Solar Laser Projector
Energy: Solar Project + Final Project
Energy: Solar Project + Final Project
For my solar project, I would want to use this opportunity to revisit a prototype for an Autonomous Protest Vehicle that I started back in 2019. The vehicle is meant to use laser projection to display protest messages. Therefore, this project will focus on using a solar panel to power a laser diode, which would act as the light source for a later projection.
In class I shared two different green lasers I had considered using, but after doing some research I’ve decided these are two intense and therefore am switching over to a less powerful red laser diode.
Bill of Materials
5mW Laser Diode — $5.95 // 6V 2W Solar Panel — $19.95 // Arduino Uno — $18.40
Fabrication
Laser diode specs https://www.adafruit.com/product/1054
5mW laser
2.8 - 5.2V DC voltage input
25mA max current draw
The Numbers
So right now I have numbers but I’m confused by them.
Using a multimeter with my panel under the light of the solar cart I found that it has an Open Circuit Voltage (OCV) of 5.7V and a Short Circuit Current (SCC) of .034A. Meaning that the approximate upper limit of power that can be generated from this panel is .193W.
From the images below the circuit that this panel will be used to power uses .364W when one of the laser diodes is on.
Videos
It works! Both with the light from the solar cart and outdoors. I changed the speed of the blink for demonstration purposes.
Note: based off of the measurement I took with my multimeter and the measurement read on the USB stick it shouldn’t work. The max theoretical power the panel can generate is much lower than what even the Arduino alone needs. I will be double checking the SCC of the panel.
Next steps:
In order to use lasers as a projector element, you need to filter it through a concave lens and a transparent image slide. The number of filters the laser passes through dims the strength of the light. I am hoping to utilize this factor to actually safely use the more powerful green lasers I had originally wanted to use. I also will be working on a more thoughtful fabrication body that is reflective of how I want the device to be used.
Below is a diagram of how the components need to turn a laser into a projector.
References for this Project:
Project Update: 05/05/2020
Project Update: 05/05/2020
The above is the rig I created to turn my solar powered laser pointer duo into a projector duo. The setup adds a concave lens appropriated from the view finder of a disposable camera that expands the beam so it can shade the entirety of the image slide. The image on the right is the device outside in sunlight. The beams I am using are only 5mW and while normally pretty visible in day light passing them through any sort of filter really dims them, therefore I also created a rig that was meant to demonstrate what this projector could look like if a more powerful laser was used.
In addition to green light being more easily perceived by the human eye, this laser is a 100 mW beam. 100 mW is a potentially dangerous beam strength. I am still trying to understand how to work with it safely. This setup uses 3 concave lenses to expand and decrease the strength of the beam. Unlike the other rig these filters are enclosed so that viewers are not exposed to them before they pass through the filter.
I do not know if having the beam pass through three filters is actually making it safe to look at so I still laser safety glasses while testing it and taking the above images.
In creating and testing these rigs I have also come to terms with an inherent conflict in the design: the lasers are most effective in the dark, but the device is meant to be solar powered. I had hoped that using a powerful enough laser could mitigate this conflict but it seems as if to bring the laser down to a safely viewable standards makes it too dim to be utilized in the sunlight.
There are two pivot options for future designs. Move away from solar or have this charge during the day and then use that energy at night. I am more partial to the latter option, even though I was originally very against creating a night time object. The object is meant to be an attractive and simplistic guerilla protest tool. What I imagine is strategically placing these during the daytime, letting them charge up during the day, and then once it gets dark turning on and showing this message.
