Dr Rajiv Desai
An Educational Blog
HOLOGRAM
HOLOGRAM: _____ Typical laser-lit transmission hologram ____ Prologue: Suppose you want to take a photograph of an apple. You hold a camera in front of it and, when you press the shutter button to take your picture, the camera lens opens briefly and lets light through to hit the film (in an old-fashioned camera) or the light-sensitive CCD chip (in a digital camera). All the light traveling from the apple comes from a single direction and enters a single lens, so the camera can record only a two-dimensional pattern of light, dark, and color. To be more accurate camera records wave length (color) and intensity (amplitude) of light waves. If you move your head slightly, the photograph remains same i.e. it is two dimensional. The physical world around us is three-dimensional (3D), yet traditional display devices can show only two-dimensional (2D) flat images that lack depth (i.e., the third dimension) […]
Closed-Circuit Television (CCTV)
Closed-Circuit Television (CCTV): ________ CCTV pictures showing Al Qaeda’s terrorists Mohamed Atta and Abdulaziz Alomari boarding a 6:00 a.m. flight from Portland to Boston’s Logan International Airport on September 11, 2001. _____ CCTV footages of 2015: _______ Prologue: In the past people didn’t misbehave because they thought God was watching them. Today we’ve replaced an all-seeing God with the glassy eye of the CCTV camera. A CCTV camera can operate 24 hours a day, seven days a week, and 365 days a year without a toilet break or lunch. It does not need a holiday, maternity leave and rarely goes sick. There were 25 million CCTV cameras in operation worldwide, with 2.5 million in the UK in 2002 but today the figure is doubled. Practically every major city now boasts a CCTV system aimed at, among other things, preventing, detecting and reducing crime. Increasingly these developments are mirrored in villages, […]
