Spectral resolution of a zoneplate with circular sensor.
The energy intercepted by a circular sensor exposed to panchromatic light from a point source transmitted by a zoneplate lens is expressed as the convolution of the spectral source distribution with a wavenumber spread function. This wavenumber spread function, which represents the monochromatic energy encircled by the sensor as a function of wavenumber, depends on the product of the number of zones and the distance between sensor and focal plane and is invariant for a constant ratio of sensor radius to Airy radius. Results obtained by the diffraction integral for sensor radii larger than or comparable with the Airy radius are compared with approximate expressions based on geometrical optics and with the analytical expression for the limiting case of sensor small compared with Airy radius. The dependence of the energy intercepted by the sensor on the halfwidth of a Lorentzian source distribution is described. Applications of the sensor-zone-plate lens combination to a scanning spectrometer and monochromator are discussed.
Fedotowsky
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Lehovec
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