Here’s a clever idea for digital calipers: instead of a traditional battery, the SuperSolar caliper from Mitutoyo America (www.mitutoyo.com; Aurora, IL) uses a solar battery that charges a super capacitor. The solar battery requires just 60 lux to charge, and when used in low light conditions, it still works because that’s when the capacitor kicks in. It provides a 0.01-mm resolution with ±0.02-mm accuracy. It is IP67-rated, which means that it is dust proof, chip proof, and coolant proof. Have light? Then you’ve got measuring power.