6A01.05 - Speed of Light - Laser Diode

See paragraph one in the procedure section.
See paragraph two in the procedure section.
Code Number:
Demo Title:
Speed of Light - Laser Diode
Speed of Light
Area of Study:
Optics, Astronomy
Laser Diode pulser unit, corner cube, digital oscilloscope, laptop with Softscope interface, optics rail, meter tape measure, Plexiglas block.

Align the pulser unit and the corner cube when they are separated by a distance of 1.25 meters ( total path = 2.5 m ).  Either the digital scope or the laptop with interface can be used depending on what type of projection you want to do.  The digital scope usually has less noise when the corner cube is moved.  You will get a single rise curve for a single path and a double rise curve for the two paths.  The part of the curve to measure is the first full rise (time of the sent pulse and its return from the corner cube).  Both the digital scope and the laptop have cursers that can measure directly the time for that distance traveled.  

An interesting experiment to try is the measurement of the index of refraction of another medium such as Plexiglas.  Place the Plexiglas block into the light path and measure the change in the path time difference between the air and the Plexiglas.

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