12 Feb 2003
The pick of this week's patent applications, including a VCSEL with improved light output.
• Title: Instruments and methods for examining and quantifying cataracts
Applicant: Visual Pathways, US
International application number: WO 03/009745
A US company has come up with a way to determine the extent to which a cataract impairs vision. The method involves illuminating the retina with light, which is then either reflected back through the lens or scattered by the cataract. The inventors say that the amount of scattered light can be used to quantify the extent to which the cataract impairs the eye's vision.
• Title: Vertical-cavity surface emitting laser having improved light output function
Applicant: Luxnet Corporation, US
International application number: WO 03/010864
The application describes a light guiding structure that improves the light-output-versus-current curve of a VCSEL by altering the spatial modes. The device comprises a bottom mirror, a light emitting layer and a top mirror constructed from layers of a semiconductor material. Adjacent mirror layers have different indices of refraction. "One or more of the top mirror layers is altered to provide an aperture defining layer that alters the spatial mode of the device," claim the authors.
• Title: Semiconductor light emitting device comprising uneven substrate
Applicant: Nichia Corporation, Japan
International application number: WO 03/010831
Nichia is patenting an LED that has an uneven substrate. The company says the uneven substrate helps scatter or diffract the light generated in the light-emitting region. The recesses in the substrate are also said to stop crystal defects forming in the semiconductor layers.
• Title: Method of cutting material for use in implantable medical device
Applicant: 3F Therapeutics, US
International application number: WO 03/009785
Patent application WO 03/009785 describes a laser-based system that cuts material into segments for use in implantable medical devices. The system combines a laser and a stepper, which are controlled by a computer. According to the patent, the laser power is selected both to melt the cut edges and prevent fraying but also to minimize heat transfer through the rest of the segment.
Jacqueline Hewett is news reporter on Optics.org and Opto & Laser Europe magazine.