On 11/22/2011 06:59 AM, Nathan McCorkle wrote:
>> With that in mind, consider very narrow slits, and compensate for the
>> > dimming by
>> > integrating over time. You can also do HDR by taking several images and
>> > combining
> With longer integration times I feel that dark currents would start to
> blur the image to where it couldn't be ignored. Maybe not
The way to think of random noise integration is the dark current is
an amplitude of light per time just like the signal you are viewing.
Integrating makes both larger and smooths out low frequency noise ( 1/f noise).
So you do an integration long enough to get more light collected at your
imager pixel so it's within the manufacturer's recommended range.
That won't help for low levels similar to the dark current.
A narrow slit with strong light won't be that bad.
Only the astronomers wait for hours staring at regions of cosmos with lN2
cooling so the dark current is lower. You'll be integrating for milliseconds.
On 11/22/2011 06:59 AM, Nathan McCorkle wrote:
> First, you could simply eliminate focusing altogether, by having the optics
>> focus on infinity. The slit then looks like a point source at infinity, and
>> is
>> always in focus.
What does the sketch of that look like? A cylinder lens and correcting
lens close to the detector? Close to the slit seems like a good place
to stop spread...
Oh, here's an idea -- Some optical fiber has different refractive index per radial distance
from center and the effect is to funnel an input cone of light into smaller
bounce angles as it travels down the pipe, and exits with a narrower cone angle.
That's what to use for input fiber.
John
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