Detecting single photons can be seen as the backbone of cutting-edge applications like LiDAR, medical imaging, and secure optical communication. Miss one, and critical information could be lost forever. That’s where FPGA-based instrumentation comes in, delivering picosecond-level precision with zero dead time. If you are intrigued, consider sitting in on the 1-hour webinar that [Dr. Jason Ball], engineer at Liquid Instruments, will host on April 15th. You can read the announcement here.

Before you sign up and move on, we’ll peek into a bit of the matter upfront. The power lies in the hardware’s flexibility and speed. It has the ability to timestamp every photon event with a staggering 10 ps resolution. That’s comparable to measuring the time it takes light to travel just a few millimeters. Unlike traditional photon counters that choke on high event rates, this FPGA-based setup is reconfigurable, tracking up to four events in parallel without missing a beat. From Hanbury-Brown-Twiss experiments to decoding pulse-position modulated (PPM) data, it’s an all-in-one toolkit for photon wranglers. [Jason] will go deeper into the subject and do a few live experiments.

Measuring single photons can be achieved with photomultipliers as well. If exploring the possibilities of FPGA’s is more your thing, consider reading this article.

Although the Earth’s magnetic field is reliable enough for navigation and is also essential for blocking harmful solar emissions and for improving radio communications, it’s not a uniform strength everywhere on the planet. Much like how inconsistencies in the density of the materials of the planet can impact the local gravitational force ever so slightly, so to can slight changes impact the strength of the magnetic field from place to place. And it doesn’t take too much to measure this impact on your own, as [efeyenice983] demonstrates here.

To measure this local field strength, the first item needed is a working compass. With the compass aligned to north, a magnet is placed with its poles aligned at a right angle to the compass. The deflection angle of the needle is noted for varying distances of the magnet, and with some quick math the local field strength of the Earth’s magnetic field can be calculated based on the strength of the magnet and the amount of change of the compass needle when under its influence.

Using this method, [efeyenice983] found that the Earth’s magnetic field strength at their location was about 0.49 Gauss, which is well within 0.25 to 0.65 Gauss that is typically found on the planet’s surface. Not only does the magnetic field strength vary with location, it’s been generally decreasing in strength on average over the past century or so as well, and the poles themselves aren’t stationary either. Check out this article which shows just how much the poles have shifted over the last few decades.