An ideal lens for a thermal imaging system would be both lightweight and inexpensive, while immune to incident wavelengths and temperatures. A team of British scientists from the Defence Research Agency in Worcestershire, Pilkington Optronics in Wales and the department of electrical engineering at the University of Edinburgh recently presented two methods for manufacturing a material that may fit both requirements. The material is an arsenic trisulfide refractive and diffractive element that is athermal across the 3- to 5-µm waveband when set in an aluminum mount.