Wave Optics - Resolving An Image
Description:
Resolution
Resolution is the measure of clarity of an image i.e. identifying distinguishable objects in an image. The minimum distance between these closely placed objects that can be distinguished as separate objects is known as MINIMUM DISTANCE OF RESOLUTION.
Resolving Power
Resolving power is the measure of any optical instrument to identify two closely placed distinct objects, It is dependent on the minimum distance of resolution.
Resolving power = 1 / minimum distance of resolution
This implies - The resolving power of any instrument is greater if the minimum distance of resolution is small for that instrument.
Resolution and Diffraction
The reason we cannot distinguish two separate objects in an image that have distance less than minimum distance of resolution is diffraction.
We observe two separate patterns on the screen generated by both the individual objects.
If the central maxima of individual patterns do not overlap and there is a clear dark patch between both the central maxima, then it is known as RESOLVED (i.e. both the objects can be distinguished).
If the central maxima of individual patterns overlap and there is no dark patch between both the central maxima then it is known as NOT-RESOLVED (i.e. both the objects cannot be distinguished).
If the central maxima of one pattern falls exactly on the first dark point of second pattern, then it is known as JUST-RESOLVED (i.e. both the objects are just hardly distinguished). This is known as RAYLEIGH CRITERION.
