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Nicol Prisms
A Nicol Prism is a device to produce polarized light. It is made from a crystal of calcite, which is cut along a precisely determined plane and then cemented back together with Canada balsam. When a beam of light enters the crystal along the line defined by the mounting of the crystal, it is broken into two beams. In the two beams the planes of vibration of the electric field vector are perpendicular to one another. When the two beams strike the cemented cut, one is passed through and the other is deflected to the side and absorbed in the mounting.
Laser
This is the first laser owned and used by the Grinnell College Physics Department. It is a helium-neon laser, and the gas inside the tube was excited by a radio-frequency field produced by an oscillator. This laser was purchased by Bob Noyce, who experimented with it for a short time and then brought it, carried on his lap on the airplane, to Grinnell and presented it to the Physics Department. The orange plastic cover is lying behind the instrument.
Lens on Stand
This lens on a ball mount has been used for many years for lecture demonstrations. Although neither date of purchase nor maker is known, it certainly has been part of the college's equipment since the early 1900s if not earlier.
Prism with Variable Angle
This prism with variable angle was used to study how the angle of deviation of a beam of light increases with the refracting angle of the prism. The glass plates which make up part of the prism can move about their hinged bottom edge. Water is placed in the prism, a beam of light is directed through it, and then the angle of the prism can be changed by sliding the glass between the brass sides.
