Chapter 10 Notes

Chapter 10 focusses on the two most common UV lasers: the nitrogen and the excimer. Both lasers use similar technologies and in most cases are interchangeable - for example an excimer laser can operate as a nitrogen laser with only a change in the gas mixture employed.

We begin our analysis with the nitrogen laser. There are two types of nitrogen lasers based on the pressures employed. Low-pressure lasers use pure nitrogen as at a pressure between 25 and 60 torr. At these pressures the lifetime of the upper lasing level is about 15ns - the electrical system for such a laser must logically be designed to discharge within this time frame. Although short (relatively speaking compared to most pulsed lasers), design of such a laser is not difficult assuming attention is paid to inductance of the components used - for example discharge paths are usually wide strips of copper and capacitor dielectrics must be designed to have low inductance as well.

A look at a homebuilt nitrogen laser from the Homebuilt lasers site (opens in a new window) showing details of construction of such a laser as well as selection of components

The second type of nitrogen laser is the TEA type as discussed in chapter 10. Although similar in structure to the low-pressure type the nature of this laser's design is much more critical since the lifetime of the upper-lasing level is inversely proportional to pressure. At 760 torr the lifetime is only 2.5ns making the design of an ultra-fast discharge circuit much more important.

A look at a homebuilt TEA laser from the Homebuilt lasers site (opens in a new window) showing details of construction of such a laser as well as selection of components

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