I'm going to describe a physics experiment involving imaging a proton beam using a CCD camera by reflecting it on a aluminium oxide surface, and we need some help about how close the camera should be to the surface (aluminium oxide) in order to get the best resolution.
Note that, from the point of view of the analyst of those images, the closer the camera to aluminium oxide surface, the less error that those data contains.
Description of the setup:
Note: The angle of the surface with the horizontal plane is 45 degree.
What we need exactly from those images:
The following image is one of the example that we are taking;
(The vertical size of the seen ellipse is 4cm only)
Although, we are taking RGB coloured images from the camera, we are transforming those images to gray scaled from because the only thing that we need from them is the brightness values that is contained in each pixels.
Now the thing is, we would like to make the CCD camera close to the surface as much as possible; however, in this case, would we lose any resolution ?
To be clear, for a given focal length f and lens size of a CCD camera, what is the smallest distance that the camera should be located from the surface such that we get the maximum resolution that we can ?
Secondly, if we want to decrease that distance or increase the resolution, why type of cameras or lenses should we use ?
As I have mentioned in the "background" part of the question above, the only that we need need from those images are the brightness values, i.e the luminance, contained in each pixel. Moreover, we do not use the hue and saturation information contained in those images, only luminance.
we just want to measure the size of the beam, and the aluminium oxide surface is used a way to reflect the beam to the camera.