Patent ID: 7879619

Claim:
A surface plasmon resonance apparatus for detecting a substance comprising: a metallic layer comprising first and second metallic regions; a dielectric body adjacent to the metallic layer; a light projection system to project a light beam through the dielectric body and onto the metallic layer to create a surface plasmon resonance at an interface between the metallic layer and the substance; a beam reflector; a beam splitter; and a light detection system comprising at least two light beam sensors to detect a reflection of the light beam from the metallic layer; wherein: the reflection of the light beam comprises: a first light beam portion reflected off the first metallic region; and a second light beam portion reflected off the second metallic region; a first light beam sensor of the at least two light beam sensors comprises a first position sensitive photodetector; a second light beam sensor of the at least two light beam sensors comprises a second position sensitive photodetector; the beam reflector is configured to reflect the reflection of the light beam from the metallic layer towards the beam splitter; the beam splitter is configured to: direct the first light beam portion from the beam reflector towards the first light beam sensor; and direct the second light beam portion from the beam reflector towards the second light beam sensor; the first light beam sensor is configured to: receive the first light beam portion of the reflection of the light beam at the first position sensitive photodetector; and continuously detect a change in an intensity distribution of the first light beam portion along a length of the first position sensitive photodetector to generate a first surface plasmon resonance signal; and the second light beam sensor is configured to: receive the second light beam portion of the reflection of the light beam at the second position sensitive photodetector; and continuously detect a change in an intensity distribution of the second light beam portion along a length of the second position sensitive photodetector to generate a second surface plasmon resonance signal.