IPhO-37_Th3-solve - SOLUTIONS to Theory Question 3 Digital...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Digital Camera Two factors limit the resolution of the camera as a pho- tographic tool: the diffraction by the aperture and the pixel size. For diffrac- tion, the inherent angular resolution θ R is the ratio of the wavelength λ of the light and the aperture D of the camera, θ R = 1 . 22 λ D , where the standard factor of 1 . 22 reflects the circular shape of the aperture. When taking a picture, the object is generally sufficiently far away from the photographer for the image to form in the focal plane of the camera where the CCD chip should thus be placed. The Rayleigh diffraction criterion then states that two image points can be resolved if they are separated by more than 3.1 Δ x = R = 1 . 22 λ F], which gives Δ x = 1 . 22 μ m if we choose the largest possible aperture (or smallest value F] = 2) and assume λ = 500 nm for the typical wavelength of daylight The digital resolution is given by the distance ` between the center of two neighboring pixels. For our 5 Mpix camera this distance is roughly ` = L q N p = 15 . 65 μ m . Ideally we should match the optical and the digital resolution so that neither aspect is overspecified. Taking the given optical resolution in the expression for the digital resolution, we obtain 3.2 N = ± L Δ x ² 2 823 Mpix . Now looking for the unknown optimal aperture, we note that we should
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 5

IPhO-37_Th3-solve - SOLUTIONS to Theory Question 3 Digital...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online