One of the main factors driving improvements in the cost and complexity of integrated circuits (ICs) is improvements in photolithography and the resulting ability to print ever smaller features. Modern circuits are made using a variety of complicated lithography techniques, with the goal to make electronic traces as small and as close to each other as possible (to reduce the overall size, and thus increase the speed). In the end though, all optical techniques are limited by diffraction.
Assume we have a scannable laser that draws a line on a circuit board. Assume the laser wavelength is 248 nm (Krypton Fluoride excimer laser), the initial beam diameter is 1 cm, and the focusing lens (diameter 1.3 cm) is extremely fast', with a focal length of only 0.625 cm.
What is the approximate width w of the line (defined here as the distance between diffraction minima on either side of the central spot/ridge)?