A method and apparatus for eliminating in at least one light emitter and light detector in a mouse design. This is done by using two conical shaped encoder wheels positioned so that they are almost touching each other. A single light emitter then is used to shine light at the junction, so that it passes through both cones. On the opposite side is a single chip, with two photodetectors integrated on each side. The chip is positioned so that light passing through the first conical encoder impinges on the first photodetector, while light passing through the second conical encoder impinges on the second photodetector. Thus, the two photodetectors can be integrated on a single chip, saving a separate photodetector chip. In addition, only a single LED is required.