Optics in Forensics Topics explored 27 March 2002

1) "Smoke and Mirrors" (geometrical optics)
   Light (and bullets) travel in straight lines and reflect 
   with equal angles to the perpendicular. Skit idea: use toy gun, 
   cutout or posed figure to demonstrate path of a bullet. Maybe 
   add a mirror to bounce the light (bullet) to another wall. 
   Would have to be perfected beforehand!

2) "Black light" (optical flourescence) 
   Use black light (really violet and UV) with special glasses
   that block the visible violet part. Anything that flouresces
   (stains, dried blood, special fingerprint powder) glows 
   brightly. We'll need to get some dayglo paint.

   I can order one of these battery operated UV lights!

   To learn more, seach on <"black light" forensics>.

3) "Magnifying Glasses" (geometrical optics, lenses)
   focussing "strength" or "power" is measured in diopters.
   One diopeter = 1/focal length in meters. Focussing strengths of
   adjacent lenses combine, so focal length of two identical
   lenses is half of either one alone, and focal power is double.
   Skit idea: combine two magnifying glasses to see better. 

   Cool web sites:



4) "Night Vision" (infrared light) 
    we have the night vision viewer ... skit idea: hide behind a 
    dichroic screen that blocks IR rays. 

5) Spectroscope ... analyze elements by the "fingerprint" of colors
   emitted. Detects atoms, not molecules. Could detect arsenic in
   hair samples (poison).

6) Is he dead? test. (Scattering of light in oxygenated tissue). See

7) Microscopy. Hair and fiber analysis, etc.