Light: Polarisation and Diffraction


The direction of an electromagnetic wave’s electric field vector is referred to as the polarisation of light. The electric field vector oscillates in every feasible plane perpendicular to the direction of propagation in an unpolarized light wave. In contrast, the magnetic field oscillates perpendicular to the electric field in a polarized light wave whereas the electric field vector oscillates in a specified direction or plane.

Many different processes, including reflection, refraction, and scattering, can result in polarisation. Based on the polarisation state of the light waves, polarizers are tools that may selectively transmit or block the light waves.

Optics is just one of the many industries where polarisation has valuable uses. For instance, optical microscopy can benefit from the use of polarized light to boost contrast and enhance picture quality.

Polarisation in photography is the process of selectively transmitting or blocking polarized light waves using a polarizing filter. A polarizing filter is made of a substance that only lets through light waves with a specific direction of polarisation while blocking all other polarisations.

Outdoor photographers sometimes employ polarizing filters to lessen reflections and glare from non-metallic surfaces like water, glass, and plants. Polarizing filters can enhance the color saturation, contrast, and clarity of the final image by obstructing polarized reflections.

Polarizing filters can improve the look of skies by making the clouds more noticeable and the sky appear bluer. Moreover, polarizing filters can be utilized to provide distinctive effects like lessening haze’s appearance or highlighting a certain surface’s texture.


The bending and spreading out of light waves as they move through a small space or around a barrier is known as diffraction of light. A diffraction pattern can be seen on a screen or detector when light waves contact an obstruction or aperture that is equivalent in size to their wavelength.

The size, shape, wavelength, and distance between the obstacle or aperture and the screen or detector are only a few of the variables that affect the diffraction pattern that light waves produce. Bright and dark fringes or bands make up the pattern, which is caused by the interference of constructive and destructive light waves.

Diffraction is a phenomena that can affect how clear and sharp an image appears in photography. The image seems less clear and detailed when light is allowed to enter through a tiny aperture, like the aperture of a camera lens.

The degree of diffraction depends on how large the aperture is in relation to the light’s wavelength. A softer, less-detailed image results from an increase in diffraction as the aperture size lowers. When utilizing tiny apertures, such as f/16 or f/22, where diffraction can lessen the overall sharpness of the image, this effect can be particularly apparent.

Photographers can choose a bigger aperture, such as f/8 or f/11, to increase light entering the lens and produce a sharper image, minimizing the effect of diffraction on image quality. Even at smaller aperture settings, utilizing a higher-quality lens with better optics can lessen the effects of diffraction and create clearer photos.

In general, photographers who wish to produce the sharpest, most detailed photographs possible must understand the effects of diffraction. Photographers can reduce the effects of diffraction and create high-quality photographs by selecting the appropriate aperture settings and equipment.