Image aberrations

Because it is concave and elliptical, the secondary mirror of a Gregorian telescope allows for simpler fabrication test set-ups, as a point-like source placed at one of the foci of the ellipse should be re-imaged aberration-free at the other focus. Convex hyperbolic mirrors require more complex set-ups. This disadvantage is usually more than balanced by the more compact arrangement, the savings implied by the shorter telescope structure and more compact enclosure offsetting the additional cost and complexity of the secondary mirror test set-up. This trade-off, however, applies in the context of current technology-... 

Chapman, L. ]., Chapman, ]. P.,. Raulin, M. L. (1978). Body-image aberration in schizophrenia. Journal of Abnormal Psychology, 87, 399-407. 

Figure 8.2 The use of adaptive optics to correct image aberrations.

Figure 8.2 The use of adaptive optics to correct image aberrations, (a) Astronomy Neptune observed in the near-IR (1.65 pm) with and without adaptive optics. (Credit C.E. Max et al., reproduced by permission of the America Astronomical Society), (b) Vision science imaging of individual rods and cones in the living human retina. (Credit Y. Zhang, S. Poonja, and A. Roorda, reproduced by permission of the Optical Society of America.)...

The ion beam width (w ) at the image position is related to the ion beam width defined by the source slit (t g), the image lateral magnification (M) and the sum of the imaging aberration coefficients (a) by ... 

Thus, the mass dispersion coefficient and the slit widths are the most significant parameters in setting the resolution, and the ratio of dispersion to magnification [DJM) is a key figure of merit in the design of an instrument. However, ultimate resolution is limited by the imaging aberrations. 

TABLE II Basic Image Aberrations Occurring in Telescopes... 

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