What factors limit the resolution in optical systems?

The resolution in optical systems is primarily limited by diffraction, aberrations, and the quality of the optical components used.

Diffraction is a fundamental limit to the resolution of any optical system. It is a phenomenon that occurs when light waves encounter an obstacle or a slit that is comparable in size to its wavelength. This causes the light to bend and spread out, leading to a blurred image. The smaller the aperture of the system, the greater the diffraction and the lower the resolution. This is described by the Rayleigh criterion, which states that two point sources can be resolved if they are separated by an angle greater than the diffraction limit.

Aberrations also limit the resolution of optical systems. These are deviations from the ideal image, caused by the imperfect shape or alignment of the optical components. There are several types of aberrations, including spherical aberration, chromatic aberration, and astigmatism. Spherical aberration occurs when light rays at different distances from the optical axis are focused at different points, leading to a blurred image. Chromatic aberration is caused by the dispersion of light into its constituent colours, which are focused at different points. Astigmatism occurs when the system has different focal lengths in different planes.

The quality of the optical components used in the system can also affect the resolution. This includes the quality of the lenses and mirrors, as well as the detectors used to capture the image. High-quality components are designed and manufactured to minimise aberrations and maximise the resolution. However, even the best components cannot overcome the fundamental limit imposed by diffraction.

In addition, the resolution can be affected by environmental factors such as temperature, pressure, and humidity, which can cause the optical components to expand or contract, altering their shape and alignment. Furthermore, the resolution can be limited by the signal-to-noise ratio, which is the ratio of the signal power to the noise power. A high signal-to-noise ratio means that the signal is strong compared to the noise, leading to a clearer image.

In conclusion, the resolution in optical systems is limited by a combination of diffraction, aberrations, the quality of the optical components, and environmental factors.