Microminiature true-zero-order wave plates for use with laser sources are available from Tower Optical Corp. The series AO-0.5-TZ square wave plates measure 0.5 x 0.5 mm, are approximately 90 µm thick and are made from crystal quartz. The company says the size of the devices allows packaging of a complete laser handling system in a small transceiverlike housing. They have a short optical path designed for temperature stability and extended bandwidth. The surface has an antireflection coating for maximum transmission at the specified wavelength. The primary wavelength is 1550 nm.