Thermal experiments are some of the most fun and interesting activities to do with your laser. Understanding some introductory laser light principles detailed in this article will help you get the most thermal power from your unit.
Using lasers it is possible to:
- Pop balloons from a distance!
- Light matches!
- Burn through electrical tape, garbage bags or other plastics!
Introductory laser light principles relevant to thermal experiments:
The burning/cutting power of a laser depends on the interaction between the laser light and the material being experimented upon. The laser beam emitted from the laser is not actually hot in itself. What causes the material being experimented on to ignite, burn or to be cut is the absorption by the material of the energy from the laser light. A comparison can be made with sunlight. It is when objects absorb sunlight that they heat up.
When laser light impacts the material being experimented upon the molecules within the material absorb the laser light energy and start to move faster, the material heats up, the balloon pops, the match ignites and the electrical tape melts!
Based on these laser light principles there are several tips you can follow for maximum thermal performance from your laser.
Tips for Thermal Experiments:
- It is essential to wear proper laser safety eyewear when carrying out any experiments involving ClassIIIb lasers. Ensure that all persons in the vicinity of the experiment are aware of the dangers involved and are wearing proper laser safety eyewear. Be cautious of reflective surfaces anywhere near the possible trajectory of the laser beam and of any other hazards.
- Use dark colored experimental materials – it is best to use black or dark red balloons, black electrical tape, black garbage bags and red tipped matches for experimentation. Black or dark colored objects will absorb the laser light more readily and reflect less of it for maximum thermal effect! Another comparison can be made with sunlight. If you wear a black shirt on a sunny day you will become much hotter than if you wear a white shirt. This is due to the fact that the black shirt will absorb the sunlight while the white shirt reflects the sunlight off.
- Use materials with a matte (non-shiny) surface texture – even if the material you are using is dark in color, if it is also shiny, the energy of the laser light will get reflected off of the shiny coating. Use non-shiny black balloons and other matte materials.
- Keep the laser as well as the experimental material steady – As the thermal effects of a laser depend on the absorption by the experimental material of the laser light it is important to keep both the laser beam as well as the object being experimented on steady. This way the same set of molecules in the material absorbs as much energy in as little time as possible. The best way to achieve this is to mount both the laser as well as the material being experimented upon. You can use a tripod, a retort stand or simply tape the material down and set the laser on an object or table top. The steadier you keep the laser and the material, the better the results you will have.
- Begin at close range – because laser light diverges more and more the further the beam has traveled from the aperture, the laser light will be most powerful close to the aperture. Begin experimenting by keeping the material and the laser close together. However, please be careful not to hold the laser and the material too close together, as the burning of the material might damage the lens on the front of the laser. We recommend 2-3 inches away from the aperture. You can then move the material and the laser further apart in subsequent experiments.
- Use fresh alkaline batteries – the more power your batteries can give the laser, the more power the laser can output and the better will be its thermal capabilities.
Following the above tips will help you get the most from your thermal experimentation.
NOVAlasers wishes you fun exploring!
Copyright 2007 NOVAlasers INC
