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Model 2520 User’s Manual Measurement Considerations F-11
Increasing laser diode pulse measurement speed
Overview
The index of refraction of a given optical media is the ratio of the speed of light in a
vacuum divided by the speed of light through the media. As a ray of light passes through
optical media of differing indices of refraction, reflections and coupling losses will result.
These reflections will act to generate constructive or destructive interference with other
reflections and desired wave fronts. These undesired reflections may strongly affect the
performance of the optics system. Measures must be taken to prevent the effects of
unwanted reflection in an optical system. Optical engineers have developed design
methodologies to identify and control the negative side effects of differing indices of
refraction while capturing the desired optical mechanisms.
Figure F-10 shows an optical pulse propagating through an optical media of differing
indices of refraction. In this example, multiple reflections combine to form a second image
of the pulse trailing behind the first. Preventing the reflections would help maintain the
fidelity of the original pulse shape.
Figure F-10
Optical pulse propagation through differing indices of refraction