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30 Aug 2002
The pick of this week's hottest patent applications in the world of photonics.
• The idea of an "invisibility cloak" has made the leap from science fiction books to an international patent application. Ray Alden of North Carolina is attempting to patent a "three dimensional cloaking process and apparatus" for concealing objects and people (WO 02/067196).
The idea hinges on carefully mimicking background lighting conditions to help render an object invisible, similar to how a chameleon blends in with its surroundings. The rear and front surfaces of an object are covered with a material containing an array of photodetectors and light emitters respectively.
The photodetectors on the rear surface are used to record the intensity and color of a source of illumination behind the object. The light emitters on the front surface then generate light beams that exactly mimic the same measured intensity, color and trajectory. The result is that an observer looking at the front of the object appears to see straight through it.
• Matsushita Electrical of Japan is patenting an easy and cost-effective way to erase the data on a CD-R disk (WO 02/067249). CD-Rs have become a popular method for recording computer and audio data, however, the data can only be written once and is considered permanent. Matsushita says that by irradiating the disk with a laser beam with a power equal to, or higher than, the power of the initial recording laser beam, the stored data can be erased. The technique may be useful for wiping confidential or sensitive data from a disk.
• The Penn State Research Foundation, US, has designed a wireless "one to many" communication system that makes use of multi-beam infrared transmitter. The invention, outlined in international patent application WO 02/067465, directs an array of infrared beams onto a reflecting surface. An array of receiving elements then detect the reflected IR beams. The transmitter may consist of a light source, collimating optics and a spot-array generator. Each of the receiving elements may include a bandpass filter, a concentrator and a photodetector.
Author
Oliver Graydon is editor of Optics.org and Opto & Laser Europe magazine.
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