06 Apr 2004
The pick of this week’s patent applications including an LED-based system that assists hair growth.
• Title: Headphone type apparatus for assisting hair growth
Applicant: Biotech Inc, Japan
International application number: WO 2004/026400
Shining 600 to 700 nm light on your scalp could help hair grow back, according to the inventors of the device described in application WO 2004/026400. Resembling a set of headphones, the device contains an array of LEDs that irradiates the scalp with an intensity of 1500 to 5000 milli candela. The LEDs are pulsed at a repetition rate of 1 to 1.3 kHz.
• Title: High power semiconductor laser diode and method for making such a diode
Applicant: Bookham Technology plc, UK
International application number: WO 2004/027951
Bookham is trying to a patent a design which it says improves the stability and reduces the degradation seen in high-power laser diodes. Specifically, the authors say that their design suppresses any undesired first and higher order modes in the output of a ridge waveguide diode laser. According to the authors, the secret is to use specifically-shaped complex index guiding (CIG) elements. These contain a layer which absorbs the undesired modes and an insulating layer as a first contact to the semiconductor.
• Title: Semiconductor crystal of group III-V compound
Applicant: Mitsubishi Chemical Corporation, Japan
International application number: WO 2004/027126
A carbon-doped III-V crystal is the subject of patent application WO 2004/027126. The crystal should have a carbon concentration of 1 x 1016cm-3 or greater and an oxygen concentration of 1 x 1018cm-3 or less. The authors claim that a semiconductor laser using such a crystal has excellent high-speed modulation characteristics.
• Title: Railway obstacle detection system and method
Applicant: Rosemount Aerospace Inc, US
International application number: WO 2004/026660
A US firm is trying to patent a system which it says detects objects on a railway track and determines if they are a threat to the train. The instrument scans a laser beam over the track in a predetermined pattern and a detector gathers the reflections. The system works out where on the track the reflections have come from and produces an image of the scene ahead of the train.
Jacqueline Hewett is technology editor on Optics.org and Opto & Laser Europe magazine.
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