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Speed of Light Apparatus
Do-it-yourself assembly kit for measuring the speed of light with fiber optics

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 a 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, 110 VAC electrical power, oscilloscope and the Speed of Light Apparatus.

NOTE: This kit needs assembly before conducting experiments. Easy-to-follow assembly instructions are included with the kit. Some experience with using an oscilloscope and soldering is suggested for completion.

To conduct the speed of light experiment, first apply 110 VAC 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.

An integral part of the Speed of Light Apparatus is an easily understood full-color, often lighthearted manual. It begins by tracing the early steps of technical pioneers in their quest to understand light. The manual also includes detailed step-by-step set-up and measurement instructions and examples with equations for calculating the speed of light.


  • All solid-state transmitter/receiver design
  • Low-voltage electronics operation
  • Fiber optic delay requires no opitcal 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, operating 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 110 VAC-to-DC power adapter.

Adapters for 220 VAC will be furnished upon request.

The optical fibers terminate in simple cinch-collet connectors for easy assembly and efficient coupling.
  Speed of Light Apparatus

Part Number: IF SLK
Price: $135.00

A 20 MHz oscilloscope is required for completing measurements.

Replacement Parts are available.

Instruction Manual
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