Thank you for inquiry my Joke Shock Flashlight, Tel: 86-0577-86573661, E-mail: wzsldz@laserkeychain.com
http://www.laserkeychain.com/key-joke-shock-flashlight-37/
The laser distance measuring light waves ranging in ranging mode, with speed c of light propagation in the air between A, B two round-trip time required for time t, then the A, B, the distance D between two points available following said.
D = ct / 2 where:
D – measurement site, the distance B, between two points;
c – speed of light propagation in the atmosphere;
t – the light and from the A, B, once the time required.
To measure the A, B, distance to measure the light propagation time t, according to the different methods of measuring time, the laser range finder is usually divided into the pulse and phase two measurements of the above equation.
Phase-shift laser range finder
The phase-shift laser range finder is the distance from the radio band frequency, amplitude modulation, the laser beam and measure the phase delay of the modulated light and from the measured line generated by the wavelength of the modulated light, conversion phase delay represented. Using the indirect method of determination of the light by the time required between the measuring line, as shown below.
The picture shows the phase-shift laser rangefinder ranging schematic
The phase-shift laser range finder general application in the subtend. Because of its high accuracy, usually as a millimeter, to the reflected signal, and the determination of the target limit on a particular point commensurate with the instrument accuracy of this rangefinder configuration known as the reflection of the goals of cooperation mirror.
Modulated light angular frequency ω, the phase delay to be measured round trip distance D is φ, the corresponding time t can be expressed as:
t = φ / ω this relationship into the distance on D can be expressed as:
D = 1/2 ct = 1/2 c · φ / ω = c / (4πf) (Nπ + Δφ) = c/4f (N + ΔN) = U (N +) type in:
φ – the signal from the measuring line time to produce the total phase delay.
ω – angular frequency of the modulated signal, ω = 2πf.
U – per unit length, the value is equal to 1/4 modulation wavelength
N – measuring line contains the number of modulation half-wavelength.
Δφ – Signal from the survey line time to produce the phase delay of less than π part.
ΔN – measured line contains the fractional part of the modulation wave is less than half wavelength.
ΔN = φ is / ω
A given modulation and standard atmospheric conditions, the frequency of c / (4πf) is a constant, the distance measurement into the measurement line contains the number of half-wavelength measurement and less than half the wavelength of the measurement of the fractional part of the Measure N or φ, due to the development of modern precision machining technology and radio direction finding technology, the measurement of φ to achieve high accuracy.
Measured less than π phase angle φ, by different methods to measure, usually the most widely used is to delay the phase measurement and digital mapping, short-range laser rangefinder using digital phase measurement principle to obtain φ is.
. Bookmark the
.
0 comments:
Post a Comment