Widely, the length measuring device is used in various fields: construction, agriculture, personal improvement, utilities and other industries. All devices, in accordance with the basic principle of operation, are divided into options for mechanical, optical, electronic impact, the functionality of which is based on the physical designation of the distance.
Elementary models
Mechanical type models are various indications measured linearly. They are made of metal, fiberglass, have a nylon body, are available in tape or roulette versions. The tools are used to directly fix the length of the line by sequentially reading the readings of the measuring device in the alignment of the measured object. The final results are obtained after adding the individual measurements in standard units.
The procedure itself is performed on the body of the object, or with hanging a measuring device at a low height, fixed in fixation stands. Sometimes, instead of the minimum straight line between the control points, a certain broken line is measured. To get an accuratehorizontal position check the angle of inclination of the segment or its individual sections.
In geology and other earth measurements, the most elementary device is a survey tape, with which lengths are calculated with a relative result (the inaccuracy is about 1:1500).
Roulettes
Such devices for measuring line lengths are quite common as measuring devices. Domestic roulettes are equipped with scales with nominal sizes from one to one hundred meters. The functional surface is called a canvas or tape. This part has a protective coating against rust and corrosion (lacquer, enamel, polymer).
Depending on the initial placement of the measuring tape scale, the tape measure modification is presented in two variations:
- The starting point of reference is shifted from the end part by at least 1.5 cm;
- The initial reading of the scale is identical to the edge of the working canvas.
Gradation is applied taking into account millimeters, centimeters, decimeters and meters. According to the accuracy of application, there are two groups: 3rd and 2nd class.
The average service life of stainless steel tape measures is about two thousand measuring cycles, and that of carbon steel is 1500 measurements. A full-fledged measurement stage means unfolding the web, pulling it to its full length, stretching, counting, folding the tape. To obtain the most accurate readings, the layout, position and temperatures must be carefully controlled, as well as the constantribbon tension.
Roulette benefits
A device for measuring length called a tape measure has a number of undeniable advantages. These include:
- Compact.
- Light tool weight.
- Elementary nature of the device and its operation with high measurement accuracy, in particular short lines.
Of the minuses, the following can be noted:
- Significant labor input when measuring certain quantities.
- Clearing of the working area is required, especially when measuring the angles of inclination of individual line segments.
The most durable are polyamide tapes or products made of stainless steel. The first option is a transparent plastic that effectively protects the tool from moisture and friction. With such canvases, the roulettes do not rust, the markings on them are not erased.
Optical rangefinder
When working in difficult areas and in hard-to-reach places, rangefinders are often the only effective device for measuring distances. These devices are divided into models of optical and electronic type.
In the first case, the device for measuring length is a device that works on the parallax (alternating) principle.
One value (X or Y) is taken as a constant indicator, the other - changing. Depending on various factors, optical rangefinders are divided into models with a variable base X and a constant angle Y, orvice versa.
The design of these devices is carried out in the form of a nozzle on the telescope, as an independent device, a built-in element or as an additional part. An optical rangefinder with a thread base and a stable angle is quite popular.
Optical specifications
The considered device for measuring length with a constant parallax angle is one of the simplest measuring instruments. Most of the spotting scopes of theodolites and levels are equipped with it. The device consists of a glass plate coated with a pair of horizontal threads located at a certain distance. The plate is placed in the ocular space of the telescope of a geodetic or other measuring instrument.
Using the device in operation, the counting is carried out along the extreme threads of the grid of the vertical rail, and then the distance is calculated using a special formula, where:
- L - reported rake difference;
- C - stable rangefinder value;
- K is a coefficient equal to one hundred units.
The accuracy of measuring with a thread rangefinder is often affected by an erroneous reading on the rail, the error is 1/300 - 1/400.
Electronic version
The electronic type length measuring device works on the principle of physical distance counting, thanks to electromagnetic waves having a stable propagation speed, which is known with a high degree of accuracy.
Top 10 Length Measuring Instruments
Frequently used mechanical and optical devices for measuring length are the following instruments:
- Metal tape tapes.
- Laser or optical rangefinders.
- Altimeters.
- Levels of different types.
- Theodolites.
- Total stations.
- Compass.
- Electronic complexes.
- Ground scanners.
- Digital cameras with rangefinder function.
For example, a device for measuring the length of a cable can be either of a mechanical type (an elementary meter calculation by unwinding and measuring certain sections), or in an electronic version. The latest model allows you to calculate the length of the cable in the coil, based on the parameters of the cross section of the material, its weight and material of manufacture, without unwinding the coil.
Features
A device for measuring the wavelength of light consists of a guide ruler, a light source, a diaphragm, a pair of holes for filament probes, lattice blocks and a reiter. The device captures the measured value by analyzing the developing light beam in the slits of the working eyepiece, taking into account the speed of its appearance and disappearance.
Depending on the name of the instruments for measuring length, you can find out their principle of operation, the preferred scope of application and the accuracy of the final readings.
