Materials needed:
Small cosmetic mirror
Laser pointer
Good aim

I was recently on a show in Shreveport, LA as a camera op with Matthew as the Gaffer. I had a close up shot that I was picking off and the BG behind the talent was too dark for a daytime scene so Matthew and I were discussing getting light in the corner. We put up a head in an attempt to put a highlight in the BG and we didn’t really care for it. We decided to try to get some spectral highlights off some books but couldn’t for the life of us find where exactly to place the head to get the light to reflect right back into the lens.

Here comes the good part. I had the idea to get a small mirror from the MAU department, similar to one that’s carried inside a purse, and put that on the bookshelf at the exact place I wanted the spectral highlights to be and put the laser pointer on top of the matte box perpendicular to the MB. I then aimed the laser pointer at the mirror and it then reflected off and hit a wall out of the frame (we of course angled the mirror so the laser point ended up hitting out of frame) and put the head right in the beam of the laser and boom, we had perfect spectral highlights.
–of course, this trick is unnecessary if you can find the angle of incidence, but if you are struggling, this is a sure fire way make it happen, quick.–