FAMOS aims to make OCT light sources more compact

Ashley N. Rice, ashley.rice@photonics.com

Optical coherence tomography light sources will shrink to one-fifth the size of conventional devices with the help of a tapered laser being developed by the European Union project FAMOS (Functional Anatomical Molecular Optical Screening).

Seventeen partners have joined forces to bring OCT – a key technology displaying structures located a few millimeters inside tissue – to the forefront. OCT requires white laser light that emerges when a special glass fiber is irradiated with a femtosecond laser. As these lasers generate heat, they must be water-cooled, making the equipment bulky and difficult to transport.

The FAMOS project will develop a tapered laser combining excellent beam quality with very high output power that will serve as a pump source for OCT light sources.

FAMOS – a four-year project begun in October 2012 and composed of laser and medical technology manufacturers and of scientists from universities in Vienna and St. Andrews (Scotland), London University College, Weizmann Institute (Israel), Technical University of Denmark and Ferdinand Braun Institute (Germany) – will address these issues to develop a smaller, more compact light source.

Positron emission tomography, magnetic resonance imaging and CT scans are the diagnostic standard today for diseases that require sophisticated imaging methods while taking biopsies. Laser methods could become the techniques of choice, particularly for examing skin, the retina and the intestine, if the devices were portable and cost-efficient.

Ti:sapphire lasers can be stimulated at wavelengths around 500 nm, but until now, mostly water-cooled solid-state lasers with an emission wavelength of 532 nm have been used.

Within the ridge waveguide, high-quality radiation is generated, which is amplified within the tapered section – resulting in excellent beam quality with very high output power.

“Our task at FBH is to develop a [10 W] semiconductor laser with very high beam quality [at 1030 nm],” said Bernd Sumpf, head of the FAMOS project at FBH. “Colleagues from Denmark will then frequency-double the light, thus bisecting the wavelength [to 515 nm].”

The laser will be used by a Vienna-based industrial partner to pump a femtosecond Ti:sapphire laser, which will excite the white-light OCT source. If this works, only ambient air will be needed for cooling – requiring only a tiny fan. This will potentially shrink the equipment to one-fifth the size of current devices.