1. Introduction

Every now and then, a scientific breakthrough occurs that has a revolutionary impact on daily life. One example of this is the invention of a system for light amplification by stimulated emission of radiation. Few people realized at the time of its invention that it would prove to be such a useful (and lucrative) device, but it ultimately launched a new scientific field and opened the door to what is today a multi-billion dollar industry. Today, the system is ubiquitous in the commercial marketplace, used in CD players, corrective eye surgery, tattoo removal, industrial assembly lines, supermarket scanners, optical communications, and optical data storage. The system is well known under its abbreviated name. Do you know this abbreviated term? If not, continue to read the following paragraph copied from https://www.aps.org/publications/apsnews/200312/history.cfm to get some hints.

The principle of the device dates back to 1917, when Albert Einstein first described the theory of stimulated emission, but the practical device has its roots in the 1940s and early 1950s, particularly in the work on microwave spectroscopy – a powerful tool for discovering the characteristics of a wide variety of molecules – by physicists Charles Townes and Arthur Schawlow. Townes realized that the wavelengths of infrared and optical light, because they were shorter, would be powerful tools for spectroscopy. Schawlow came up with the idea of arranging a set of mirrors, one on each end of the device's cavity, to bounce the light back and forth, thus eliminating the amplification of any beams bouncing in other directions. Eight months later, the two men wrote a paper on the proof of concept for their work, published in the December 1958 issue of the Physical Review (Vol. 112, No. 6, pp. 1940-1949), and received a patent for the invention of the system two years later. Still, while Townes and Schawlow are the names most often associated with the invention because of their 1958 paper and subsequent patent, numerous others made vital contributions. Perhaps that is why the question of who really invented the system has proven to be a fairly litigious one. (…)

Now, you should know that the text talks about a laser. This device will provide context in this Unit through which you will practise describing the working principle of a device and its functions, which is a vital skill for a future professional engineer. In addition, you are going to learn and use some useful presentation phrases used to make your explanations as clear as possible.

 

Contents:

Unit 1c revises and introduces some grammar points and signposting phrases used to give a presentation to describe how a system or machine works:

  • Describing how something works using the Present Simple tense
  • Describing functions of a device: to be used to/for/in/during
  • Collocations (= set expressions), for example, a laser beam, a field magnet
  • Presentation phrases, for example: Let´s move on to the next section. Now, I am going to hand over to…