Helium cadmium laser: Dangerous for humans.
You should not get in the way of their beam. Helium cadmium lasers are categorised as laser safety class 3B which means: contact with eyes and skin is not recommended.
In short: Working with this laser requires appropriate protective measures. In principle, this laser is a completely tight tube filled with a helium cadmium gas. This tube works in the blue and ultraviolet spectral range.
It can generate two wavelengths which are measured in newton metres: 325 and 442. The 325 line is not visible to the human eye, but leaves a blue spot on many materials. This is due to fluorescence.
Helium cadmium lasers are generally not used commercially. They are simply too expensive and the service life is far too short for the price. Experts assume 10,000 operating hours. They can be found in cancer prevention and they can be used for generating holograms.