Wednesday, 18 February 2015

Dr. Evil: When I ask for sharks with frickin' laser beams on their heads, I expect sharks with frickin' laser beams on their heads!

Dr Evil making demands in Austin Powers International Man of Mystery.
You can buy shark laser pointers online.

Newly acquired in our Jewellery Workshop  - A Laser Welder - not attached to a sharks head but positioned on a workbench.
The word laser started as an acronym for "Light Amplification by Stimulated Emission of Radiation" Amazingly the concept was first proposed in 1917 by Albert Einstein but didn't became a reality until 1960. You can read here about the history of Lasers, its not clear cut who the actual inventor is but Theodore Maiman made the first laser operate on 16 May 1960 at the Hughes Research Laboratory in California.
A Jewellery Laser Welder uses light energy that produces heat to weld metals. The heat from the welder is finely focussed in a narrow beam, so that the surrounding area is not effected or discoloured by the process. Argon gas is used to shield the surrounding area and reduce oxidation and if Laser filler is used make that flow smoother. This makes lasers particularly useful for:
  • Repairing damaged jewellery without the need to unset and then reset heat sensitive stones. 
  • Pieces can be repaired with only localised heating preserving the appearance of the item.
  • Rejoining areas that are particularly hard to get to.
  • Ring resizing.
  • Retipping and repairing claws.
  • Repairing costume jewellery.
  • Repairing filigree pieces.
  • Repairing items that contain epoxy resin, enamel or pearls.
Can be used on platinum, palladium, gold, silver, titanium and other jewellery metals.

Our new Laser Welder in action

Read on for a more detailed explanation of Lasers.

Lasers are described as powerful narrow, monochromatic, coherent and directional beams of electromagnetic radiation (EMR), that can travel long distances with out diffusing. 
Electromagnetic radiation is a form of energy that can travel without a medium like air or water to travel through. EMR can take several forms including heat, visible light, ultra violet, x-rays, radio waves and gamma rays depending on the type of atom and the amount of energy applied. Radiation may be thought of as energy in motion. In Lasers, atoms are made to absorbs energy causing them to jump up to a higher level called an excited state, this in turn causes electrons within the atoms to move and release photons. If photons pass close to another atom the other atom may emit a photon and if that photon passes yet another atom, that atom might also emit a photon. So the number of photons increases very quickly. Lots of photons create electromagnetic waves and as these photons all have the same specific frequency and polarity the photons are precisely in step giving coherence to laser beams. Coherence is a fixed relationship between the phase of waves in a beam of radiation of a single frequency. Most light beans consists of many waves travelling in roughly the same direction but the photons are randomly distributed causing the light to diffuse. Click here to see a clear example of coherent and diffuse light.
Within a Laser Welder electrical energy is used to stimulate the atoms within a confined space. Mirrors are used to bounce photons back and forth passing atoms on the way causing yet more photons to be emitted. This stimulation of the atoms rapidly creates light amplification.The front mirror is semi-reflective so some of the photons escape creating the beam which in this case is intense and hot enough to weld metals.

Other uses for lasers -
There are several different types of lasers,
 the most powerful lasers can quickly cut through solid rock or metal sheets. Some use gases such as helium, neon, argon, and carbon dioxide. Lasers also use semiconductors (Galiodium and Arsenic), solid-state material (ruby, glass) and even chemicals (hydrofluoric acid) in their operation. Some, like the ruby laser, emit short pulses of laser light. Others, like helium-neon gas lasers or liquid dye lasers emit a continuous beam of light.

image courtesy of S McGill
Some everyday uses of lasers- bar code readers, DVD's, measuring equipment, favoured weapon of aliens, eye surgery, cancer treatments, tattoo removal, laser light shows, pointers, atomic clocks to name a few.

Laser Light Show

We have been using lasers at Maker Mends for many years in another capacity.
We use barcodes to track items as they are progress from one department to the other. All Items booked into our system are given a bar coded label then we use a laser barcode scanner to scan items as they move round the building. 
Most barcode scanners consist of three different parts including the illumination system, the sensor and decoder. The sensor in the barcode scanner detects the reflected light from the red light and generates an analog signal that is sent to the decoder. The decoder interprets that signal, validates the barcode using the check digit then coverts it into text.
This converted text is delivered by the scanner to a computer software system holding the relevant information. This system is known as automatic identification and data capture (AIDC).
Bar codes first were used on Wrigley's chewing gum in June 1974.

Laser scanner in use in our office