Waves of all types inevitably spread out while propagating, owing to diffraction. Under certain strict conditions, however, waves can be made to propagate without diffraction. Although this has been ...

Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences, Vol. 209, No. 1096 (Oct. 8, 1951), pp. 81-96 (16 pages) The radio waves from 'radio stars' may suffer ...

Please provide your email address to receive an email when new articles are posted on . Vision is the perception of light. To comprehend the nature of human vision, an understanding of the properties ...