Nine articles in three areas. Each links to its area and to the full guide.
A lens with a circular aperture does not focus a point of light to a perfect point. Diffraction spreads the light into a pattern: a bright central...
Read article → ArticleA lens usually performs best at a middle aperture. Wide open, aberrations such as spherical aberration and coma are strongest, because light passes...
Read article → ArticleThe diffraction limit is the smallest detail a perfect lens can resolve, set by the wavelength of light and the size of the aperture. Because light...
Read article →A simple spherical lens focuses light from its edge to a slightly different point from light passing through its centre. This difference blurs the...
Read article → ArticleThe modulation transfer function (MTF) describes how much contrast a lens transmits at each level of detail. The horizontal axis is spatial...
Read article → ArticleThe refractive index of a material is the ratio of the speed of light in vacuum to its speed in the material. Glass used in lenses typically has an...
Read article →When two waves meet, their displacements add. If the peaks of both waves line up, the result is a larger wave. If a peak meets a trough, the result...
Read article → ArticleLight travels more slowly in glass than in vacuum. The speed in the material is c divided by the refractive index n. The frequency of the light does...
Read article → ArticlePixel pitch is the distance from the centre of one pixel to the centre of the next. A sensor with a pitch of 4 micrometres records detail in steps of...
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