Theodolite: device, purpose, varieties

When performing engineering and construction and construction work, accuracy is very important. And it is inadmissible to do complex constructions, as they say, "by sight" in such cases. There is a large number of geodetic instruments that allow you to perform meticulously measurements and calculations. For example, levels, measuring tapes, tachometers and other devices.

Among them is the theodolite. This is the main high-frequency device, which ensures the correct work of surveyors. Theodolites are optical and electronic. They perform an angular survey, measuring both horizontal and vertical angles.

Areas of use

This geodetic device is used in the following areas:

• When it is necessary to build topographic maps and plans or an entire network of geodetic points on a triangular area of the terrain;
• When it is necessary to determine the location of points on the site with respect to each other;
• For performing construction work, for example, when it is necessary to fix the horizontal or vertical construction of structures (piles, columns, etc.);

It is not difficult to work with a theodolite. To perform complex calculations and measurements, you need to acquire certain skills.

Classification of devices

Theodolites have several varieties. It:

1. Optical theodolites. Devices of this type are the most common. They are accurate and reliable for use in the field. Theodolites of this species are popular among surveyors. They have a number of advantages over electronic counterparts: they do not need power elements for work and are easy to apply. Optical theodolites can perform work in a fairly wide temperature range, even at a negative temperature. Theodolites of this species have minimal possibilities. Reports are performed on a scale. If the tool does not contain internal memory, then it will be necessary to acquire a field log in which all data will be recorded.
2. Laser theodolites also do not differ in the complexity of operation. In such a device, a laser beam is used, which serves as an accurate indicator. The device combines the functions of two devices - a sighting device and a high-frequency electronic instrument for measurements. The device is equipped with a powerful processor that performs all calculations and displays the results of the device. The ease of use and convenience of such a theodolite are obvious.
3. Digital theodolites do not use vertical and horizontal circles that contain a gradual markup. Bar-code disks are used instead. The device performs measurements in an automated way. The design of such a device contains a memory device. Theodolite stores data in the internal memory. With digital theodolites, do not work in difficult climates and low temperatures, since these devices contain power supplies and an LCD display.
4. Phototheodolites and cinodolites belong to the category of instruments having a specific purpose. The design of the former unites the theodolite and the camera, which defines the topographic coordinates. The main purpose of cinema theodolites is to fix the trajectory of the movement of objects both on the ground and in the air.

Device design

By their design theodolites are divided into the following types:

• Simple. In theodolite schemes, alidade and limb rotate independently.
• Repeating. Rotation of the limb and alidade can occur both individually and together.

Theodolites are divided according to their accuracy into:

• Technical, having an error of 15 - 60 arc seconds.
• Accurate with an error of less than 10 seconds.
• High-precision. Allow to perform measurements with an error of up to 1 arc seconds.

General device

Theodolite contains the following elements:

• Sight pipe. It has a certain magnification multiplicity. This part is fixed on two columns, which are mounted on the tribrach.
• Counting mechanisms. They include a vertical and a horizontal circle (limb). The first is in the column, and the second is in the base of the device.
• Dashed or scale microscope. This theodolite reading device is used in mechanical tools. In the first one, the count is performed according to the stroke of the index, and in the second - on the scale. The microscope is designed to read the readings from the limbs.
• Alidade. It is a swivel ruler that has a rigid connection to the limb body. Contains the counting mechanism - nonius.
• Adapter and guide screws. During tincture and alignment, these screws inform the mechanism of the device of a gentle movement.
• The center. With this built-in optical plummet, precise centering is performed above the point.
• Tripod tripod. This element is used when performing work on a specific location. Theodolite is installed on it.

How does the device work?

The mechanical theodolite works according to the following principle. The user observes the images of various points of the construction through the eyepiece of the telescope. When the sight is pointed at the observed point, in the eyepiece of the microscope, which has a dashed or scale marking, both vertical and horizontal angle is fixed. The first is the angle of inclination, and the second is the angle of the direction.

The specialist sequentially guides the pipe to the control points of the structure, measures the angles, and then writes these indicators to the log. All this is done when an optical theodolite is used. Measurements of angles made by a surveyor play an important role. They allow you to find out how well the project is performing.

When using electronic devices in the work, there is no need for visual fixation of corners. After all, the electronic sensors of the horizontal and vertical circles in automatically transmit all the data to the LCD display of the device in a familiar digital form. Also, all data is stored in the device memory. The use of electronic theodolites provides an increase in the productivity of a specialist and eliminates errors associated with improper visual reading of available indications in the case of measuring angles on an optical model.

How to work with the theodolite?

How to determine if the required point of the measuring angle was correctly recorded? All theodolites are equipped with levels. During the installation, they must be precisely set. By adjusting the screws, you can get the required level. The accuracy of the center of the limb is established by a plumb line or an optical centering device. When you learned what elements the device consists of, you can start working with the theodolite.

Installation and adjustment of the device

How to use this tool? First you need to install the device on a tripod. Then it is necessary to determine two reference points, which will be guided by the telescope of the instrument. First it is directed to the first point. Next, the instrument is fixed and measured by means of a vertical thread. Then the horizontal circle is counted. All the data must be entered in the log, then the fix is removed. Next you need to track the second point. To do this, turn the theodolite clockwise. At the next stage, turn the pipe through the zenith.

Next, you need to change the position of the circle and point the pipe at the point. If there are minor discrepancies in the measurements, then the average value will be correct. During the measurement, the limb must be zero or close to it. Rotation of the alidade should be stopped at the moment when the strokes coincide with zero values on the limb and the microscope. All the above measurements are performed in a circle.

Selecting the device

Before choosing a device, you should determine the type of work that will be performed on the theodolite. In most cases, the simplest device that has average characteristics is suitable. Usually such devices are inexpensive. When choosing a theodolite device, do not pay much attention to such parameters as data transmission and internal memory, because they do not have functional use.

Instruction manual for theodolites

A standard instruction for each theodolite is the instructions for use. The user guide describes the sequence of work performed on the device. Using this little book, you can deal with the theodolite without outside help. The user's manual is also a warranty card and technical passport of the device. The average price of a theodolite electronic is 50-70 thousand rubles.

How is theodolite arranged?

The instructions to the theodolite contain a minimum of information about the device. It includes the following data:

• The most important technical characteristics;
• Scope of application;
• Purpose buttons;
• How to properly install the tool and prepare for measurement;
• How to use the device;
• Aiming at the target;
• How to perform verification and adjustment of the instrument;
• Care of the device.

The instruction manual in paper form is compact and versatile, which is a great advantage. It does not take up much space and you can take it with you. This instruction will not freeze the LCD screen and will not charge. From it at any time you can find out the necessary information, even if you are in the field, on a construction site or career.

The instructions for the theodolite device have all the information about the instrument that will help you set up and verify.

Domestic Theodolite

Theodolite 4T30P is the most popular geodetic device of domestic production. It is manufactured by the Ural Optical-Mechanical Plant. This theodolite belongs to the category of instruments of technical accuracy. Theodolite 4t30p has the following advantages:

• Readings are taken with the help of a microscope;
• A three-time method can be used. In this case, use a removable stand with built-in optical centering;
• Contains a telescope of a direct image;
• Permutation of the limb is carried out with the rotation of the special screw of the device;
• There is a removable tribrach;
• The device can be used in different climatic regions;
• Low weight;
• Small dimensions of the device.

Theodolite is successfully used in the following areas:

• Agriculture;
• geodesy;
• Landscape design;
• geology;
• forestry.

This theodolite is often used in heavy field conditions. The price of the theodolite is approximately 50-60 thousand rubles.

Thus, the choice of theodolite is yours, which directly depends on the scope of work.