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4. Віддалеміри – це геодезичні прилади, призначені для
непрямого визначення довжини лінії.
5. Оптичні віддалеміри за конструкцією поділяють на ниткові
й віддалеміри подвійного зображення.
6. Під радіофізичними засобами розуміють прилади для
вимірювання довжин ліній за часом розповсюдження
електромагнітних коливань між кінцевими точками лінії.
Залежно від виду електромагнітних коливань радіофізичні засоби
поділяють на світловіддалеміри і радіовіддалеміри.
V. SPEAKING
Task 1. Look at the text. Give the main points of each passage
of the text.
Distance Measurements with Lasers
Lasers can be used in various ways to measure distances or
displacements without physical contact. In fact, they allow the most
sensitive and precise length measurements, extremely fast recordings
(sometimes with a bandwidth of many megahertz), and the largest
measurement ranges, even though these qualities are usually not
combined by a single technique.
Some of the most important techniques used for laser distance
meters are as follows:
Triangulation is a geometric method, useful for distances in the
range of ≈ 1 mm to many kilometers.
Time-of-flight measurements (or pulse measurements) are based
on measuring the time of flight of a laser pulse from the measurement
device to some target and back again. Such methods are typically used
for large distances such as hundreds of meters or many kilometers.
Using advanced techniques, it is possible to measure the distance
between the Earth and the Moon with an accuracy of a few
centimeters.
The phase shift method uses an intensity-modulated laser beam.
Compared with interferometric techniques, its accuracy is lower, but it
allows unambiguous measurements over larger distances and is more
suitable for targets with diffuse reflection. Note that the phase shift
technique is sometimes also called a time-of-flight technique, as the
phase shift is proportional to the time of flight, but the term is more
suitable for methods as described above where the time of flight of a
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