New Focus Inc. has introduced three photodetectors that run on battery power and come in compact packages. The femtowatt photoreceiver has a gain of 1011 V/W, making it suitable for low-light and fluorescence detection. The large-area photoreceiver has a slim profile that allows the user to move it quickly in and out of the beam path and simplify alignment. The nanosecond photodetector is based on a design that many researchers have used to make their own detectors. The company says it is more convenient and less expensive than building one from scratch.