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Here we introduce some properties of light and give examples of our typical system products listed in this catalog using detection technology.

•Young's experiment on interference

Wave Nature of Light

Light has the properties of a wave.

Light can be considered a type of electromagnetic wave like radio waves. These waves act just like the ripples you see on the water surface when you throw a stone in a pond.

The properties of this light "wave" can be shown in a test with Young's experiment on interference. In this experiment, light from a light source is shown on a screen after passing through the slits of 2 plates. The first plate has 1 slit for light to pass through and the second plate has 2 slits. The light coming out of the second plate with the 2 slits appears on the screen as a fringe pattern (stripe pattern). This pattern is caused by interference (waves boosting or weakening each other) with the wave property of light.

Light source

Slit plate 1

- J

•Sound signals

Particle Nature of Light

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Light has the properties of a particle.

The intensity of light varies according to the number of particles. Bright light has many particles while darker light has few particles. Sound and light signals are compared in the figure on the right.

When the strength (amplitude) of a sound signal (seen on an oscilloscope) gradually weakens, the signal gets smaller and smaller and finally disappears. When the light signal on the other hand gradually weakens, the total signal quantity decreases but can still be detected as a few, discrete pulse signals. This is because one pulse is detected as one light particle. These particles of light are called "photons".

▲When sound signals become weak, they can no longer be detected. (Tuning fork resonance test)

•Light signals

▲Light signals can be detected as pulses (particles) even after becoming very weak (very dark).

•Light can circle the earth 7.5 times in one second

—I —I —I I

ity of Light

Light travels at a speed of 300,000 km per second.

The speed of light is so fast it can travel 7 and a half times around earth in one second. This high speed is being put to work in diverse applications such as optical communications for sending large quantities of data in a short time.

A millisecond is one thousandth of a second, a microsecond is one millionth of a second, a nanosecond is one billionth of a second, and a picosecond is one trillionth of a second.

Even though light can move 7 and a half times around the Earth in one second, in a picosecond it moves only a mere 0.3 millimeters (in a vacuum). It is indispensable to research of optical phenomena occurring in an extremely short period of time in new fields such as physics, chemistry, biology and so on.

•1 picosecond is...

■I...L

Light can move 300,000 kilometers in one second and yet ... 1 picosecond is an extremely short period of time in which light moves a mere 0.3 millimeters.

0.3 mm