January 14, 2020
Spectrograph from a CDROM
The are a lot of simple projects illustrated online that show how to make a spectrograph
from a discarded CDROM.
It turns out that the track spacing on a CDROM is about 1.6 microns, which yields
625 lines per millimeter.
A DVD has about twice as many (1250 lines per millimeter).
A note here about words. A spectrograph is what most people make.
It is something you can look through and see a spectrum.
A spectrometer is a quantitative instrument.
In this day and age it should yield digital data
(i.e. a spectrum with intensities as a function of frequency).
More general designs
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Tom's Electronics pages / tom@mmto.org