The cornea, a boundary between the air and the aqueous humor, has a focal length when acting alone. What is its radius of curvature?
The radius of curvature is
We have given that:
The focal length is .
We need find out the radius of curvature.
By using formula:
From previous formula, Let us find R:
Here, and is the refractive index of the first and second medium respectively, is the focal length and is the radius of curvature.
The resolution of a digital cameras is limited by two factors diffraction by the lens, a limit of any optical system, and the fact that the sensor is divided into discrete pixels. consirer a typical point-and--shoot camera that has a lens and a sensor with pixels.
(a) . First, assume an ideal, diffractionless lens, at a distance of what is the smallest distance, in between two point sources of light that the camera can barely resolve? in answering this question, consider what has to happen on the sensor to show two image points rather than one you can use
(b) . You can achieve the pixel-limied resolution of part a only if the diffraction which of each image point no greater than the diffraction width of image point is no greater than pixel in diameter. for what lens diameter is the minimum spot size equal to the width of a pixel ? use for the wavelength of light.
(c). what is the of the lens for the diameter you found in part b? your answer is a quite realistic value of the at which a camera transitions from being pixel limited to being diffraction limited for smaller than this (larger-diameter apertures), the resolution is limited by the pixel size and does not change as you change the apertures. for larger than this (smaller-diameter apertures). the resolution is limited by diffraction and it gets worse as you "stop down" to smaller apertures.
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