SURFACE PLASMON RESONANCE SENSORS AND METHODS OF OPERATION

摘要

A biosensor comprises a scanner (3) for applying a scan angle to a light beam and also for applying a high frequency oscillation or dither centred on the scan angle. The scannable oscillating beam is directed to a surface plasmon resonance interface (8) whence light is reflected to a photodetector (10). If the scan angle departs from the resonance angle, the reflected light has a component at the dither frequency. The detector detects this component and derives from it an error signal (5) which is fed back to control the scanner (3) to cause the scan angle to track the resonance angle. A further embodiment applies a high frequency variation in wavelength, the scan angle being fixed.