This article is devoted to instruments that measure a parameter such as height. However, before proceeding with the description of the tool itself, let's figure out what this indicator is.
Concept of height
The mentioned parameter is a relative value, that is, this value is always determined relative to something. Most often it is measured relative to sea level, which means that the line of the sea surface is taken as a reference point.
Such a system resembles the determination of the degree of water in Celsius, when the reference point is the temperature of the transition of water from liquid to solid, and vice versa. Also with height measurement, a value above sea level is considered positive, and a value below is considered negative. In special cases, the reference point can be any other surface. For example, no one will measure the height of a house relative to sea level, here the reference point is the
surface of the earth on which the building is built. All the special cases are measured by the same principle: the height of a tree, structure, etc. But the height of a mountain or any point on the
earth’s surface, as well as an object flying in the atmosphere (airplane, helicopter, etc.) is measured relative to sea level. The reader may ask the question: “What device is used to measure relative height?” You will find the answer to this question if you read the article to the end.
Instrument for measuring relative height: development history and main types
Since ancient times, people used a tool such as a level to build and determine terrain. This device has become the basis for the modern measuring mechanism. A tube was attached to the ancient level, and it turned out the most elementary device for measuring the relative height, which was called the level, which means "level out". The elementary level is a horizontal bar and a vertical bar to which a plumb line is attached. However, with the development of science, tools are being improved. The device for measuring height was no exception. So, modern levels can be divided into three main groups. The first is the most common, it includes devices based on high-quality optics. The second group is laser devices. These instruments are characterized by high-precision measurements. And the third - the "youngest" - are digital levels.
Optical measuring instruments
Such a device is a cylindrical level (or compensator) and an optical system, which is placed in a metal casing (pipe). A level is required to set the line of sight to the horizontal position.
For measurements, the level is mounted on a tripod with a reference platform. The cylindrical level is an ampoule with a liquid (ether, alcohol). The part of the space filled with alcohol vapors is called the level bubble. On the upper surface of the ampoule, a scale is plotted with a step of two millimeters, its middle point is called the zero line.
Laser level
In these devices, in addition to optical systems, laser LEDs arrived, but, in fact, the named device is not much different from optical. Its main feature is a very thin, perfectly even beam projected onto the measured surface. This greatly simplifies the height determination process.
Digital instrument for measuring relative height
This tool is significantly different from its predecessors. He not only changed his appearance and internal structure, but also significantly expanded his capabilities. A digital level is a measuring device that is capable of not only measuring, but also projecting rays, planes onto any surface. This tool is simply irreplaceable during construction and repair work. The mentioned device is characterized by high measurement accuracy and ease of use, even a beginner can use such a tool.
The principle of operation of the digital level
The basis of the device under consideration are the electromagnetic system of the pendulums and the LED (laser) optical system, which is designed to project laser beams in the form of points or lines. One such device can project several planes at once, which is very convenient during construction. To ensure the accuracy of measurements in a digital level , a metal pendulum is used, which aligns the entire electronic and optical parts of the device with respect to ground level. Even if the device is inaccurate or moved during operation, the pendulum will set the circuit parallel to the ground, and the projected surface will remain accurate. Consider how this happens. Under the pendulum there are several electric or natural magnets. Thanks to the created magnetic field, the swing of the pendulum is prevented when the level is changed. When installing the device, this element swings freely. However, when passing through a magnetic field in a material (metal), an electric field is induced that transforms into thermal energy, which inhibits the entire system.
The optical system of the device is based on LEDs that create horizontal, vertical and diagonal rays. Passing through a system of lenses, they are converted into lines, which are projected on the measured surfaces.
Advantages and disadvantages of digital levels
The main advantage of such a device is its simplicity and visibility, as well as the ability to carry out work with the base plane at several points simultaneously. We should also mention the possibility of constructing horizontal and vertical planes, and immediately in different directions.
The disadvantage of this device is its high cost. Of all of them, only third-class devices are comparable in price to optical levels. They can only be used when carrying out repair work indoors, where high accuracy does not play a big role. For example, for marking floors, walls, ceilings. And for conducting geodetic measurements and for marking up grandiose objects under construction, instruments of the first or second accuracy class are required. However, the range of use of such tools is still limited to 600 meters. If you need to measure over long distances, you should use optical levels.
Classification of digital levels
1. Point device for measuring height. It resembles a laser pointer, that is, it projects one or more points onto the measured surface.
2. Static, or positional digital level. This device has two sources projecting laser beams onto perpendicularly placed prisms that convert them into two visible planes. The result is two planes intersecting with a cross. In the case of complex optical systems containing more than three semiconductor diodes, it becomes possible to project a large number of planes, which is very convenient when working with multidimensional objects. In addition, the more planes, the more craftsmen can engage in repair or construction work. Positional levels are also equipped with a “laser plummet” function. These are additional diodes, thanks to which you can direct the beam simultaneously to the floor and ceiling.
3. Rotational digital level. In such a device, the laser is attached to the shaft of the electric motor, that is, it can rotate 360 degrees. In addition, in such devices (instead of a prism) a focusing lens is used. As a result, instead of a plane, a person sees a small point, but when turned on, a continuous line is projected across the entire working area or area of the room.