New Melles Griot Inc. Helium-Neon Laser Tubes.
 100’s of tubes available from stock. Quantities may be limited.
 
• Over 30 years of experience with helium-neon lasers.
• All tubes emit a Gaussian TEM00 beam unless otherwise noted.
• Power supplies and ballast resistors also available.
• Available quantities vary from 1 piece to 300 pieces depending on the model.
• Typical lifespan of a Melles Griot He-Ne laser tube is 20,000 hours of operation.
• We provide a 180 day limited warranty.

Also Available:
05-LHP-503
05-LYR-006: multi-mode, 0.1mW min.
05-LHP-064
05-LHR-178
05-LHP-156
05-LGR-332
05-LHR-302
05-LHR-079
05-LHR-200
and more...

632.8 nm (commonly referred to as 633nm) red laser tubes:

543.5 nm green He-Ne laser tubes:

HeNe laser tubes are ideal for:
• Holography
• Raman spectroscopy
• Low level laser therapy
• Test and measurement
• Physics demonstrations for classrooms and science fair projects.

Helium-Neon gas lasers require a ballast resistor in order to operate properly.  HeNe laser heads have the ballast resistor built-in to the cylindrical metal enclosure; however bare glass HeNe tubes need one to be provided.

Wire wound resistors are the most reliable, and therefore the best choice for use as a ballast. Carbon composition resistors are a fine choice for lower current requirements, such as 4.5mA and below. These are getting hard to find in the necessary 2 Watt power.  Carbon film and metal film resistors are definitely not recommended. They have a tendency to degrade due to the high transient currents inherent to the laser starting process.

Selecting the proper ballast resistor based on wattage is very important. To prevent the least expensive component in the laser system from becoming the weakest link, it is recommend to choose a resistor wattage that exceeds the formula P=I²R by 10% or more. This component will be exposed to a high temperature environment and high voltage pulses during starting which can place it under constant stress. When connecting the ballast to the tube, it is important to insulate it properly. There is usually greater than 10,000VDC between the ballast and ground during the start-up of the tube.

Most tube manufacturers recommend mounting the ballast resistor less than three inches from the anode. This reduces stray capacitance between the anode and cathode. The stray capacitance is a physical phenomenon, parasitic in nature, and results from a capacitance that is created by the anode acting as one plate, air acting as the dielectric and ground acting as a second plate.

The connection between the anode and ballast can be one of the most critical in any laser system. A HeNe laser tube acts as a negative resistive load. As the current increases through the load, the voltage drop decreases. This negative resistance is typically 40K to 50K ohms. In order for the power supply to see a normal load, it is necessary for the ballast resistance when added to the negative resistance of the tube, have a net positive resistance of approximately 25k ohms or more. This net positive resistance may have to be increased to reduce the effects of the stray capacitance on the anode of the tube. As the stray capacitance increases, three things happen. The anode draws current from the power supply. It reduces the voltage drop on the tube, and it reduces the impedance at the anode. These three factors create a relaxation oscillator. When this happens it causes the ionized gases to extinguish. At that time the power supply sees no load, applies a high voltage to ionize the gases again and starts the cycle over.

Choosing the correct ballast resistor is an important  step in making your laser work propery. Use the value of resistor that is recommended. We offer a variety of 5 Watt wire-wound resistor values to meet the needs of most HeNe lasers under 15mW.

REQUIRED BALLAST RESISTOR:

68K Ohm, 5Watt

75K Ohm, 5Watt

82K Ohm, 5Watt

100K Ohm, 5Watt

Wire-Wound
Ballast Resistors
$3.00 each

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