I never quite got the concept behind Turbinlite. I mean, if you're able to train a huge torch on another aircraft in mid-air, you can train huge guns on it as well, right?
You have got to think about it in terms that this was the very nascent stage of radar development and the early associated use in an airborne sense. The early radar-equipped platforms such as the Bristol Blenheim were used since they had the room for dedicated radar operators and the necessary room for the equipment. However the also lacked the necessary speed advantage over the German Heinkel 111s and Dornier Do 17 bombers then raiding the UK to be truly effective, the Blenheim being able to find the bomber, but often not being fast enough to be able to reach a position in which to shoot it down.
Non-radar equipped single-engined fighters, whilst being fast enough to catch the bombers, simply could not find the bombers to shoot them down. In addition, there was some doubt as to the best way to find, intercept and shoot down attacking bombers at night. The idea put forward was that an aircraft that carried a searchlight could light up the attacking bombers for partner non-radar equipped fighters to shoot them down, since the single-engine fighters would have the performance advantage over the German twin-engine bombers.