14 Apr 2005
The pick of this week's patents including laser apparatus for spotting submarines.
• Title: Method and apparatus for detecting submarines
Applicant: BAE Systems Information and Electronic Systems Integration, US
International application number: WO 2005/026661
BAE Systems has devised a method of detecting submarines that involves projecting pulsed laser light down through a column of water and monitoring the resulting backscattered light or speckle. The set-up relies on spotting the violent movement of particles in a submarine's wake against a background of Brownian motion, which has sufficiently different dynamics. To achieve this, laser pulses are spaced at 10 to 100 microsecond intervals and the returning speckle patterns are imaged on a detector array and cross-correlated.
• Title: Method and apparatus for labeling using diffraction grating-based encoded optical identification elements
Applicant: Cyvera Corporation, US
International application number: WO 2005/027031
Tagging items with labels containing tiny diffraction gratings could provide a convenient and secure way to track raw materials and manufactured products according to the US firm Cyvera Corporation. Existing technologies such as bar codes, electronic microchips or radio-frequency identification can be too large for some applications or unable to withstand certain hostile environments say the authors of application number WO 2005/027031. Their design, comprising a diffraction grating sandwiched between two optical substrates, provides a unique identification code when illuminated by incident light. The code, which takes the form of spatially distributed light, can be collected and analyzed. According to its inventors, the grating element provides more than 67 million unique codes and is able to withstand harsh conditions.
• Title: LED disinfecting lamp
Applicant: Koninklijke Philips Electronics, The Netherlands
International application number: WO 2005/031881
Electronics giant Philips is attempting to patent a mercury free, low-voltage disinfecting lamp that uses ultraviolet (UV) LEDs emitting over the 250 - 280 nm wavelength band. "The germicidal action curve shows that the maximum germicidal action is obtained from UV light with a wavelength of 265 nm," said the applicants. The Philips scientists mix different semiconductor compounds such as InN, InGaN, AlN or AlGaN to create an LED with a conduction band of approximately 4.7 eV and an emission wavelength of 265 nm.