Modern Physics > Quantum Effects > Wave Mechanics
 DCS# 7A50.10
FRUSTRATED TOTAL INTERNAL REFLECTION
  
APPARATUS
laser
 202-21-B6
two refraction blocks
 202-21-E4
drill press vise
 007
camera or document camera
 202-09-D

DESCRIPTION
The refraction blocks are mounted in a vise.  Aim the laser so the light is totally internally reflected in the first block.  Tighten the vise to reduce the gap between the blocks until a transmitted beam from the laser can be seen passing through the second block.  This illustrates optical barrier penetration, analogous to quantum tunneling for particles.  It also shows how cube beam splitters work.
NOTES
Setup:

 

Block faces must be very clean.  Use soap and water, not alcohol.

Use the vise from the student shop with flat-faced jaws (one may need to be reversed), and protect the blocks with a couple of pieces of lens paper.  The 1/4" thick piece of plexiglas (202-21-E4) brings the blocks to the correct height.

REFERENCE

AJP, 33, # 5, May 1965, p.xviii.