In order to obtain low uncertainty levels in computer‐controlled electrical precision measurements, the controlling system must not interfere with the measurement system. The optical interface described here provides the two systems with an insulation resistance higher than 1014&OHgr; using two optical fibers, which also allow the systems to be remotely located. The interface treats two dc voltage signals: one of them is used to drive the measuring system, and the other is the result of the measurement and can be read with a relative accuracy of 1×10−4. The interface can be used to automatically drive dc resistance bridges and will be applied to a cryogenic setup having a superconducting quantum interference device as a detector. ©1995 American Institute of Physics.