Progress on international optics standards

Significant progress was made at the May 12 to 15 meeting of ISO/TC 172/SCI, Optics and Optical Instruments/Fundamental Standards held in Thun, Switzerland. Optical testing is the concern of Working Group 1 (WG1), which has been concentrating on standards for OTF (or MTF) testing of various types of lenses. In addition to recently published draft proposals on OFT-Definitions and mathematical relationships and OTF-Principles and procedures of measurement, WG1 approved draft proposals for submission to the Secretariat on OTF testing of 35mm camera lenses, office copier lenses, and telescopes.

by Robert E. Parks

The greenhouse effect: radiant transmittance of glass

The equipment shown in the photo is used to introduce students to the theory of the Greenhouse Effect. With the energized soldering iron placed several feet in front of the radiation thermopile, one obtains full-scale deflection on the galvanometer. A lab jack is then used to support a piece of high quality optical glass (about 1" thick) that is large enough to completely cover the reflecting cone associated with the radiometer.

by J.H. Taylor