13 Jan 2004
The pick of this week’s patent applications including a white LED based on zinc selenide.
• Title: Semiconductor light-emitting device
Applicant: Sumitomo Electric Industries, Ltd, Japan
International application number: WO 04/004018
Japanese firm Sumitomo Electric Industries is trying to patent a white LED based on zinc selenide (ZnSe). According to the application, the device is based on an n-type ZnSe substrate which contains self-active luminescence centers. An active layer is fabricated on top of the substrate and an aluminium layer reflects light out of the device. Sumitomo says the device’s luminance is high and that the color of the white light can be adjusted easily.
• Title: Apparatus and method for measuring the volume of an object
Applicant: The Regents of the University of California, US
International application number: WO 04/003521
Patients suffering from lymphedema, which causes a person’s arms or legs to swell, could soon find themselves using a laser-based system that measures the volume of their limbs. The patient places their limb into a cylinder, which is then sealed. A reference laser beam is fired through the cylinder and the optical absorption of the beam in ambient air is recorded. The cylinder is then filled with a gas with known light-absorption characteristics. A second beam is fired through the cylinder and a sensor records the light absorption in the gas and ambient air mixture. The ratio of the two absorption measurements is used to calculate a value which is proportional to the gas concentration. In turn, this is proportional to the volume of the object in the cylinder.
• Title: Optical fiber cleaving
Applicant: Tyco Electronics Raychem NV, Belgium
International application number: WO 04/003612
Patent application WO 04/003612 describes a way of cleaving an optical fiber. The first step is to fire a laser at the fiber to form a small slit which runs across the fiber. The second step involves applying tensile and/or compressive forces to the fiber, which causes it to cleave. “The method provides high precision cleaving of fibers and is suitable for use in automated cleaving operations,” say the application’s authors.
• Title: Method for smoothing and polishing surfaces by treating them with energetic radiation
Application: Fraunhofer Gesellschaft zur Förderung der Angewandten Forschung E.V, Germany
International application number: WO 04/003239
Scientists in Germany claim to have invented a fast, inexpensive and automated method for smoothing and polishing surfaces. The idea involves using a laser to melt the surface of a target material in order to remove any unwanted structures. The authors say that continuous wave light or pulses with a duration of greater than 100 microseconds should be used to melt the material’s surface to a depth of approximately 5 to 100 microns.