If you wanted to determine the distance of an object, you could use a measuring tape. But if you’d rather stay put and measure the distance with minimal effort, another option might be to use a laser rangefinder. Picking one off the shelf is likely to set you back by a decent wad of money, so Berryjam decided to create his own, affordable Arduino-based Open Source Laser RangeFinder (OSLRF-01).
You can get your hands on your own OSLRF-01 from Lightware Optoelectronics Ltd, and this comes either fully assembled and working or as a simple PCB with optics. Then all you need to do is connect the OSLRF-01 to your Arduino UNO. The OSLRF-01 converts signals, which originally travel at the speed of light, into a signal travelling at the speed of sound, and then outputs analog signals comparable to those found on an ultrasonic sensor. These signals can then be interfaced directly with a microcontroller, where data can be collected and processed by ultrasonic signal processing and timing algorithms.
Berryjam’s project sounded slightly stressful because it required some deeper delving into the mechanisms of the sensor, but he’s very generously provided his findings in his project.
OSLRF-01 could be the device to take us to the development of other sensing devices, from proximity sensors and altimeters to obstacle detectors and scanning LIDARs. Berryjam’s project outlines the best ways to connect your Arduino to the OSLRF and then get something useful out of the system. He starts by illustrating a simple way of connecting the two together, and then gives a few details about the timing between time 0 (laser fire) and the returning signals, which have been colourfully decorated with some of Berryjam’s real-world measurements using targets such as fabric (because Berryjam is quite interested in people detection).
There are a few notes of how the Arduino “sees” the signals it receives, and how to eliminate the background noise, and finally how the edges of the system can be smoothed and calibrated. He gives some details on his coding and is planning on making some improvements – so far he’s only implemented some basic ideas so there’s plenty of room for optimisation.
It’s a clever little device and any developments will only lead to a better product. Most impressively, Berryjam has successfully managed to utilise the power of the OSLRF-01 and the Ardunio to create a system capable of completing a ridiculous number of conversions and detections from signals received at the speed of light – and considering light travels 50cm in 1 billionth of a second, that’s quite an achievement.