Angular Resolution Calculator

Angular Resolution Calculator

Calculate the minimum angular separation between two objects that can be distinguished using the Rayleigh criterion.

Angular Resolution Analysis

Angular Resolution
1.3840 arcsec

What is Angular Resolution?

Angular resolution is the ability of an optical system to distinguish between two closely spaced objects as separate entities. It defines the minimum angular separation required to resolve two point sources.

The Rayleigh criterion is the standard defining angular resolution. Two point sources are just resolved when the central maximum of one diffraction pattern coincides with the first minimum of the other. This theoretical limit is determinedby wavelength and aperture size.

Larger instruments and shorter wavelengths provide better resolution, which is why telescopes are so large and electron microscopes achieve such magnification.

How to Calculate

θ = 1.22 × λ / D

Where: θ = angular resolution (rad), λ = wavelength (m), D = aperture diameter (m), 1.22 = Bessel function constant

Example

Telescope with 1 meter mirror observing visible light (550 nm)

θ = 1.22 × (550 × 10⁻⁹) / 1 = 6.71 × 10⁻⁷ rad ≈ 0.138 arcsec

FAQ

Why is larger aperture better?

Larger D means smaller θ (better resolution). This is why professional telescopes have such large mirrors.

Does shorter wavelength improve resolution?

Yes, shorter λ yields smaller θ. Ultraviolet telescopes see finer details than infrared; electron microscopes beat optical microscopes.

What does 1.22 represent?

It's the first zero of the Bessel function J₁, derived from wave diffraction theory for circular apertures.

Can we beat the Rayleigh limit?

Not with individual apertures. Advanced interferometry combines light from multiple telescopes to achieve better effective resolution.

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