Two-dimensional wave-vector correlations in spontaneous parametric downconversion explored with an intensified CCD camera

Utilizing a new scheme with a single-photon-sensitive intensified CCD camera and a femtosecond laser, we have measured signal-idler correlations over the full cone of degenerate type I spontaneous parametric down-conversion; thereby establishing wave-vector correlations in two dimensions. We discuss the key features of the camera that are important for its use in twin-photon correlation measurements.