Mythbusters: Velocity Measurement thing

[Stiganator]

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[PottedMeat]

You mean the thing that looks like a piece of pie? My guess is that the arc part is a reflector and at the base is a infrared or laser emitter. Object breaks beam, controller starts timer, controller waits for object at other pair of sensors, timer stopped? They use a pair of these things right?

 

[Stiganator]

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[BrownTown]

I'm pretty sure it uses a laser beam and waits till the beam is broken.

 

[PottedMeat]

Ah found it: http://www.competitionelectron...Prochrono_Digital.html

The manual says its a electromechanical diffuse light sensing system. I think those arcs are ambient light diffusers - it doesn't use any emitters. It's probably some very narrow angle daylight sensor. I wonder where the 'mechanical' part comes in, some sort of MEMS sensor probably isn't necessary.

 

[Stiganator]

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[BladeVenom]

There are also radar chronographs available for paintball and other sports.

 

[firewolfsm]

photogate, my teacher used them in physics.

 

[ScottMac]

Originally posted by: Stiganator
yeah there is a pair, but it doesn't look like it operates optically. It just looked like two metal antennae.

The "antennas" are supports for a plain white background. You don't need the background for most testing. Without the background, they give you a specific arc of coverage, and an indication of valid distance above the chrono's sensor.

That's just a standard shooter's chronograph ... good ones are a couple hundred dollars.

 

[l0cke]

If you want to go cheap, you can sometimes pick up a Chrony F1 shooting chronograph on ebay for around $50