| 摘要 |
To solve the problem of keeping the sextant vertical by measuring the elevation angle of stars in navigation, the sextant with beam filter is used. This beam filter has a parallel line pattern and thus generates light rays emanating from each luminous object for the observer. (Beam filters, mostly with grid lines intersecting one another, are used in photography, mainly for night pictures. They generate the rays which emanate, for example from street lanterns, in such pictures.) The grid lines of the filter, which are vertical and parallel in the sextant with beam filter, generate horizontal rays in the field of view of the observer. With these rays, each star provides the possibility of adjusting the vertical position of the sextant with respect to the horizon.
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