Transmission Hologram With Reference Beam

Experimenter: Chris Cleven

This is a trial setup for a transmission hologram with a reference beam. The light strikes the object from two directions. We modeled after a procedure developed by Dan Wright.

The holographic image below, with a die and a small plastic skull, was taken with an exposure time of about 40 seconds, whereas we had calculated 20 as the exposure which would give optimum density on the film.

The viewing angle was quite narrow, and at a fairly extreme angle as illustrated. 视角相当狭窄，在示意图中显示为一个相当极端的角度。

A discussion with Clay Turner brought the following comments about the procedure:

• We should make the path lengths for the reference beam and the object beam equal within about 2-3cm. The above images had a pathlength difference of approximately 15 cm.
  我们应该使参考光束和物体光束的路径长度在约2-3厘米范围内相等。上述图像中路径长度差约为15厘米。
• There should be the same number of phase reversals in each beam, since the laser light has time-random elliptical polarization. This means the same number of mirrors in each beam - we had one mirror in reference beam. In the object beam, one part of it came from the sapphire lens and one part from the concave aluminum-foil mirror.
  每个光束中应有相同数量的相位反转，因为激光光具有时间随机的椭圆偏振性。这意味着每个光束中应有相同数量的镜子——我们参考光束中有一个镜子。在物体光束中，一部分来自蓝宝石透镜，另一部分来自凹形铝箔镜。