to record both the amplitude and the phase information in the light wave that reaches the film. The first step is the recording of the interference pattern formed between the sample beam, which diffusely reflects from the object and the reference beam which is sent directly to the film. These two beams must be coherent and are normally obtained from a single laser by splitting its beam. The idea behind this method is to capture the full information present in the light waves of the sample beam as they arrive at the detector using the reference beam as a way to store not only the amplitude information, but also the phase information.

When the film is developed (the developed film is called the hologram) and examined directly by eye, it does not look at all like a normal photograph, but is simply a complex interference pattern of light and dark bands in complex shapes and bears no direct resemblance to the original objects.