Device for measuring length: description

Everywhere, the length measuring device is used in various areas: construction, agriculture, personal development, communal 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

Models of a mechanical type are different readings, measured linearly. They are made of metal, fiberglass, have a nylon casing, available in ribbon or roulette. Tools serve to directly fix the length of the line by sequentially reading the readout of the measuring device in the range of the measured object. The final results are obtained after the addition of individual measurements in standard units.

The procedure itself is performed on the body of the object, or with the suspension of a measuring device at a small height fixed in fixing racks. Sometimes, instead of the minimum direct direction between the control points, a certain broken line is measured. To obtain an accurate horizontal position, check the slope of the segment or its individual sections.

In geology and other earth measurements, the most elementary device is a land survey tape with the help of which lengths are calculated with a relative result (inaccuracy is of the order of 1: 1500).

Roulettes

Similar devices for measuring the lengths of lines are quite common, as measuring devices. Domestic roulettes are equipped with scales with nominal sizes from one to one hundred meters. A functional surface is called a canvas or tape. This part has a protective coating against rust and corrosion (varnish, enamel, polymer).

Depending on the initial placement of the scale of the measuring tape, the modification of the roulettes is presented in two variations:

• The starting reference point is shifted from the end part by at least 1.5 cm;
• The initial scale reading is identical to the edge of the working cloth.

Gradation is applied taking millimeters, centimeters, decimeters and meters into account. By the accuracy of the application, there are two groups: the 3rd and the 2nd class.

The average life of roulette functionality from stainless steel is about two thousand dimensional cycles, and of carbon steel - 1500 measurements. Under the full measurement stage is meant the deployment of the web, stretching to full length, stretching, counting, folding the tape. To obtain the most accurate readings, you need to carefully monitor the layout, position and temperature, as well as the constant stretching of the ribbon.

Advantages of roulette

The device for measuring the length called roulette has a number of indisputable pluses. These include:

• Compactness.
• A small weight of the instrument.
• Elementarity of the device and its operation with high accuracy of measurements, in particular short lines.

From the minuses we can note the following:

• Significant laboriousness in measuring certain values.
• It is necessary to clear the working area, especially when measuring the slopes 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 instrument from moisture and friction. With such canvases, roulettes do not rust, the markings on them are not erased.

Range finder optical action

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, a device for measuring the length Is an adaptation that works on a parallactic (alternating) principle.

One value (X or Y) is taken as a constant indicator, the other one is changing. Depending on various factors, the 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 made in the form of a nozzle on the telescope, as an independent device, a built-in element or as an additional detail. A rangefinder of optical action with a thread base and a stable angle is quite popular.

Characteristics of the optical device

The device for measuring length with a constant parallactic angle is one of the simplest measuring instruments. They are equipped with the majority of visual tubes of theodolites and levels. The apparatus consists of a glass plate with a deposited pair of horizontal filaments 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 count is carried out along the extreme filaments of the grid of the vertical rod, and then the distance is calculated according to a special formula, where:

• L - the reporting difference on a rod;
• C - stable value of the range finder;
• K is a coefficient that is one hundred.

The accuracy of measuring the thread range finder is often affected by erroneous reading on the rack, the error is 1/300 - 1/400.

Electronic variant

The device for measuring the length of the electronic type operates on the principle of physical recording of the distance, thanks to electromagnetic waves having a stable propagation velocity, which is known with a high degree of accuracy.

The most popular 10 instruments for measuring length

Frequently used mechanical and optical devices for measuring length are the following tools:

• Roulettes with a cloth of braid and metal.
• Laser or optical range finders.
• Altimeters.
• Levels of different types.
• Theodolites.
• Tachymeters.
• Bussoli.
• Electronic complexes.
• Ground scanners.
• Digital cameras with the function of rangefinder.

For example, a device for measuring the length of a cable can be either a mechanical type (elementary metering calculation by unwinding and measuring certain areas) or in an electronic version. The latter model allows to calculate the cable length in the bay, based on the parameters of the material section, its weight and material of manufacture, 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 threadlike probes, grating blocks and a raytard. 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 how the instruments for measuring the length are called, one can determine their operation principle, the preferred range of application and the accuracy of the final readings.