Surface plasmon resonance sensing method and sensing system

A SPR sensing system comprising:

• a SPR sensor comprising a SPR supporting sensor surface;
• at least one test light source emitting at least one test light beam for illuminating the sensor surface under conditions selected so as to excite SPR at the sensor surface,
• a photosensor to measure a light property of said at least one test light beam as transmitted or as reflected by the sensor surface so as to monitor a condition of resonance at the sensor surface,
• at least one reference light source emitting at least one reference light beam for illuminating the sample under conditions selected so as not to excite surface plasmon resonance at said sensor surface, wherein said photosensor is also adapted to monitor an intensity of at least one reference light beam as transmitted or as reflected by said sensor surface;
• and
• processor means configured to determine a least one property of said reflected or transmitted test light beam taking into account the sensed intensity of the reflected or transmitted reference light beam.