Abstract: A keyboard that has two adjacent rows of emitters opposed by two adjacent rows of detectors that is environmentally sealed and has no moving parts. This said keyboard has a field changeable coded indicia so a scan pattern, ambient reference level or other application specific variables can be changed without breaking the environmental seal or powering down the keyboard. Further, the different said scan patterns can include scanning the finger position by multiple emitter detector pairs at angles other than ninety degrees to give a cross check on detection. These said scan patterns can be further optimized to scan angled sets of keys and to adjust to different ambient light conditions so errors can be detected by the emitter detector pair closest to detection of a finger. Also another said scan pattern can include, that both emitter detector pairs before and after the detected finger position must show a no finger detection condition to be a valid finger detection.