Linear glass scale height gage

摘要

Apparatus for measuring which is adapted for use with a remote digital readout. The measuring apparatus includes an elongated main beam and a measuring device slidably mounted on the beam. The beam includes a transparent ruled scale with markings positioned thereon corresponding to different measurements. Mounted within the device is an electro-optical decoder suspended by a unique flexure arrangement which detects marks as the device is slidably moved on the beam and produces electrical signals which are provided to the remote digital readout system which in turn produces a visual readout of measurement. The measuring device includes a second reader scale having similar markings thereon. In particular, the ruled or measurement scale has markings or lines that are disposed substantially parallel to each other and equally spaced with a first period (number of lines per unit distance), while the markings or lines of the reader scale are disposed parallel to each other and equally spaced with a second, different period (number of lines per unit distance) so that a Moire fringe pattern is established when a source of light is directed therethrough, the fringes of which are spaced in accordance with the difference in scale period.