All posts tagged: Nobel Prize

Introduction to Holography skepticsociety.co.uk

Introduction to Holography

If you’re carrying money, a drivers license, or credit cards, you’re carrying around holograms. The dove hologram on a Visa card may be the most familiar. The rainbow-colored bird changes colors and appears to move as you tilt the card. Unlike a bird in a traditional photograph, a holographic bird is a three-dimensional image. Holograms are formed by interference of light beams from a laser. HOW LASERS MAKE HOLOGRAMS Holograms are made using lasers because laser light is “coherent.” What this means is that all of the photons of laser light have exactly the same frequency and phase difference. Splitting a laser beam produces two beams that are the same color as each other (monochromatic). In contrast, regular white light consists of many different frequencies of light. When white light is diffracted, the frequencies split to form a rainbow of colors. In conventional photography, the light reflected off an object strikes a strip of film that contains a chemical (i.e., silver bromide) that reacts to light. This produces a two-dimensional representation of the subject. A …