Rangefinders

© Brooke Clarke 2009

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Background
How They Work
Equipment
    Bushnell Golf Yardage Pro 400 Binoculars
    Laser Technology Criterion
Links

Background

There are many applications for range finders (Wiki) such as: photography (to adjust the lens focus), golf (to determine what club to use), military (adjust weapon for range and target designation), rifle scope graticule (known height) etc.

How They Work

Radar, Sonar & Optical Pulse

These are "time of flight" systems where the round trip propagation time is measured and divided by twice the propagagion velocity.

Optical

The oldest optical system is based on the concept of stadia.  The idea is that you can determine distance by measuring the included angle of an object of known height.
Examples: K&E 76 0000 Alidade, Leitz 115A transit

Another system is based on the "split image" that's made to align by rotating a mirror.  The difference in angle between the two mirrors can be solved based on their seperation into the range.  This is the method used by "rangefinger" cameras and the military rangefinders that look like a drain pipe as well is civilian rangefinders like the hand held
Edscorp Field Range Finder.

Image property range finders are used in modern digital cameras.  One way these work is to look at the image contrase as the lens is set a various focal lengths.  The highest contrast image is deemed to be the best focused.

Time of flight is used in modern digital optical range finders like the Busshnell golf binoculars and the Laser Technology Criterion units.  These typically have one lens for the outgoing pulse of IR light and a seperate lens to focue the light on a fast photo sensor.

Equipment

Bushnell Golf Yardage Pro 400 Binoculars


Bushnell Golf Yardage Pro 400 Binoculars
Bushnell Golf Yardage Pro 400 Binoculars



Laser Technology Criterion

This is the model 400 that includes tree measuring functions.

When in Survey measurement mode and the trigger is pressed you hear a buzzing sound as the laser range finder and other sensors are working.  When aimed at a wall about 4 feet away the spot size as viewed using the PAS-6 IR scope is about an inch high and half an inch wide.

Laser Technology Criterion
Laser Technology Criterion
Laser Technology Criterion





Links

Back to Brooke's Products for Sale, Navigation Orientation & Position, Alidade, Sundials, Surveying, Time & FrequencyMilitary Information, Home page

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