Sparrow's resolution limit is the mathematical value derived from the Sparrow criterion, specifying the minimum resolvable separation between two point sources. For a circular aperture, it is calculated as 0.47 times the wavelength divided by the numerical aperture, which is roughly 20 percent smaller than the Rayleigh limit. Optical engineers use this limit when designing high-resolution imaging systems where pushing the absolute boundary of diffraction is necessary.
The specs claim a resolution of 200 nanometers, which means they're calculating based on Sparrow's resolution limit rather than Rayleigh.
Related terms
Sparrow criterion
A resolution limit defined by the point where the dip between two overlapping diffraction patterns disappears.
Rayleigh's resolution limit
The minimum separation required between two point sources for an optical system to distinguish them as separate.
Angular aperture
The angle subtended by the edge of an optical element as measured from the focal point.