Everywhere, a device for measuring length is used in various fields: construction, agriculture, personal equipment, utilities and other industries. All devices in accordance with the basic principle of operation are divided into mechanical, optical, electronic effects, the functionality of which is based on the physical designation of the distance.
Elementary models
Models of a mechanical type are various readings measured linearly. They are made of metal, fiberglass, have a nylon body, are available in tape or tape version. Tools are used to directly fix the line length by sequentially reading the reading of the measuring device in the alignment of the measured object. The final results are obtained after adding up the individual measurements in standard units.
The procedure itself is performed on the body of the object, or with the suspension of the measuring device at a low height, fixed in fixation tripods. Sometimes, instead of the minimum direct direction between the control points, a certain polyline is measured. To obtain an accurate horizontal position, check the angle of inclination of the segment or its individual sections.
In geology and other earth measurements, the most basic device is the land survey tape, with which lengths are calculated with a relative result (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 canvas or tape. This part has a protective coating against rust and corrosion (varnish, enamel, polymer).
Depending on the initial placement of the measuring tape scale, the modification of the tape measures is presented in two variations:
- The starting reference point 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 the application, there are two groups: 3rd and 2nd class.
The average resource of the functionality of roulettes made of stainless steel is about two thousand dimensional cycles, and from carbon steel - 1,500 measurements. By a full-fledged measurement step is meant the deployment of the web, stretching to full length, stretching, counting, folding the tape. To obtain the most accurate readings, it is necessary to carefully monitor the layout, position and temperature, as well as the constant tension of the ribbon.
Roulette advantages
A device for measuring length, called roulette, has a number of undeniable advantages. These include:
- Compactness.
- Light weight tool.
- The 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 complexity in the measurement of certain quantities.
- Cleaning of the working area is required, especially when measuring the tilt angles of individual line segments.
The most durable are polyamide tapes or products made of stainless steel. The first option is a transparent plastic, which effectively protects the tool from moisture and friction. With such canvases, roulettes do not rust; the markings on them are not erased.
Optical Rangefinder
When working in difficult areas and in inaccessible places, often the only effective device for measuring distances are rangefinders. These devices are divided into models of optical and electronic type.
In the first case, a device for measuring length is a device that works on a parallactic (alternating) principle.
One value (X or Y) is taken as a constant indicator, the other is changing. Depending on various factors, optical rangefinders are divided into models with a variable base X and a constant angle Y, or vice versa.
The design of these devices is in the form of nozzles on the telescope, as an independent device, an integrated element or as an additional part. The optical rangefinder with a filament base and a stable angle is quite popular.
Optical device specifications
The device under consideration for measuring length with a constant parallactic angle is one of the simplest measuring instruments. Most telescopes of theodolites and levels are equipped with it. The apparatus consists of a glass plate coated with a pair of horizontal threads located at a certain distance. The plate is placed in the eyepiece of the telescope of a geodesic or other measuring instrument.
Using the device at work, the countdown is carried out on the extreme threads of the grid of the vertical rail, and then the distance is calculated by a special formula, where:
- L is the reported difference on the rail;
- C is the stable value of the range finder;
- K is a coefficient that is equal to one hundred units.
Erroneous readout on the rail often influences the accuracy of measurements with a thread range finder, the error is 1/300 - 1/400.
Electronic variant
A device for measuring the length of an electronic type works on the principle of physical distance accounting, thanks to electromagnetic waves having a stable propagation velocity, which is known with a high degree of accuracy.
Most popular 10 length gauges
Frequently used mechanical and optical devices for measuring length are the following instruments:
- Roulettes with a web of braid and metal.
- Laser or optical rangefinders.
- Altimeters.
- Levels of different types.
- Theodolites.
- Tacheometers
- Bussoles.
- Electronic complexes.
- Ground scanners.
- Digital cameras with rangefinder function.
For example, a device for measuring cable length can be either a mechanical type (elementary metering calculation by unwinding and measuring certain sections), or in an electronic version. The latter model allows you to calculate the length of the cable in the bay, based on the parameters of the material section, its weight and manufacturing material, without unwinding the coil.
Features
The device for measuring the wavelength of light consists of a guide ruler, a light source, a diaphragm, a pair of holes for filamentous probes, trellised blocks and a rafter. 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 what the length measuring devices are called, you can find out their principle of operation, the preferred scope and accuracy of the final readings.