This has been asked before, every once in awhile. The answer is: yes, it is possible, but the results aren't very good.
Basically, you take a video capture card/box, hook it up to your laptop. Then, have the capture box sample the video...
I'm assuming you've tried the "BIOS function key" approach to raise your backlight levels, and failed.
Also, look through your BIOS options to see if you have some sort of "when in power X state set backlight to Y"...