A custom CMOS camera for sensitive SPR measurement

We have created a custom CMOS camera with 256x256 pixels, each with four channels, suitable for use in SPR experiments. The optical input to the experiment is modulated and we lock-in to the modulation frequency with our camera by taking four separate images, with each exposure lasting one quarter of the modulation period. The amplitude and phase of the signal can be reconstructed using these four measurements. In an SPR experiment, using modulation allows very sensitive measurements without needing moving parts for angle scanning for example. Also, modulating the optical input improves the performance of the camera by moving the signal of interest away from low-frequency noise sources such as vibration, thermal drift and 1/f noise. Our camera has increased well depth compared to standard cameras, of approximately 1.2Me" per channel which results in improved signal to shot noise ratio.