Tuesday, November 24, 2009

prototype 01


flash LED light projected onto a CD and reflected onto a ceiling

prototype 02


diffraction grading onto a ceiling or a floor.

materials


a LED lantern and CDs

reflected image


I love this image of reflection. I'm going to put a camera onto this image and show it through a small screen aside.

Interference patterns from a diffraction grating


Interference patterns from a projector transmitting light through a diffraction slide, creating different orders of the visible spectrum. The demonstration was carried out by the Harris Academy physics department on the open evening on 20 November 2008.

diffraction grating


Spectrum of white light by a diffraction grating. With a prism, the red end of the spectrum is more compressed than the violet end.
Courtesy of Bausch & Lomb, Inc., Rochester, N.Y.

diffraction grating

In optics, a diffraction grating is an optical component with a regular pattern, which splits and diffracts light into several beams travelling in different directions. The directions of these beams depend on the spacing of the grating and the wavelength of the light so that the grating acts as the dispersive element. Because of this, gratings are commonly used in monochromators and spectrometers.

A photographic slide with a fine pattern of black lines forms a simple grating. For practical applications, gratings generally have grooves or rulings on their surface rather than dark lines. Such gratings can be either transparent or reflective. Gratings which modulate the phase rather than the amplitude of the incident light are also produced, frequently using holography.

The principles of diffraction gratings were discovered by James Gregory, about a year after Newton's prism experiments, initially with artifacts such as bird feathers. The first man-made diffraction grating was made around 1785 by Philadelphia inventor David Rittenhouse, who strung hairs between two finely threaded screws. This was similar to notable German physicist Joseph von Fraunhofer's wire diffraction grating in 1821.
from Wikipedia

Monday, November 23, 2009

Flourescent light reflected


A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful light more efficiently than an incandescent lamp. Lower energy cost typically offsets the higher initial cost of the lamp. The lamp is more costly because it requires a ballast to regulate the flow of current through the lamp.

While larger fluorescent lamps have been mostly used in commercial or institutional buildings, the compact fluorescent lamp is now being used as an energy-saving alternative to incandescent lamps in homes. Compared with incandescent lamps, fluorescent lamps last longer, but are bulkier, more complex, contain trace amounts of mercury, and have poorer color rendition.
from wikipedia

Flourescent light reflected


Light from a fluorescent tube lamp diffracted by a CD shows the individual bands of color.
by wikipedia