The parallel light tube measures the field of view of the optical system

The field of view of the telescopic system refers to the range of object space that can be observed by the telescopic system instrument. The field of view of the telescopic system is generally limited by the size of the plate frame (field of view diaphragm). The field of view of the telescopic system is represented by the Angle 2ω of the visible object space edge light to the incident pupil center, as shown in Figure 1-1.

Figure (1-1) Schematic diagram of the field of view of the telescopic system

Use a field of view to measure

Field of view is actually a kind of large field of view parallel light tube. Figure 1-2 shows the diagram of the field of view instrument. Its objective lens adopts a wide-angle photographic objective lens with good image quality under a large field of view, and a dividing plate is placed on the focal surface of the objective lens with a relatively large dividing edge. A cross dividing line is engraved on the dividing plate, and the dividing value of the dividing line directly marks the Angle between the engraving line and the center of the objective lens. The vertical and horizontal carvings of the cross are engraved with the scale values of two angular units. On the horizontal engraving line, the scale value of the ordinary Angle unit is engraved, that is, the degree is used, the unit is divided into, the division range is 20°, and the grid value is 6 '. On the vertical engraving line, there is the engraving line of the "mi-bit" Angle unit, which is the common Angle unit of military optical instruments, with 3 to 30 mi-bits above and below, and the grid value is 0-02 mi-bits. Figure 12-21(a) shows the scale of the middle part of the partition board. The unit of "mil-bit" Angle is 1 mil-bit, which is 1/6,000th of the circumference Angle, and is denoted as 0-01. 1 The Angle of the circumference is 6,000 mil, denoted as 60-00.

Figure (1-2) Schematic diagram of the field of view instrument

The field of view instrument also has a small field of view, such as the left and right side of the 12.5° field of view instrument. Table 2-1 lists the data of the three field of view instruments. Different Angle ranges of field of view instruments can be used according to different requirements.