Optical resonance analysis unit

An array surface plasmon resonance (SPR) analysis instrument comprising:

• (a) a reflective SPR sensor array;
• (b) a light source assembly arranged to project a collimated beam of light onto the reflective SPR sensor array to provide a reflected array image of the sensor array, and to scan the incident angle of the collimated beam of light over an angular range;
• (c) a detector assembly oriented to receive the reflected array image of the reflector SPR sensor array over the angular range, the detector assembly comprises a two-dimensional detector sensing element that is tilted with respect to the optical axis of the lens assembly in accordance with the Scheimpflug condition, and a lens assembly for focusing the reflected array image of said reflector SPR sensor array onto said tilted two-dimensional detector sensing element, and
• wherein said lens assembly comprises an objective section which is arranged to produce a virtual image of the tilted reflected array at infinity, followed by an imaging section arranged to transform the virtual image of the tilted reflected array into a real tilted image on the tilted detector sensing element.