This video details the design and construction of a second-generation portable, long-range laser projector capable of displaying rasterized images and animations. Building upon a previous single-color text projector, this new version implements a hybrid scanning system that combines a high-speed spinning polygon mirror for the horizontal axis with a galvanometer for vertical control, significantly increasing the resolution to 180x120 pixels. The project incorporates an RGB laser module, a powerful Teensy 4.0 microcontroller, and a custom-designed PCB. A key challenge was the attempt to create an analog driver for variable brightness, which was ultimately replaced with a simpler digital on/off system, resulting in an 8-color palette. The entire system is housed in a compact, portable enclosure made of aluminum and wood, powered by a 24V tool battery. Testing demonstrates successful projection of animated GIFs at distances exceeding 100 feet.
Building a High-Resolution RGB Laser Projector
0:00:19 - Upgrading the Original Concept: The project aims to improve upon a previous laser projector by tackling its key limitations: low 12-line vertical resolution, a single green color, and an inability to display graphics. The goal is to create a portable, long-range device that can project rasterized images, animations, and simple videos.
0:02:53 - Boosting Processing Power: The original Arduino Nano is replaced with a Teensy 4.0 microcontroller, which has a 600 MHz processor (37.5 times faster). This upgrade eliminates the processing bottleneck and allows for much higher horizontal resolution and cleaner code.
0:04:12 - A New Hybrid Scanning System: To overcome the resolution limits of a single spinning mirror array, a new system is devised. It uses a rapidly spinning polygon mirror (from a laser printer) for the horizontal scan and a galvanometer (galvo) for the slower, more precise vertical stepping. This allows for high resolution without sacrificing horizontal scan speed.
0:05:49 - Controlling the Vertical Axis: A 50k PPS galvanometer, controlled by a Digital-to-Analog Converter (DAC), manages the vertical movement of the laser beam. The code is written to draw even-numbered lines on the galvo's downward sweep and odd-numbered lines on its upward return sweep to create a full image.
0:08:26 - Pushing the Resolution Limit: The system is tested and found to achieve a stable vertical resolution of 120 lines before the refresh rate becomes unpleasantly low (strobing). The final operational resolution for animations is 180x120 pixels.
0:09:35 - The Challenge of Full Color: An RGB laser module is integrated to achieve color projection. The initial goal of creating a true analog driver for variable brightness control failed because available DACs were too slow (<100ns settling time required). The project pivots to a digital on/off driver, limiting the output to an 8-color palette (including black).
0:12:22 - Displaying Animations: A custom script is written to process animated GIF files. It breaks the GIF into frames and "posterizes" each pixel to the nearest of the 8 available colors, generating 2D arrays that the microcontroller can read and project.
0:13:17 - Creating a Portable Power Source: To make the device portable, a power system is built around a single 24V string trimmer battery. This required a step-down converter for the laser drivers and a specialized DC-DC converter to generate the positive and negative 24V rails needed by the galvanometer.
0:14:22 - Professional Final Build: The messy prototype is consolidated into a sleek, durable enclosure. This involves designing a custom PCB in KiCad and using CNC-machined aluminum plates for the base and lid, with stained wood for the side walls.
0:17:53 - Long-Range Outdoor Testing: The projector's performance is tested outdoors at night. It produces a sharp, bright image on a house at 50 feet and is still clearly visible on a brick wall at nearly 100 feet and on trees over 200 feet away.
0:18:47 - Verdict and Future Improvements: The project is a success, creating a unique device with an order of magnitude better resolution than its predecessor. Potential future upgrades include a more powerful laser module, a faster motor to increase the refresh rate, and a cooling fan to manage heat during extended use.