Twin HeNe's

On my everlasting quest to have the consummate laser collection, I have dwelled upon the darkest spelunks of the internet to find true treasure. When an excellent deal came up for an 18 inch 2mW green helium neon laser tube, I knew that this would definitely be a worthy investment to the collection. Coincidentally, at this time I spotted a neglected and diminutive .08mW tube of the same type, waiting to be adopted. This poor fellow was a third of the size, and the beam was multi-mode. After weighing my options and consulting my wallet, I decided to adopt both the little HeNe tube and his big brother.

Twin Yellow and Green HeNe lasers!

However, the little 6-inch tube still didn't have a home. I had a portable 6-inch red HeNe built into a transparent plastic enclosure, so I swapped the green into there for some time.

Red HeNe in plastic enclosure.

After some careful thought and planning, I realized that the enclosure was actually large enough for both of the 6" red and green HeNe tubes. I bought another power supply brick, and installed it in the enclosure.

Two HeNe's installed!

Both tubes run off of 880V, which is provided by the copper blocks. The two white 3V lithium "D" batteries provide power to the copper blocks. The red switch activates the red HeNe, and the green switch activates the green HeNe. In order to add to the color fusion combination, I aligned the beams to combine using a dichroic mirror, one which passes green light but reflects red.

View of the green laser passing through the dichroic mirror.

View of the red laser reflecting off of the beam-positioning mirror.

Combined dot from the red and green lasers.

I love the plasma exposure!

Ahh, the nice warmth of the helium neon laser. Even though 543nm green is about four times more visible to the eye than 632nm red, the red HeNe still overpowers the green HeNe in brightness. The one thing interesting about the green HeNe though is that not only is it multi-mode, but it also mode hops! Since movement is not characterized well in pictures, I whipped out the GIF-ation machine and created an animation to convey the effect.

Fantastic!

Grant