MARKED CARD READER

摘要

A marker card reader having a lensless optical detection system with fixed angle illumination and detection, the sensitivity of which is independent of the associated frequency response. The optical detection system (48) includes a radiation source (50) to produce radiation and a radiation detector (56). A target plane is positioned so that the radiation source directs radiation toward the target plane (66). The detection source is positioned to sense radiation reflected from the target plane. An optically opaque body (108) is positioned between the optical detector and the radiation source to prevent incident radiation from being sensed by the optical detector.