The configuration and function of the device have been described in detail. Using the device, we can verify all the main performance parameters of existing optical theodolites. We solve the problem of small-angle measurement by using one linear CCD. To overcome the inherent limitation imposed by CCD pixels to measurement precision, we proposed asubdivision method of interpolating edge pulse. By using this method, the ultimate error can be controlled within 0.5" .We also proposed a novel "N" reticule. The reticule cooperates with linear CCD can easily accomplish two dimensional synchronous measurement of the angular deviation. For improving reading precision, we applied some image recognition techniques such as image enhancement, practical entropy threshold setting and sifting-continuity matching. The readingprecision has been increased to 1" . The measurement uncertainties have been evaluated at the end of the paper. The results show that the uncertainty indexes of the device can fully meet the requirements of verification work. The device has the advantages of small volume, high automation, convenient operation and good reading repeatability. It has been used in many measurement stations successfully.
展开▼
