Speed of Light Apparatus

Features

• All solid-state transmitter/receiver design
• Low-voltage electronics operation
• Fiber optic delay requires no optical alignment
• Safe, visible LED light source
• Quick set-up and measurement
• Impact-resistant, protective enclosure
• Rubber feet on chassis bottom for adhesion on smooth surfaces
• Contained light beam is ideal for small areas
• 28-page full-color manual with step-by-step assembly, operation instructions and sample oscilloscope displays

(The apparatus consists of an electronics circuit board in protective plastic enclosure, two fiber optic cables, test connections for all outputs and a 110Vac-to-dc power adapter. The optical fibers terminate in simple cinch-collet connectors for easy assembly and efficient coupling. A 20MHz oscilloscope is required.) Adapters for 220Vac will be furnished upon request.

IF-SL-K: Kit Version
IF-SL-A: Assembled Version

With Industrial Fiber Optics' Speed of Light Apparatus, measuring the speed of light is now easy and quite accurate. Such was not the case for many centuries. The famed Galileo--after he attempted to measure the speed of light with an unlikely arrangement of lanterns and flags on tall towers--decided that light must travel at infinite speed. Later, Armande Fizeau used an elaborate mechanism with mirrors, lens and huge rotating cogwheel to determine if the speed of light was, in fact, not infinite. He got close. After many years we now know light does not travel at infinite speed, but rather 299,792.4562 meters per second in a vacuum.

With the proper combination of electronics, electro-optics and fiber optics this once-difficult measurement is simple and can be conducted in any lab or classroom. All that's needed is a 60 x 100cm table, 110Vac electrical power, oscilloscope and the Speed of Light Apparatus.

To conduct this experiment, first apply 110Vac power to the oscilloscope and Speed of Light Apparatus, then connect oscilloscope probes to apparatus test points. After calibration, the oscilloscope monitors the reference and delayed pulses, the time delay is measured and the speed of light calculated.

A typical oscilloscope display depicts the reference signal and the delayed optical signal through optical fiber (100 ns of delay through 20 meters of optical fiber).