Laser ride-height sensor on the Ferraris
The Autosport.com gallery for Saturday of the Malayisan Gran Prix contains a number of photos of the front chassis bulkheads of cars. The things you normally see on the front bulkhead of a Formula 1 chassis are: the ends of the torsion bars (they take the place of the suspension springs on F1 cars), the steering rack, the brake fluid reservoirs, and maybe a random electronic unit.
This photo of the Ferrari chassis has all those things but what's interesting me is the sticker on the front of the electronics unit that reads "Optimess". The real tip-off though is the international warning symbol for laser radiation. That unit is laser ride-height sensor. It works, as far as I know, by shining a laser on the road surface through a small hole in the bottom of the nosecone. The beam is directed not exactly straight down, but at a small angle such that reflected light would not come back at the laser diode, but at an array sensor next to it in the package. The sensor array is like the sensor in a camera, but tuned to the wavelength of the laser. As the distance from the groud of the sensor package changes, the spot of reflected light moves on the sensor array due to the triangular shape created by that small angle I mentioned earlier.
Such ride-height sensors are frequently used by Formula 1 teams in test sessions, but I've never seen one fitted on a race weekend before. Teams use lots of different sensors and data recording equipment in test sessions but discard it for race weekends due to the extra weight and holes required in the bodywork etc. It is especially odd that such a sensor package would be used in Malaysia since all the teams except Spyker tested there the week before.
Ride-height sensors are used on race cars to get a better idea of how the aerodynamic performace of the car relates to height off the road surface and it's attitude on the road (there would be a sensor at the back as well). There are positional sensors on the suspension as well, but these cannot tell you the exact height of the car off the road because they don't take account of tyre deflection. Another use for the ride-height sensor is to use that data in conjuction with the suspension data to determine tyre deflections. This secondary use is more common on sportscars however as in a formula car there is really only room for one sensor in the centre of the car at either end and thus it can't take account of body roll and thus get a good picture of what the tyres on either side of it are doing. On a sportscar you can position a laser sensor very close to each wheel.