When I point a 5 milliwatts red laser at a pile of barium borate crystals, all I get is red speckles of scattered light. When I point a 100 milliwats blue laser at the same pile of barium borate crystals, I get blue speckles. When I point a 2000 milliwats green laser at the pile of barium borate crystals, I get green speckles. Scientists say barium borate should decrease the frequency of transmitted laser light by 50%. How come spontaneous parametric down conversion I do not observe? Whether I use a single crystal or more, I get the same result. Speckles of scattered light of the same colour.