Re: "Colorimeter"

On 5/18/2025 2:15 PM, Liz Tuddenham wrote:

Don Y <blockedofcourse@foo.invalid> wrote:
 

On 5/17/2025 2:03 PM, Liz Tuddenham wrote:

Don Y <blockedofcourse@foo.invalid> wrote:
>
>

How can I determine the spectrum of incident light on a sensor,
in general?  Then, how many corners can I cut to sacrifice resolution
and accuracy?

>
Spinning or oscillating prism?

>
That might be better than a varied filter.  But, probably require finer
control (or sensing) of its current orientation.

 If it is spinning steadily, all you need is a synchronising pulse at
some point once per revolution and a wide spectrum photocell with an
optical slit and a lens.  Software can work out the wavelength from the
rotational speed and the known characteristics of the prism.  The

Of course.  But, if spinning faster than your integration interval,
I suspect any jitter in your angular resolution might be difficult
to factor out of the mix.
This would, instead, suggest a slower rotation so the prism feeds
the detector a single wavelength for a longer (continuous) period.
That means the time to get a sampling of the spectrum is multiplied
by the integration interval.  If, instead, you could get "quick peeks"
at each wavelength "quickly", and the more precise integration "later",
you have more data to work with, sooner.
[This is the approach I have historically taken with data acquisition
as it lets me trade response time for resolution, dynamically]

resolution can be as coarse or as fine as you like and algorithms can
work out the visual perception of line spectra (if that is what you
need).
 The same hardware could be used for an expensive high-resolution device
or a cheap and cheerful version - the software and the time to reach a

"cheerful"?

steady reading (longer integration period for lower 'noise') being the
only real differences.