Skip this section if you don't want to hear my dramatic soliloquy about lasers and lightbulbs
Lasers have captivated people's imaginations for years, in fact, 2010 marked the 50th anniversary of invention of the laser (way to go laser!). Since then, lasers have blossomed into a industry of both entertainment and science, and generated countless new innovations across the world. I'd only crossed paths with the occasion laser pointer before I started my engineering career (...and of course I unkowningly used them in things like DVD players, but that doesn't really count...). However, it wasn't long before I was able to understand why lasers represented something much more than just a replacement to a pointing-stick.
For me, it wasn't until I grasped the concept of etendue
and semiconductor manufacturing that I could really appreciate, not only the potential of the laser, but why it will remain an everlasting tool for generations to come. So first let me briefly the concept of etendue.
Etendue is a funny little french word which translates to something like "extended" or "expansive." However it describes a very fundamental idea; something along the lines of how light spreads out from its source and illuminates over a volume, (...that's the wikipedia
definition, anyway) but the the idea of etendue is much simpler to understand.
Let's imagine back around 1880, Edison tucked away in his lab testing filaments for his light bulb, each filament he tested glows hotly as electricity completes its circuit. The soft warm light being generated from his small filament is at the time a very profound way to generate light but if you think about it... it's quite crude... (warning: exaggeration ahead) it's equivalent to popping a balloon to create a breeze or using a stick of dynamite to dig a hole.. sure that's one way to do it but it makes a mess, light goes everywhere, you're covered in light and there's no way to clean it up! (...etendue is basically the optical equivalent to the second law of thermodynamics... you can't create more energy than you put into the system, so even if you add mirrors and lens the etendue can never be decreased... its invariant!)
So let's change the scenario, now we've got a laser and we can picture it buzzing out a little hole and shooting across space as a pencil thin beam of light. It's certainly very clean looking, but what did we change? Well we did a couple things, in simple terms: 1) we made all the light a single wavelength/color and 2) decreased the etendue of the light by many, many orders of magnitude,(...we're talking lots of zeroes here folks), the light has high optical power, emitted from a small source, and well defined in angle. We have rays of light playing together in harmony, synchronized and smooth, rather than a dissonant collection of rays blasting out notes of dissonant frequencies in all directions.
With a laser we've basically captured the genie the in bottle; a way to make light in a pure form, a perfectly smooth undulating wave of light whose collection of rays travel in one direction in perfect synchronization. This means a laser is more or less light distilled into its basic element and packaged to make it easily controlled and distributed; it's Henry Ford's assembly line mixed with the 1's and 0's in a microprocessor... so this is where the semiconductor manufacturing comes in.
Semiconductor manufacturing has created a world built on silicon. The particularly amazing aspect (and there are many) about semiconductor manufacturing processing is its unique ability to scale production and manufacturing. This is what differentiates the laser from the light bulb. The laser is the computer chip of the lighting world (with its little brother the LED). Lasers can be manufactured in ways that rival the best cellphone camera, microprocessor or accelerometer. Semiconductor manufacturing is a batch processing technique so individual lasers can be assembled quickly and inexpensively in much the same way millions of microchips are built each year. Vacuum tubes died with the advent of the transistor and so too shall the light bulb.
So this is why the laser (and we are already seeing it with LEDs) will emerge as the new standard in for illumination. Lasers to the future!