For decades now, the laser has been used as a handy device for performing ray traces in geometrical optics demonstrations and laboratories.1, 2 For many ray- trace applications, I have found the laser level3 to be even more visually compelling and easy for student use than the laser pointer.

1.
E. D.
Noll
,
“Measuring the index of refraction of liquids with a laser: Experiment 2,”
Phys. Teach.
11
,
309
(May
1973
).
2.
J.
O'Connell
,
“Optics experiments using a laser pointer,”
Phys. Teach.
37
,
445
(Oct.
1999
).
3.
The Craftsman Laser Trac™ yields a particularly high-quality beam and its magnetic base makes it very useful for blackboard optics demonstrations; color blind students may benefit from the red-transmitting “safety” glasses included with these lasers. The Craftsman laser level is a 2.5-mW Class IIIa laser and intrabeam viewing should be avoided (see Chapter 6 of the OSHA Technical Manual on Laser Hazards, www.osha.gov/dts/osta/otm/otm_toc.html).
4.
J. J.
Lynch
,
“Snell's law with large blocks,”
Phys. Teach.
45
,
180
(March
2007
) suggests a source of large blocks of Plexiglas; the inch-thick slabs used by the author are available from Custom Creative Plastics, www.customcreativeplastics.com.
5.
R.
Newburgh
,
W.
Rueckner
,
J.
Peidle
, and
D.
Goodale
,
“Using the small-angle approximation to measure the index of refraction of water,”
Phys. Teach.
38
,
478
(Nov.
2000
).
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