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Characteristics of a HeNe Laser IV

The helium neon laser is a gas laser that was first developed in the 1960s to observe the energy exchange between helium and neon electrons. HeNe lasers are now used for holography and have generally been displaced by diode lasers for most applications, claims the University of New South Wales.

Components
- All lasers are made up of three main components: a resonator, active medium in the resonator (in this case neon) and an energy source for the active medium (in this case helium). The resonator in an HeNe is a glass tube that is filled with helium to a pressure of roughly 1 torr and neon gas to a pressure of roughly 0.1 torr. A single torr is the pressure equivalent to 1/760 of an atmosphere. The helium acts as a continuous energy reservoir for the neon while it's excited, which is why there's more helium in the glass tube than neon.
Laser Type
- Gas lasers come in one of three types: neutral atom, ion and molecular. An HeNe laser is a neutral atom laser. Neutral atom lasers emit visible radiation, operate in a continuous wave, are highly collimated, very inexpensive to construct and safe to use. The HeNe laser was the very first gas laser and, as a result, the first neutral atom laser, suggests the UNSW. It was invented by Ali Javan and colleagues in the early 1960s.
Neon Excitation
- Most scientists agree that this laser should actually be called the neon laser because only the neon is excited, according to the University of Bergen. Neon is excited when a high voltage DC current is introduced to the gas at 10 kilo volts. The high voltage current is only applied for a short time to ionize the gas, after which the voltage is lowered to 2 to 4 kilo volts. The electrons in the neon jump into the next state and emit light. Helium keeps the neon gas excited by providing it with energy by transmitting electrons to it.
Laser Beam Stability
- The laser beam in a HeNe laser is perfectly stable. It flows in a continuous wave because the helium gas captures burned off neon electrons and passes them back into the neon when the two gases collide to keep the wave moving. In other words, the neon wants to keep its electrons but can't because they're moving too fast; the helium is forced to take the electrons but doesn't want to keep them, so gives them back to the helium when the opportunity presents itself. As long as an electric current is provided and the gas doesn't escape, the neon wave or light will burn indefinitely.

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