1. TRYING TO MEASURE THE SPEED OF LIGHT WITH AN ARDUINO
We know that measuring the speed of light with an Arduino is possible. It’s just that the implementation is hard.
Last month we saw [Udo]’s blinkenlight shield that can be used as a line scan camera. It’s a neat piece of kit, but [Udo] really wants to submit something for the Buildlounge laser cutter giveaway, so he figured measuring the speed of light would be an easy project. If a kid and a chocolate bar can do it, surely it can’t be too hard.
[Udo] hit upon the idea of pulsing a laser pointer and measuring the time of the reflection. Because his blinkenlight shield can be used as a light sensor, all that’s needed is a mirror and a pretty long line of sight. There’s a few problems with the setup though: with the Arduino running at 16 MHz, a photon will travel 19 meters in one clock cycle.
Even with some very clever coding, we’re not really sure detecting an emitted photon is possible at such (relatively) slow clock speeds. We’re thinking [Udo] could source a few hundred meters of optic fiber so the entire experiment could fit on a desk, but feel free to drop a note in the comments if you’ve got a better idea. [Udo]’s demo of his blinkenlight/laser mashup is after the break.
2. LASER RANGEFINDER RECEIVERS WITH RANGE PROCESSORS
The 7558 and 7555 Series Rangefinder/Processor assemblies comprise a high performance Model 758A or 755A receiver with compact support electronics to provide corrected range data to a mother system. The serial range data output is calibrated using AMI’s patented technology to mitigate the effects of range errors from various sources including walk due to return signal amplitude variations. Exceptional sensitivity allows the use of low power lasers, or alternatively, long range operation. The modules provide high voltage bias, time programmed gain with noise tracking threshold, first, last, and strongest pulse selection and range gating. The 7558 series offers a TE cooler controller and heatsink. There also are a number of user controlled options via the serial interface. The compact layout allows positioning at the optics for minimum overall system size.
- High Sensitivity down to 3nW (7558 Series)
- Fast Recovery from Overload
- Optimized for Multiple Targets
- Cooled Detector (7558 Series)
- Time Programmed Gain with Noise Tracking Threshold
- High Speed Range Counter
- Range Walk Correction to 1m RMS
- Digitally adjustable: APD Bias, Range Gates, False Alarm Rate
- Built-in HV Bias Supply for APD Detector
|Model||Detector Ø||Sensitivity (Typ)||Multiple Target Resolution (1:1 Low Gain)||Multiple Target Resolution (1:1 High Gain)||Dynamic Range||Min/Max Range|
|7555-04||200µm||5nW (20ns)||15 meters||30 meters||106:1||50m to 65km|
|7558-03||80µm||3nW (6ns)||10 meters||20 meters||107:1||50m to 65km|
|7558-04||200µm||5nW (6ns)||10 meters||20 meters||107:1||50m to 65km|
Interface test board available for the Model 7555
Application Notes available for most models. Please contact us to request a copy of these ITAR controlled documents.
Specifications are typical and are subject to change without notice. See data sheet for details.
In the event these commodities will be transferred to a “foreign person” as defined in 22 CFR 120.16,either outside or within the United States, a validated US State Department license is required.