|
The standard incandescent bulbs I mentioned were calibrated with respect to standard bulbs maintained by the NBS, and originally traced back to the definitive standard consisting of a black-body cavity in a piece of platinum at a specified temperature
Today, of course, instruments use stable solid state silicon photodetectors. I believe (but don't quote me, have to research it) the base standard now consists of lasers whose output can be measured accurately thermally and then transferred to a standard photodiode and from there to secondary standards.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Last edited by old_tv_nut; 01-01-2026 at 09:23 PM.
|
01-01-2026, 01:38 PM
Threaded Mode