Pendahuluan ke rentang prinsip dari fotolistrik pengintai
Itu fotolistrik rentang instrumen bisa be dibagi ke dalam pulsa rentang metode untuk langsung pengukuran waktu dan fase rentang metode untuk secara tidak langsung pengukuran waktu berdasarkan pada metode dari pengukuran waktu t.
The ranging principle of a phase type photoelectric rangefinder is that the light emitted by the light source passes through a modulator and becomes modulated light with varying intensity of high-frequency signals. Calculate the distance by measuring the phase difference (phi) of modulated light propagating back and forth over the measured distance.
Itu fase metode jarak pengukuran adalah setara ke menggunakan a "cahaya penggaris" sebaliknya dari a baja penggaris ke ukuran jarak, dan λ/2 adalah the panjang dari cahaya penggaris.
In a phase type rangefinder, the phase meter can only measure the tail number Δ N of the phase difference, and cannot measure the entire cycle number N. Therefore, it cannot measure distances greater than the optical ruler. To expand the measurement range, a longer ruler should be chosen. In order to solve the contradiction between expanding the measurement range and ensuring accuracy, two modulation frequency, namely two types of optical rulers, are generally used on short-rangefinders. For example, a long ruler (disebut a kasar penggaris) f1=150kHz, λ1/2=1 000m, Used to expand the measurement range, measuring hundreds, tens, and meters; Short light ruler (referred to as precision ruler) f2=15MHz, λ2/2=10m, Used to ensure accuracy, measuring meters, decimeters, centimeters, and millimeters.
Itu mulai kesalahan dari a fotolistrik pengintai adalah dibagi menjadi dua bagian% 3a
(1) Proportional error: an error proportional to the length of the measured distance, mainly caused by frequency error, atmospheric refractive index error, and vacuum light speed measurement error, resulting in errors in the ranging results. The influence of the measurement error of the speed of light on the ranging value can be ignored.
(2) Fixed error: The inherent error of an instrument, independent of the length of the measured distance, include calibration error of zero point error, alignment error between the instrument and the reflector, phase measurement error, amplitudo and phase error, phase phase error phase error phase non-uniformity error of the light-emitting tube, and periodic error. The periodic error terutama comes from the same frequency interference of the internal photoelectric signal of the instrument, and the magnitude of the error is repeated in cycles of the length of the precision measuring ruler.
