Abstract: A data reading device for reading digital data encoded in one or a plurality of data-carrying surfaces directs the output from a single wavelength laser diode at the surface of the data carrier, by focusing the light from the laser using an objective lens. The data may be decoded by sensing anomalies in current flow through a precision shunt which is series connected with the laser diode, because light reflected back off the data-carrying surface is re-directed back to impinge on the laser, and the reflected light will cause anomalies in the current flowing through the diode. Alternatively, the reflected light can be deflected using a prism towards a photo-sensor. In either event, the digital data can then be decoded. A pinhole diaphragm is interposed between the laser and the objective lens, or an objective lens assembly, and the pinhole will function as a point source of light. That point source of light can be re-focused with high resolution on the data-carrying surface.