| 摘要 |
From a radiation source (S) light is transmitted and picked up by an observer (O) who has a theodolite (T) for measurement of the angle (V) formed by the radiation (SO) with the horizontal plane. This angle can then be used to determine the horizontal distance (L) between radiation source and observer. - Due to air density variations between source and observer, refraction of the light beams occurs. This means that the measured angle (V) invariably has an additional value which requires accurate determination to arrive at the height angle. Thus, two sources of e.m. radiation with different frequencies are located one above the other at the one measurement point. The distance between them is varied until a beam from one of them bisects one from the other at the second measurement point, and this distance is then measured as an extent of dispersion between the beams. (Provisional Basic advised week K08)(1/5) |
