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DOI: 10.22184/1993-7296.FRos.2025.19.2.142.147
Two variants of the design of a telescopic sight
with variable magnification are considered. The
first one 1–10×24 is wide field of view 10× zoom
magnification. The second one (1–4.5×20) is
compact and lightweight 150 mm long telescopic
sight. Additional attachments installed in front of
objective lens and behind of eyepiece significantly
expand the functionality of the telescopic sight
and can easily turn it into an “smart” one
Two variants of the design of a telescopic sight
with variable magnification are considered. The
first one 1–10×24 is wide field of view 10× zoom
magnification. The second one (1–4.5×20) is
compact and lightweight 150 mm long telescopic
sight. Additional attachments installed in front of
objective lens and behind of eyepiece significantly
expand the functionality of the telescopic sight
and can easily turn it into an “smart” one
Теги: smart telescopic sight thermal attachment zoom прицел с переменным увеличением телескопическая насадка телескопический прицел
Smart Telescopic Sight
I. P. Shishkin, A. P. Shkadarevich
NTC “LEMT” BeloMO, Minsk, Republic of Belarus
Two variants of the design of a telescopic sight with variable magnification are considered. The first one 1–10×24 is wide field of view 10× zoom magnification. The second one (1–4.5×20) is compact and lightweight 150 mm long telescopic sight. Additional attachments installed in front of objective lens and behind of eyepiece significantly expand the functionality of the telescopic sight and can easily turn it into an “smart” one.
Keywords: smart telescopic sight, zoom, thermal attachment
Article received: 21.09.2024
Article accepted: 26.11.2024
Introduction
Telescopic sights are constantly being improved. The magnification range and field of view of the sights are expanding, they become lighter and more compact. A new class of smart sights has appeared with a built-in rangefinder and ballistic calculator, with the function of automatically entering corrections and displaying information about weather conditions.
The Swarovski dS 5-25x52P, Steiner M7Xi IFS, DHF4-28×56 Dedal smart sights have built-in ballistic calculators and rangefinders. In the sights, the aiming point is calculated in real time using software, which is displayed in the field of view. The display shows the target range, air temperature and other necessary information. At the same time, all factors affecting the accuracy of aiming are taken into account – wind, air temperature, location.
The infrared attachment, mounted in front of the telescopic sight allows to observe using a thermal imager in the spectral range of 8…12 μm. An eyepiece attachment with a digital camera makes it possible to transfer an image to a computer monitor and take video. The built-in projection display allows you to enter the necessary information into the field of view of the telescopic sight (wind corrections, target range, temperature).
Design comparision
The optical layout of wide field of view 10× zoom magnification telescopic sight is shown in fig. 1. The upper figure shows the ray tracing in position 1×, the lower figure shows ray tracing in position for 10× magnification.
The optical layout includes a 3‑component objective lens, 4‑component relay system and an 3‑component eyepiece. In the relay system the first lens (collective) and the fourth lens (Barlow) are stationary, and the two inner lenses are moving.
The optical layout of the compact 1–4.5×20 sight is shown in fig. 2 and differs from the 1–10×24 layout. The choice of the design is primarily due to the desire to minimize the length of the sight. Reducing the of the field of view angle (FOV) and the magnification range made it possible to eliminate the Barlow lens and maintain an acceptable of the exit pupil position (more then 70 mm). The upper figure shows the ray tracing in position 1×, the lower figure shows the ray tracing in position 4.5×
The reticle in both sights is located in the first focal plane (FFP) and is located on the flat surface of the collective lens. This position of the reticle is also optimal in terms of minimum clear aperture (CA) diameter of the collective lens.
Asphere
The image curvature value in wide-angle telescopic sights is especially pronounced at low magnifications. At 1× magnification the angle of field of view in the 1–10×24 telescopic sight is 23 degrees, and in the 1–4.5×20 telescopic sight it is 18 degrees. The image quality from the center to the edge of the field of view degrades noticeably.
An effective way to reduce the image curvature is to use an aspherical lens. It is advisable to make an aspherical profile on a lens with a smaller diameter, since the cost of manufacturing depends on it. In a 1–10×24 telescopic sight, the optimal position of the aspherical surface is a Barlow lens with a diameter of 15 mm.
Fig. 3 shows a plot of the image curvature of the sight before using an aspherical lens (left) and after using aspherics (right).
As can be seen from the figure, the image curvature at the edge of the field of view in a 1–10×24 telescopic sight without an aspherical lens reached ≈5 diopter, and after applying an aspherical lens it became ≈0.5 diopter.
In the 1–4.5×20 telescopic sight, the angular field of view at 1x is significantly smaller than in the 1–10×24 telescopic sight and an aspherical eyepiece lens is used to correct the image curvature. The result of using aspherics is shown in fig. 4. The datasheet of the telescopic sights are shown in Table 1.
Thermal imaging attachment
On the fig. 5 shows the design of a thermal imaging attachment [4], which allows observation using a thermal imager in the spectral range of 8…12 um and is installed in front of the objective lens of a telescopic sight. The attachment design includes an infrared (IR) lens, microbolometer, display and eyepiece. One of the main requirements for the attachment is its weight. The focal length of the IR lens, the matrix format of the microbolometer and the display are determined depending on the required range, aperture, magnification, field of view, resolution and dimensions of the optical device. When using modern lens manufacturing technologies (aspherics, diffraction elements) and a special combination of glass materials, it is possible to minimize the number of lenses in the lens [2, 3], and in the eyepiece, for example, use only one aspherical lens with a diffractive surface.The datasheet of the thermal imaging attachment shown in Table 2.
Eyepiece attachment
An alternative solution for creating “intelligent” sights is the use of an external attachment [5], installed using an adapter on the eyepiece of the telescopic sight. The design of such an eyepiece attachment is shown in fig. 6.
The key element of the attachment is a beam-splitting plate (splitter). It helps to separate the beam of light coming out of the eyepiece of a telescopic sight: part of the light falls on the digital camera, the other into the observer’s eye. When working with the display, the light reflected from the beam-splitting layer of the plate is projected into the output pupil of the device. The attachment design should be compact and provide the required eyerelief distance (at least 60 mm).
Conclusion
The use of aspherical lenses makes it possible to significantly expand the field of view and the range of magnifications in the telescopic sights. And with the help of external attachments, the classic telescopic sight becomes “intelligent” with a wide range of additional functions.
AUTHORS
Shishkin Igor Petrovich, Cand. of Tech. Sciences; e-mail: shipoflens@mail.ru; RTC «LEMT» BelOMO, Minsk, Republic of Belarus.
ORCID ID: 0000-0002-4592-1060
Shkadarevich Alexey Petrovich, Dr. of Tech.Sciences, RTC «LEMT» BelOMO, Minsk, Republic of Belarus.
Contribution by the members
of the team of authors
The article was prepared on the basis of many years of work by all members of the team of authors. Development and research are carried out at the expense of RTC «LEMT» BELOMO.
Conflict of interest
The authors claim that they have no conflict of interest.
I. P. Shishkin, A. P. Shkadarevich
NTC “LEMT” BeloMO, Minsk, Republic of Belarus
Two variants of the design of a telescopic sight with variable magnification are considered. The first one 1–10×24 is wide field of view 10× zoom magnification. The second one (1–4.5×20) is compact and lightweight 150 mm long telescopic sight. Additional attachments installed in front of objective lens and behind of eyepiece significantly expand the functionality of the telescopic sight and can easily turn it into an “smart” one.
Keywords: smart telescopic sight, zoom, thermal attachment
Article received: 21.09.2024
Article accepted: 26.11.2024
Introduction
Telescopic sights are constantly being improved. The magnification range and field of view of the sights are expanding, they become lighter and more compact. A new class of smart sights has appeared with a built-in rangefinder and ballistic calculator, with the function of automatically entering corrections and displaying information about weather conditions.
The Swarovski dS 5-25x52P, Steiner M7Xi IFS, DHF4-28×56 Dedal smart sights have built-in ballistic calculators and rangefinders. In the sights, the aiming point is calculated in real time using software, which is displayed in the field of view. The display shows the target range, air temperature and other necessary information. At the same time, all factors affecting the accuracy of aiming are taken into account – wind, air temperature, location.
The infrared attachment, mounted in front of the telescopic sight allows to observe using a thermal imager in the spectral range of 8…12 μm. An eyepiece attachment with a digital camera makes it possible to transfer an image to a computer monitor and take video. The built-in projection display allows you to enter the necessary information into the field of view of the telescopic sight (wind corrections, target range, temperature).
Design comparision
The optical layout of wide field of view 10× zoom magnification telescopic sight is shown in fig. 1. The upper figure shows the ray tracing in position 1×, the lower figure shows ray tracing in position for 10× magnification.
The optical layout includes a 3‑component objective lens, 4‑component relay system and an 3‑component eyepiece. In the relay system the first lens (collective) and the fourth lens (Barlow) are stationary, and the two inner lenses are moving.
The optical layout of the compact 1–4.5×20 sight is shown in fig. 2 and differs from the 1–10×24 layout. The choice of the design is primarily due to the desire to minimize the length of the sight. Reducing the of the field of view angle (FOV) and the magnification range made it possible to eliminate the Barlow lens and maintain an acceptable of the exit pupil position (more then 70 mm). The upper figure shows the ray tracing in position 1×, the lower figure shows the ray tracing in position 4.5×
The reticle in both sights is located in the first focal plane (FFP) and is located on the flat surface of the collective lens. This position of the reticle is also optimal in terms of minimum clear aperture (CA) diameter of the collective lens.
Asphere
The image curvature value in wide-angle telescopic sights is especially pronounced at low magnifications. At 1× magnification the angle of field of view in the 1–10×24 telescopic sight is 23 degrees, and in the 1–4.5×20 telescopic sight it is 18 degrees. The image quality from the center to the edge of the field of view degrades noticeably.
An effective way to reduce the image curvature is to use an aspherical lens. It is advisable to make an aspherical profile on a lens with a smaller diameter, since the cost of manufacturing depends on it. In a 1–10×24 telescopic sight, the optimal position of the aspherical surface is a Barlow lens with a diameter of 15 mm.
Fig. 3 shows a plot of the image curvature of the sight before using an aspherical lens (left) and after using aspherics (right).
As can be seen from the figure, the image curvature at the edge of the field of view in a 1–10×24 telescopic sight without an aspherical lens reached ≈5 diopter, and after applying an aspherical lens it became ≈0.5 diopter.
In the 1–4.5×20 telescopic sight, the angular field of view at 1x is significantly smaller than in the 1–10×24 telescopic sight and an aspherical eyepiece lens is used to correct the image curvature. The result of using aspherics is shown in fig. 4. The datasheet of the telescopic sights are shown in Table 1.
Thermal imaging attachment
On the fig. 5 shows the design of a thermal imaging attachment [4], which allows observation using a thermal imager in the spectral range of 8…12 um and is installed in front of the objective lens of a telescopic sight. The attachment design includes an infrared (IR) lens, microbolometer, display and eyepiece. One of the main requirements for the attachment is its weight. The focal length of the IR lens, the matrix format of the microbolometer and the display are determined depending on the required range, aperture, magnification, field of view, resolution and dimensions of the optical device. When using modern lens manufacturing technologies (aspherics, diffraction elements) and a special combination of glass materials, it is possible to minimize the number of lenses in the lens [2, 3], and in the eyepiece, for example, use only one aspherical lens with a diffractive surface.The datasheet of the thermal imaging attachment shown in Table 2.
Eyepiece attachment
An alternative solution for creating “intelligent” sights is the use of an external attachment [5], installed using an adapter on the eyepiece of the telescopic sight. The design of such an eyepiece attachment is shown in fig. 6.
The key element of the attachment is a beam-splitting plate (splitter). It helps to separate the beam of light coming out of the eyepiece of a telescopic sight: part of the light falls on the digital camera, the other into the observer’s eye. When working with the display, the light reflected from the beam-splitting layer of the plate is projected into the output pupil of the device. The attachment design should be compact and provide the required eyerelief distance (at least 60 mm).
Conclusion
The use of aspherical lenses makes it possible to significantly expand the field of view and the range of magnifications in the telescopic sights. And with the help of external attachments, the classic telescopic sight becomes “intelligent” with a wide range of additional functions.
AUTHORS
Shishkin Igor Petrovich, Cand. of Tech. Sciences; e-mail: shipoflens@mail.ru; RTC «LEMT» BelOMO, Minsk, Republic of Belarus.
ORCID ID: 0000-0002-4592-1060
Shkadarevich Alexey Petrovich, Dr. of Tech.Sciences, RTC «LEMT» BelOMO, Minsk, Republic of Belarus.
Contribution by the members
of the team of authors
The article was prepared on the basis of many years of work by all members of the team of authors. Development and research are carried out at the expense of RTC «LEMT» BELOMO.
Conflict of interest
The authors claim that they have no conflict of interest.
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