General Electric vacuum tube laser repair

Earliest commercial laser welding application. GE used a soft electron-laser pulse to make contact between failed tungsten/molybdenum wires inside a sealed glass vacuum tube, then a power pulse to weld, saving the tube without breaking the vacuum.

The earliest commercial use of a laser was in the mid-50s. Lasers were only invented in the mid-50s, but it's my understanding that General Electric used to use them this way: back in the mid-50s, people used vacuum tubes in their electronics. We didn't have silicon yet — silicon had been invented as a semiconductor in 1947, but it really hadn't been commercialized. So most power electronics had vacuum tubes, and some of these tubes would cost a couple hundred or $1,000. Back in 1950, that's a lot of money. So they would make these things, seal them in vacuum, and then find out that one of the joints inside had failed. Supposedly General Electric took a research laser — you'd have two tungsten or molybdenum wires inside the clear glass vacuum tube — and they would first hit it with a soft electron laser beam that would just soften the wire so it would make contact with the other wire, then come in with power and weld it back together to make the electrical connection and save the vacuum tube. So lasers were used early on. Electron beams were used early on, within the first five or ten years of their having been developed into high-power devices.

Earliest commercial laser welding application. Used to illustrate that any new heat source gets tried for welding.

When Sir Humphry Davy discovered the electric arc in 1805 or thereabouts, one of the first things he did was try to weld with it. The first commercial application I've ever heard of with a laser was General Electric repairing vacuum tubes in the mid-1950s. The laser had just sort of been invented. Back then they didn't have high-power transistors; they used vacuum tubes. Some of these were very expensive, costing hundreds of dollars apiece in 1955, '56 dollars. Sometimes they'd get a bad weld in those little components and they'd have to break the seal, fix it, and put it back together. With the laser they could go in and hit that little post of tungsten or molybdenum, cause one of them to get soft, and with gravity as their aid they could cause the two to touch one another. Then they'd go in with a higher-power pulse and weld them together without breaking the vacuum seal in the glass, because the lasers would go right through the glass if you had the right kind of laser.