Asian Journal of Physics Vol 30, No 1  (2021) 31-43

Resolving power of optical instruments: A Tutorial*

Rajpal Sirohi
Alabama A&M University, Huntsville AL 35802
Dedicated to Professor M S Sodha for his numerous contributions to
Plasma Physics, Optics and Photonics, Energy Studies and Education Management

Optical instruments are used for observation and spectroscopy apart from host of many other applications. Both in observation and spectroscopy it is important to know how closely two objects, or two spectral lines can be resolved by the instruments. There had been a number of criteria of resolution: two most often used are Rayleigh criterion and Sparrow criterion. Rayleigh criterion of resolution has no mathematical support but is often used due to its simplicity. Sparrow criterion gives the lowest limit of resolution. Further in seeing, the nature of illumination of the object has profound effect on the limit of resolution. Rayleigh criterion tacitfully assumes incoherent illumination, while the Sparrow criterion can be applied to incoherent, partially coherent and coherent illuminations. Applicability of Rayleigh criterion can be extended to partially coherent and incoherent illuminations by a simple modification. The paper through the tutorial approach describes the resolution of optical instruments used for seeing and spectroscopy. © Anita Publications. All rights reserved.
Keywords: Resolution, Telescope, Microscope, Fabry-Perot, Grating, Resolving Power

DOI: 10.54955.AJP.30.1.2021.31-43

Peer Review Information
Method: Single- anonymous; Screened for Plagiarism? Yes
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