RU2370798C2 - Night vision device - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: night vision device has an objective, an electro-optical converter (EOC) and an ocular system (OS). The objective is in form of four components, the first of which is a positive convex-concave lens, the second - a group of two negative lenses, the third - a positive biconvex lens, the fourth - a group of three lenses, the first of which is a positive biconvex lens, the second - a negative biconcave lens, and the third - a positive convex-concave lens. The second component can be moved relative the photocathode of the electro-optical converter to provide for smooth variation of the equivalent focal length of the objective from the minimum to the maximum value without changing position of the plane of the best installation relative the photocathode of the electro-optical converter. The fourth component can be moved relative the photocathode of the electro-optical converter so as to compensate shift of the plane of best installation at intermediate positions of the second component, where the maximum value of its displacement Δd11_max≤5S_max, where ΔS_max - is the maximum value of longitudinal spherical aberration in the working spectral range, and its additional displacement determines the near focal length.

EFFECT: possibility of usage when making night vision devices in very diverse operating conditions.

1 dwg

Description

The invention relates to the field of optoelectronic technology and can be used in the manufacture of night vision devices (night vision devices) with electron-optical converters (EOP) in a wide variety of operating conditions.

Known night vision device (patent RU No. 2182718, class G02B 23/12, publ. 05/20/2002), containing a lens, a biplanar image intensifier tube of a direct image, a corrector, a wrapping system (OS) and an eyepiece.

The closest in technical essence is a night-vision device with variable magnification, containing optically coupled lens, image intensifier tubes and an eyepiece (V.V. Tarasov, Yu.G. Yakushenkov “Infrared systems of the“ looking ”type. - Moscow: Logos, 2004 ., p. 125, Fig. 6.13). The eyepiece is pancratic and made according to patent RU 2136028, class. G02B 25/00, publ. 06/20/1997

The disadvantage of these devices is a small increase and its fixed value, which does not allow the recognition of an object after its detection during observation, and with the use of a panoramic eyepiece, the resolution of the NVD cannot exceed the value limited by the resolution of the image intensifier and the focal length of the lens used.

The present invention is the creation of NVD with a smooth change in magnification and, accordingly, with a smooth change in resolution with simple technological solutions.

The technical result due to the task is achieved by the fact that in the night vision device containing the lens, image intensifier tube and the ocular system, the lens is made in the form of four components, the first of which is a positive convex-concave lens, the second is a group of two negative lenses, the third is a positive biconvex lens, the fourth is a group of three lenses, the first of which is a positive biconvex lens, the second is a negative biconcave lens, and the third is a positive convex-concave lens. The second component has the ability to move relative to the photocathode of the image intensifier tube, while its extreme positions provide the minimum and maximum values of the equivalent focal length of the lens with the same plane of the best setting relative to the photocathode of the image intensifier tube. The fourth component has the ability to move relative to the photocathode of the image intensifier tube to compensate for the shift of the plane of the best installation at intermediate positions of the second component (at intermediate values of the equivalent focal length of the lens), while its maximum movement

Δd11 _max ≤5ΔS _max ,

where ΔS _max is the maximum value of the longitudinal spherical aberration in the working spectral range.

The movement of the fourth component also provides focusing of the device neither near distance.

The proposed device design and, above all, the separate movement of the lens components allow you to smoothly change the magnification of the system as a whole from minimum to maximum values by moving only one component, while additional small focusing by the other moving component is required only when the device is operating at intermediate magnifications (or equivalent focal length) distances), excluding extreme. In addition, moving the second movable component also ensures that the device focuses at close range. Such separate movement of the components of the lens reduces the complexity of manufacturing and assembly and eliminates the need for non-linear laws of motion of the components.

The drawing shows a diagram of NVD.

The night vision device contains a lens 1 ÷ 8, an electron-optical transducer 9, an eyepiece system 10, wherein the lens consists of a positive biconcave lens 1, two negative lenses 2 and 3, a positive biconvex lens 4, a positive biconvex lens 5, a negative biconcave lens 6 , aperture diaphragm (BP) 7 and a positive convex-concave lens 8.

In the lens, lenses 2 and 3 form a group 11 that can move relative to the photocathode of the image intensifier tube, and lenses 5, 6 and 8 with an aperture diaphragm 7 form group 12 with the ability to move relative to the photocathode of the image intensifier tube. The design parameters of the embodiment of the optical system of the lens are as follows:

Radii Thickness Glass mark Diameters R1 = 59.57 58 d1 = 7.5 STK3 R2 = 157.04 57 d2 = 8 ÷ 45 (variable) R3 = -113.18 32 d3 = 2.5 TF10 R4 = plane 31 d4 = 2.35 R5 = -57.33 31 d5 = 2.5 K8 R6 = 171.4 32 d6 = 39 ÷ 2 (variable) R7 = 77.11 32 d7 = 6 K8 R8 = -77.11 32 d8 = 17 (focus) R9 = 31.77 24 d9 = 6 STK3 R10 = -70.15 24 d10 = 1 R11 = -52.36 23 d11 = 2 TF10 R12 = 115.08 22 d12 = 11 R13 = 37.22 20.6 d13 = 4 STK3 R12 = 438.5 20,4 d14 = 22 (focus) R13 = plane 17.5 d15 = 1.2 (Photocathode of the image intensifier tube) R13 = plane 17.5

Parameters of the embodiment of the optical system of the lens:

calculated wavelength, nm 700 working spectral range, nm 486 ÷ 900 maximum longitudinal spherical aberration in the worker spectral range, ΔS _max 0.227 focal length range lens, Fekv, mm from 31.5 to 63.5 relative aperture (constant) 1: 1,5 linear field of view (constant), mm 17.5 diameter of aperture diaphragm (HELL), mm twenty removal of blood pressure from the lens 6 mm 2

The dependences of Feq on the values of d2 and d6 are as follows:

Feq d2 d6 min 31.5 8.0 39.0 average 45.3 27.5 19.5 Max 63.5 45.0 2.0

The principle of operation of the night vision device is as follows. The lens 1 ÷ 8 forms an image of objects on the photocathode of the image intensifier tube 9. The image intensifier 9 amplifies and transfers this image to its own screen, and the eyepiece system 10 allows you to view the image on the screen of the image intensifier tube 9.

When moving a group of lenses 11 relative to the photocathode of the image intensifier tube 9 from one extreme position to another, the equivalent focal length of the optical system of the lens changes from the minimum to the maximum with a constant linear field of view and, accordingly, the total increase in NVD, its angular field of view, and resolution change. At intermediate positions of the lenses 11, a defocusing of the image occurs, which is compensated by the movement of the group of lenses 12, while the maximum amount of movement to compensate for this defocusing

Δd11 _max ≤5ΔS _max .

Moving the group of lenses 12 also provides focusing of the device at close range.

Setting the quality criterion - the value of the polychromatic contrast transfer coefficient (CPC) and taking into account the spectral efficiency at wavelengths - 0.6 at a wavelength of 486 nm, 1 at 700 nm, 0.2 at 900 nm (taking into account the sensitivity of the image intensifier tube and light transmission of the optical system lens), we obtain the following calculated values in the plane of the best setting:

- for Fekv = 31.5 mm:

point on the axis: PDA = 80%

field point 12 mm:

PDA calculated for the meridional plane,

KPK _m = 34%

PDA

calculated for the sagittal plane,

PDA _with = 9%

- for Fekv = 63.5 mm:

point on the axis: PDA = 77%

field point 12 mm:

PDA _m = 10%

PDA _with = 1%

- for Fred = 45.3 mm (the shift of the lens group 12 for out-of-focus is Δd11 = -0.75 mm):

point on the axis: PDA = 70%

field point 12 mm:

- PDA _m = 12%

- PDA _with = 17%

As can be seen from the calculations, the optical system of the lens provides an acceptable image quality for the night vision device when the magnification changes by moving only one component, while it remains possible to provide intermediate magnification values with low focusing by the other component, the movement of which also ensures the device focuses at a short distance. Separate movement of the components of the lens reduces the complexity of manufacturing and assembly and eliminates the need for non-linear laws of motion of the components.

Claims (1)

A night vision device containing a lens, an electron-optical converter (EOP), an ocular system (OS), characterized in that the lens is made in the form of four components, the first of which is a positive convex-concave lens, the second is a group of two negative lens, the third is a positive biconvex lens, the fourth is a group of three lenses, the first of which is a positive biconvex lens, the second is a negative biconcave lens, the third is a positive convex-concave lens, while the second one the component has the ability to move relative to the photocathode of the image intensifier tube to ensure a smooth change in the equivalent focal length of the lens from the minimum and maximum values at a constant position of the plane of the best installation relative to the photocathode of the image intensifier tube, and the fourth component has the ability to move relative to the photocathode of the image intensifier tube to compensate for the shift of the plane of the best installation at intermediate positions of the second component (at intermediate values of the equivalent focal length of the lens), while the maximum value of its movement:
Δd11 _max ≤5ΔS _max ,
where ΔS _max is the maximum value of the longitudinal spherical aberration in the working spectral range,
and its additional movement determines the close focusing distance.

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