The stylish way to blind everyone in the club
As a lifelong fan of Mad Max, I’ve got a soft spot for double rider leather jackets.
I’ve never had an excuse to own one, until I saw Shih Wei Chieh’s Laser Jacket made for Japanese musician Kazuya Yoshii:
Nothing could be cooler than that. I’ve always wanted a leather jacket, and I’ve got some experience with lasers, so why not combine the two and make my own?
Our plan will be to 3d print housings for the red laser diodes, solidly attach them to the leather jacket, build the electronics needed to control the lasers, and power everything with a LiPo battery. Wiring will be hidden in the inner lining of the jacket. We will try to get as much laser coverage as possible: down both arms, across the shoulders and upper back, and the chest. We will limit ourselves to 128 lasers, since it will be hard to address more than with the limitations of the Arduino Nano.
A similar project has already been fully documented, which will make great reference for our version.
Our process will be:
The key to this project is sourcing 128 small red laser diodes. Luckily Chinese suppliers produce a standard red laser diode in mass quantities for very cheap ($0.20/ea). We need 128 of them:
For ease of maintenance it would be nice to be able to easily swap out laser diodes without having to cut wires. My preferred connector for these situations is the JST series. In this case, since the lasers are small and numerous we will go with the Micro JST PH 1.25:
An Arduino Nano will be the brains of the project:
Each of our lasers will need a PWM signal to control its brightness. The Arduino Nano only offers 5 PWM outputs, so we will need to expand upon this. We can achieve that with PCA9685 16-channel PWM drivers:
If we group 4 laser diodes together (sharing the same brightness amongst them, and keeping them physically close to each other), we can get away with 32 PWM channels to cover all 128 laser diodes. We will use 2x PCA9685, one for each side of the jacket.
Each laser diode will draw a maximum of 20mA (according to the specifications) at 5V. We need to be able to provide 2.56A if every laser is at full brightness. And we want to be able to do this for a while, so we will need a high capacity source. LiPo batteries make the most sense here: they can provide a lot of current for a reasonably long time, and are readily available thanks to the growing popularity of drones and the RC hobby in general.
Our battery puts out 11.1V, we need a stable 5V for our Arduino and the laser diodes. A BEC (Battery Eliminator Circuit) can take care of this:
For safety we will use an in-line 3A fuse:
Since this is a one-off project, protoboards will work fine for the circuitry:
The laser diodes being small means M2 screws and nuts will be ideal:
And most importantly, we need a jacket. eBay to the rescue:
(In retrospect, a more expensive jacket would have made sense considering how many hours were sunk into this project…)
Each laser diode will be contained in its own housing, with screws and a backing plate to hold it against the jacket:
We print out enough to make 128:
After soldering and heat-shrinking the JST connectors to each laser diode, we can begin assembly:
We repeat this 128 times.
The first step is to mark the jacket with masking tape in all 128 locations. Once we have a good distribution, we poke 3 holes for the screws using one of the housings as a template. Once all the holes are poked, we can attach the laser modules:
We repeat this 128 times.
The overall design of the electronics is quite simple. Starting with power, we will hide the LiPo battery in a pocket, along with the inline fuse and an on/off switch:
The power circuit is simple, we take the 11.1V from the LiPo and split it off to a 5V Buck regulator for the Arduino Nano, and we use the BEC to power the more-demanding laser diodes:
Each channel of the PWM controller drives a transistor (2N2222) which provides power to the laser diodes. 32 channels is total, across 2 PWM boards:
The Arduino Nano tackles the simple job of sending an I2C signal to the PWM controllers:
Since we have a lot of exposed metal on our circuits and all of the laser housings, we wrap everything up with kapton tape to provide insulation:
With 128 lasers spread at various distances, we need a way to keep things from getting tangled. The simple solution is to create braids to contain the wiring for groups of lasers which are in close proximity to each other:
Clearly this jacket should not be worn at an airport or other security checkpoint.
We are now ready to program the Arduino Nano to control the lasers. The simplest thing would be to have every laser driven at full power, but we have the opportunity to program some animations by controlling the brightness of individual groups of lasers.
There is one lighting effect which gives me the chills each time I see it. Fluorescent preheat flicker:
We will recreate this effect - when the suit is first turned on the lasers will flicker preheat-style before reaching full intensity.
Another lighting effect that would be nice is a sparkling effect, where lasers fade in and out randomly.
With multiple lighting effects available, we can use a joystick hidden in one of the pockets to cycle between modes and adjust laser brightness:
Another improvement would be to add a small microphone to the back of the jacket and use it for beat detection on any music that is playing in a venue:
The lasers could then be programmed to sync their brightness to the beat (not yet implemented).
Additional lighting patterns could be programmed, for example a sweeping pattern that flows from one hand, up the arm, across the shoulders, and down the other arm, before repeating in reverse (not yet implemented).
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