The Determination of the Parameters of the Electronic Levelling Instrument

It is explained in this paper that the leved difference between two directions of the part below the horizontal axis of the LLMC is determined not in vial, but in electronic levelling instrument. The electronic levelling instrument is a collimator.After reflection on the mercury surface with two backward-lighted perpendicular groups of slits placed on the focal plane form slit images on two piecse of Reticon respectively. The real-time determination of inclination of leved is gotten by measuring the difference of the two positions of the slit image before and after the instrument transposes 180°.The method to determine the scale of Reticon and deflexion error of the slotted plate installation is introduced.