Blue-rays would have been either done by telecine https://www.ebay.co.uk/itm/283479247780 (From what I recall its nominally a real time machine). That used flourecent light sources (although I never worked on it, so that could be a lie.)

or by this https://www.filmlight.ltd.uk/products/northlight/overview_nl... a non realtime scanner with "perfect" registration. Again I can't remember the light source, but I suspect its probably an arc gap like large projectors. I do know that it has a massive cooling chamber to make sure it doesn't heat the film though. That scanner is a non-realtime CCD slit scanner.