Difference between revisions of "Laser-pop"
| Line 43: | Line 43: | ||
== Bom == | == Bom == | ||
| − | 5x M140 Laser Diode | + | * 5x M140 Laser Diode |
| − | + | * 10x MCP9701A (one mounted on each laser diode, one mounted behind each backwall) | |
| − | 5x LM324 (Quad opamp, DIP package) | + | * 5x LM324 (Quad opamp, DIP package) |
| − | 1x Arduino Mega | + | * 1x Arduino Mega |
Revision as of 17:33, 22 June 2014
| Projects | |
|---|---|
| Participants | Chotee |
| Skills | Electronics, Arduino |
| Status | Active |
| Niche | Electronics |
| Purpose | Fun |
Project to make popcorn with lasers.
Contents
Design
5 lasers shining on a single corn-kernel.
Laser Diodes
The lasers are Casio M140 Diodes. They are known to run at 1 Watt output. There are reports of running them at 2 Watt output, but life-expectancy will be much lower. This project will run them at the conservative 1W.
The light produced is 445nm. Which is blue pushing into the ultraviolet.
Power supplies
The power comes from the mains via a normal PC power supply.
- +5V is used for the lasers. Expected max is 5*1.5A = 7.5A
- +12V is used for Ardunio and opamp logic
Laser power
Powering Lasers is nasty. They are current hungry and will burn themselves up with a constant voltage supply. When warming up, they will draw more and more current for the same voltage, heating up even more, etc. A constant current supply is thus needed.
Each of the lasers is individually controllable. So 5 constant current supplies that can give run 1.5A each. At 1.2A the lasers require 4.45V. Since the idea is to use the 5V power rail of the PC power supply. A low dropout linear voltage regulator is needed. The LT3086 has a dropout of only 330mV and supports up to 2.5A of current. Making it ideal for this application.
Thermal issues
There's a lot of wasted heat. Both the laser-diode and the power supplies will need to be heat-sunk and temperature monitored. Each laser has a 9701A mounted directly on the diode to measure that temperature. The LT3086 has an internal temperature sensor, making it easy to measure as well.
Beam capture
To detect that the beam is not being obstructed by the corn-kernel, a light-sensitive diode is used This diode detects light bouncing off the back wall of a light "capture" device. The diode should drop it's electrical resistance to near Zero in a few micro-seconds after the light hits the back wall. Indicating to the arduino the beam is not obstructed.
The backwall of the sink is a coin spray-painted black. The coins are a known weight 3.91g and known material, copper covered steel. By thermo-isolating the backwall and attaching a thermometer to it, it is possible to typify performance differences and degradation over time of the laser diodes.
The sides of the beam capture will be semi-transparent plastics that will lightup by the light being refracted on the back wall.
Logic
The different elements are controlled by an Arduino Mega.
Status
Bom
- 5x M140 Laser Diode
- 10x MCP9701A (one mounted on each laser diode, one mounted behind each backwall)
- 5x LM324 (Quad opamp, DIP package)
- 1x Arduino Mega
