SRM is the grandaddy of the power-meter market, and even makes (or made) special power meters for researchers with additional sensors. They also make
this thing, specifically for labs.
There are a number of power meters that will show your power continuously through the pedal stroke, and I am surprised to learn that the Quarq doesn't do that. DC Rainmaker is the go-to guy for cycling gadget reviews, and he has a bunch of
power-meter reviews. It looks like the industry jargon for high-frequency power monitoring is "cycling dynamics."