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25 Mar 2003
The pick of this week's patent applications including a method that reveals how diamonds have been colored.
• Title: Examining a diamond
Applicant: Gersan Establishment, Liechtenstein
International application number: WO 03/023382
A new optical technique could shed light on how diamonds have been colored. The method described in application WO 03/023382 can determine whether a blue-to-green diamond has been artificially irradiated or ion-bombarded to change its color.
The technique involves scanning 633 nm light through the stone to induce luminescence between 680 to 800 nm. "A rapid decrease in luminescence with increasing [penetration] depth indicates natural irradiation whilst a more rapid decrease indicates ion bombardment," say the authors.
The same approach can also determine if a diamond is a natural or synthetic doublet by using 325 nm light to excite luminescence between 330 and 450 nm. According to the authors, an abrupt change in luminescence with increasing depth shows that the diamond is a natural or synthetic doublet.
• Title: Apparatus and process for the lateral deflection and separation of flowing particles by a static array of optical tweezers
Applicant: University of Chicago, US
International application number: WO 03/024163
Using optical tweezers to separate particles is the subject of patent application WO 03/024173. The invention relies on an array of optical traps. The spacing between each trap is larger than the size of the particle to be studied. An external force drives the particles across the array. By altering the angle of the array relative to the external force, the authors say the particles can be selectively deflected or separated.
• Title: Color photosensor
Applicant: Lumileds Lighting, US
International application number: WO 03/023340
Application WO 03/023340 describes a device that can sense the color spectrum of incident light. The sensor is divided into four areas, three of which are filtered and output a so-called "sensing current". These areas use a single cyan-, yellow- or magenta-colored filter respectively. The fourth area is a subtracting unit that determines the red, green and blue content of the incident light by analyzing the sensing currents from the filtered areas.
Author
Jacqueline Hewett is news reporter on Optics.org and Opto & Laser Europe magazine.
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