Names: Tung H. Jeong, Masashi Iwasaki,
and Raymond Ro
Address: Lake Forest College, Department of Physics, 555
N. Sheridan Road,
Lake Forest, IL 60045, USA
Telephone: 847-234-3756
Fax: 847-234-615-0835
E-mail: tjeong@aol.com
Lecture-Demonstration or Advanced Laboratory and Low-Cost
Lecture-Demonstration or Advanced Laboratory
and
Low-Cost
Support Required None
Approximate Size 3x4feet
Does this apparatus require electrical power? No
Will you be present to set up your apparatus? No. We will NOT be present to set up the apparatus. We will ship it in three cartons. Inside, there will be detail instructions, with photographs, on how to set it up. Everthing is pre-mounted. Please have your staff set it up before. The equipment needed for setting up a knife (for opening the cartons), and maybe some glue and tapes in case something got loose from shipping.
Use of the Elliptical Beam from a Diode Laser to Make Panoramic Holograms
Abstract
New diode lasers sold as "pointers" have long coherence lengths. By removing the collimating lens, the output fans out in a highly eccentric elliptical profile which allows one side to serve as reference beam and the other side as object beam. Without using any optical elements, we can make very bright and panoramic transmission holograms on a sand box. For more advance laboratory exercises and lecture demonstrations, the addition of a mirror and a ground glass allows one to make more advanced holograms and perform holographic interferometry on phase objects.
Description:
Holographic experiments are very illustrative for understanding
modern optics. Now, low cost "laser pointers" are available as
a light source for making holograms. But using a laser pointer requires
an optical component (lens or curved mirror) in order for the beam to diverge.
The required optical component is expensive. Furthermore, the collimated
light can cause eye injuries. By removing the collimating lens from a diode
laser, the light from the laser spreads out in a highly eccentric elliptical
shape with no interference or diffraction patterns. It is suitable for
making high-quality white light viewable reflection holograms without additional
optical components (Figure 1) .
Figure 1.
Because of the long coherence length of diode lasers, along with "safer" processing chemicals (JD-3) that do not cause shrinkage of the emulsion, deep-scene reflection holograms can be recorded. The finished hologram is viewable with the same diode laser or a point source of incandescent light. By orienting the elliptical beam horizontally, wide-angle (panoramic) transmission holograms can be recorded without the use of optical components (Figure 2).
Figure 2.
By adding a mirror, transmission holograms of frontally illuminated objects can be made (Figure 3). These holograms appear to be brighter than side-lighted transmission holograms. For the advanced class, time-averaged or double-exposure holographic interferometry can be performed by using a rigid table.
Figure 3.
Figure 4 shows a configuration for recording a transmission
hologram of a ground glass. When the finished hologram is repositioned
at the location where is was recorded, the viewer sees both the real object
(ground glass) and the virtual image of the object. Light from the object
interferes with the virtual image if the path of the object light is deviated
(or r<