Diamond polycrystalline films have been synthesised using the Chemical Vapour Deposition (CVD) technique in order to fabricate new types of photo-detectors for novel photon source characterisation. We present here diamond-based new devices for a range of applications, including (i) VUV spectral output monitoring down to 125 nm, with high selectivity with respect to UV. These devices exhibit a VUV to UV sensitivity ratio above 400, thus demonstrating their solar blindness. Another aspect (ii) addresses the design of intensity or beam position monitors (resolution < 2 mu m) for extremely low wavelengths as encountered in synchrotron light source experiments. These detectors enable in-line beam characterisation with low cross-section. Further, (iii) since diamond exhibits a low carrier lifetime (much less than 1 ns), detectors have been fabricated for the temporal characterisation of ultra-fast (< 100 ps) laser pulse duration monitoring. They can be used for the characterisation of short laser pulses as well as for synchrotron machine diagnostics.