# A gadget I dont know the name of

Pretty embarrassing but thats the truth.

Im very much interested in reading how it actually works, so I guess howstuffworks.com would be a great place to start, but I dont know the name of the device. Neither in English nor in my own language.

Well heres what the device does:
It works with a laser and when pointed to something, it shows how far the object is relative to the device.
I have a pretty good idea how it could work but I would like to read it abit more detailed.

Whats the device called?

fawk3s

turbo
Gold Member
I believe that you are describing a laser ranging device. It might be described as a "laser range finder" if you want to narrow the search a bit.

mgb_phys
Homework Helper
It's simply called a laser rangefinder.
If it has a visible red laser, a large window for the return beam and only works to 10m or so it's probably a phase measuring rangefinder.
These are generically called Disto's - after Leica's original model but you can buy them from dozens of makers.

To clarify previous posters' comments, there are in fact some devices called laser range finders that use lasers for the purpose of measuring distances, but they are rare and expensive. Most devices you find in stores under $100 mark are in fact ultrasonic range finders, and they only use lasers to help you visualize the point where the device is pointed. turbo Gold Member To clarify previous posters' comments, there are in fact some devices called laser range finders that use lasers for the purpose of measuring distances, but they are rare and expensive. Most devices you find in stores under$100 mark are in fact ultrasonic range finders, and they only use lasers to help you visualize the point where the device is pointed.
That's not quite accurate. There are plenty of laser range finders available that are optimized for golf, bow-hunting, etc, and they often sell for \$200 or less. They are compact, portable, and often water-resistant so that they can be used in inclement weather.

rcgldr
Homework Helper
There are also laser sensor devices used to measure short distances very precisely.

mgb_phys
Homework Helper
Three main technologies:
For very close range you use a laser triangulation sensor. It has a visible beam that hits the surface and is reflected back into a 1d ccd-camera, from the position along the sensor and the fixed angle between the outgoing beam and the sensor you can work out the distance by simply trig. It only works at a range of a few cm and needs a reflective surface but is accurate to microns.

At 10-20m, indoors without too much background light you can use phase to measure to a few mm. It takes several seconds to make a measurement. = DISTO

Outdoors at long range you use time of flight. Fire a laser pulse (normally infrared), start a clock, detect the return, stop the clock and use the constant speed of light to get range.
Accuracy is 1m for cheap golf scope, to mm for a survey theodolite. Range is upto earth-moon! You also use these for 3D laser scans, they can go very fast at short range because you can fire another pulse as soon as the last one has returned - 10,000s shots/second.

Pretty embarrassing but thats the truth.

Im very much interested in reading how it actually works, so I guess howstuffworks.com would be a great place to start, but I dont know the name of the device. Neither in English nor in my own language.

Well heres what the device does:
It works with a laser and when pointed to something, it shows how far the object is relative to the device.
I have a pretty good idea how it could work but I would like to read it abit more detailed.

Whats the device called?