School of Physics & Astronomy

Classical and quantum optics

Configuration of magneto-optical trapResearch teams in the School are active in the optics fields in areas ranging from the fundamentals of the interactions between light and atoms, through to the development of new optical instrumentation to fit specific industrial needs. An example of the former is the use of tunable-diode-lasers to slow down (cool) and trap atoms at temperatures close to absolute zero for long periods (see diagram). This then allows these atoms and their interaction with light to be studied closely. Other areas include:

 

  • exploiting quantum interference between different atomic states within the same atom to switch off absorption
  • laser modes with orbital angular momentum
  • the generation and investigation of single-cycle optical pulses.

Static Fourier transform spectrometerAt the more applied end, we show here an example of a novel optical instrument developed at St Andrews. This allows the spectrum of a light source to be measured accurately, robustly and quickly, and with a small, inexpensive instrument. The optical elements, which include polarisers and birefringent crystals, are sandwiched in front of a TV camera. The interference fringes that are produced on the camera are analysed by the computer to determine the spectrum. This system is now being used to detect toxic gases at the parts per million and parts per billion levels.

skin cancer cameraWe have also developed optical systems for use in hospitals.  The system on the left uses a phosphor coated bulb to illuminate skin with deep blue light.  A filtered camera monitors the fluorescence, which may be used to detect skin cancer.  This system was developed in collaboration with physicists at Glasgow and clinicians at Dundee's Ninewells hospital.

Our work in this area of "biophotonics" is expanding, with a wide range of work being carried out in collaboration with clinicians, biologists, and chemists.

Bringing together cutting edge theory and experiment we have teams working in the field of quantum optical information processing. This may open up possibilities of totally secure optical communication systems, based on the fundamental aspects of quantum mechanics.

Other optical and laser instrumentation is being developed for applications in medical imaging, underwater imaging, inspection of surfaces, and micro-manipulation of tiny particles.

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27.7.05