Helium-Neon Laser Kit 3

This is about the lowest cost HeNe laser tube and brick power supply available. It consists of a high quality hard seal 6 inch by 1 inch HeNe laser tube from either Melles Griot or Uniphase. These are essentially identical in all respects and have a divergence of around 1.7 mR, not the high divergence of some barcode scanner tubes. The tube is mounted safely inside a molded plastic housing with ballast resistor and attached to a very compact brick-type power supply that runs on 5 to 7 VDC. Also in the housing are a pair of lenses which adjust the beam divergence and 2 or 3 ~1/2" square first surface mirrors which redirect the beam out the side.

HENELSK3

The laser power supply and laser head are already wired together so that all you need to complete your laser is a suitable DC power source. HENELSK3 consists of one (1) unit similar to what is shown in the top two photos. However, the tube, lenses, and mirror, may be easily removed from the housing and/or remounted in the enclosure of your choice if desired. Cut cable tie(s) (if present), remove four (4) Philips screws, loosen 2 hex setscrews, unsnap plastic housing halves, and everything will fall apart. Don't let the tube fall on the floor! The copper ring attached to the HeNe laser tube anode can be pulled free of the plastic housing by bending it down so it will fit through the thin slot conveniently provided.

DC power can be provided by a battery pack (e.g., 4 D cells), DC wall adapter, or DC power supply. Places like Jameco and MCM Electronics have compatible wall adapters for under $10). Or, if you prefer to build your own power supply, schematics can be found at Adapters for DC HeNe Laser Power Supply Bricks. All parts are readily available.

The low voltage wiring is as follows.

6 VDC version (HENELSK3-6): (See Operating Instructions for HeNe Laser Kit 3 - 6 VDC Version).

CAUTION: Double check polarity before applying power - reverse polarity may destroy the power supply.

CAUTION: If rewiring tube, polarity of high voltage is critical. Laser may appear to work with reverse polarity but will be ruined in a few monutes. Copper ring from ballast resistor must go to anode end of the tube which is the one that has the large glass capillary visible inside and where the laser beam emerges.

WARNING: Voltage across tube may exceed 1,000 V. The current is low so it won't be lethal but you will feel it and might drop the tube! :(

Note: The DC input doesn't have to be terribly well regulated but the peak current used by the power supply especially during starting may result in a flickering output if it isn't adequate. A large electrolytic filter capacitor (e.g., 10,000 uF) across the input may help with a marginal power supply. DO NOT let it continue to flicker as damage may result.

The output of the laser with all optics installed is very slightly *converging*, focusing to a point at a distance of 1-2 meters. However, by remounting the tube using the two lenss, a divergemce from about 1 mR to 15 mR can be achieved. The tube itself has a divergence of 8 mR.