The purpose of the reference beam is to provide the recording device with information such as background light, picture angle, and beam profile.
22.
The difference between the reference beam and the sampling beam thus reveal the properties of the sample in the way it scatters light.
23.
If it is decided to produce optical dispersion ) would be placed in the path of the reference beam to match the test cell.
24.
The reflecting surfaces of the beam splitters would be oriented so that the test and reference beams pass through an equal amount of glass.
25.
The beam from the laser, which has a frequency f o, is divided into a reference beam and a test beam with a beamsplitter.
26.
In one common arrangement, the laser beam is split into two, one known as the object beam and the other as the reference beam.
27.
When it reaches its target, the modified signal beam collides with the reference beam, causing an interference pattern that is recorded to produce the hologram.
28.
This contains a stepping mirror that shifts the reference beam, which is then processed with a best fit-algorithm and presents the information in real time.
29.
This effect is of greater concern for in-line holographic systems because the reference beam is propagated through the volume along with the scattered object beam.
30.
The result is that light traveling an equal optical path length in the test and reference beams produces a white light fringe of constructive interference.
