US Patent 7586586 Fiber optically coupled, multiplexed, and chopped laser rangefinder

A CW phase-delay distance measuring device is described. The device fiber-optically couples an amplitude modulated laser and a detector though MEMS fiber optic switches to provide chopping and multiplexing capability, and to allow measurement of transmit and receive coupling. Phase continuous direct digital synthesizers are used to generate transmit and local oscillator frequencies in an agile frequency diverse way to disambiguate range. Fiber-optic coupling mitigates systematic errors such as variable detector group delay and provides for multiplexing multiple transmit and receive optics onto a single electro-optical system.