Explanatory drawing showing the handwheel and transparent dial; the lead screw shaft; the LCD display and the printed circuit board with the light source, receptor and disk. The traditional engraved dials used on machine slides were difficult to read: 'Digidial' was designed to overcome this problem. The device uses a phot-cell, which registers the amount of light through the transparent dial. Movement is also registered and displayed on a remote screen in addition to the LCD display.
© Science Museum / Science & Society Picture Library