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Highlights from Opto and Laser Europe, July 2000

June 23, 2000

Consultants and suppliers question train signal claims

Claims made by the UK's rail operator Railtrack that its signal lights conform to the International Commission on Illumination's (CIE) recommendations have been questioned by its signal suppliers and external technical consultants. The allegations follow a story in last month's issue (OLE June p5) which claimed that Railtrack has not acted on a recommendation by the CIE to shift the colour of its yellow signals further towards the yellow part of the spectrum and away from the red. It is believed that the change will help avert train accidents by avoiding confusion between red and yellow signals. Railtrack claims that its signals, which are based on a British standard BS:1376, already comply with CIE standards. But the sole supplier of signal lenses to Railtrack has told OLE that Railtrack's claims only apply to certain elements of the signal.

Fraunhofer Institute spins off diode laser company

Researchers from the Fraunhofer Institute in Jena, Germany, have set up a spin-off company to develop miniature high power diode laser systems based on wide stripe laser diodes. Called Unique Mode, the company claims its lasers will have much greater power and a larger depth of focus compared to conventional diode laser systems.

UK ophthalmologist urges for more research into laser eye surgery

A leading ophthalmologist in the UK has said that more research is needed to determine whether laser-assisted in-situ keratomileusis (LASIK) is completely safe. Professor John Marshall, of St Thomas's Hospital in London, UK, is concerned that long-term follow-up studies of the LASIK technique have not yet been possible, and that patients should be made more aware of the potential risks involved with laser eye surgery.

Why do butterflies have iridescent wings?

The spectacular iridescence of butterfly wings has captivated many a scientist. Over 70 years ago, the bright colour of particular species' wings was attributed to thin-film interference effects rather than pigmentation. Recently two schools of thought on the role of the iridescent wings to the butterflies themselves have emerged. First, it was claimed that they acted as solar collectors. Now, the latest theory suggests that the opposite may be true, and that the wings actually act as sun blocks.

Institute of Physics