Re: Color Lab

[Marlyn Jakub <mjakub@PHYSICS.OTAGO.AC.NZ>]

At 08:57 AM 4/18/01 -0400, Tim O'Donnell wrote:
> Does any one have any lab involving colors.
> I have a lot of colored cellophane.
> I have a few colored light bulbs.
Tim,

I have used the following equipment to turn white light (from a small
halogen lamp) into the full three-circle color wheel using only clear glass
transmission:
1 >50W halogen lamp inside an air-cooled metal can with a hole (~1.5cm ID)
2 black opaque screens with ~1.5cm ID holes for masking the light beam into
a circle.
2 ~2.5cm wide glass prisms (used in series to disperse the white beam)
1 ~10cm OD convex glass lens to converge the beam into a color line.
1 15degree wedge prism cut into ~0.6cm width and >2cm width pieces. The
pieces are then glued onto a thin plate glass at an angle of about 50
degrees so that the smaller width shifts the red end of the color line and
the wider piece shifts the blue end of the line (it is wider after
dispersion). I suggest trying the wedge arrangements before gluing the
pieces together at ends away from where the line crosses the glass segments.

The results, after fiddling with the various parts for spacing arrangements,
show white light circle until the wedges are place into the beam. (An
optical bench mounting arrangement is suggested to make spacing rather
permanent and quick for this step) Presto...the color circles appear R-G-B
with complementary overlap colors and white in the center...just as shown in
the textbooks!

Marlyn Jakub