  The parametric fluorescence from a nonlinear crystal forms a conical
radiation pattern. We measure the angular and spectral distributions of
parametric fluorescence in a beta-barium borate crystal pumped by a 405-nm
diode laser employing angle-resolved imaging spectroscopy. The experimental
angle-resolved spectra and the generation efficiency of parametric down
conversion are compared with a plane-wave theoretical analysis. The parametric
fluorescence is used as a broadband light source for the calibration of the
instrument spectral response function in the wavelength range from 450 to 1000
nm.
