RU183840U1 - Sunshade hood - Google Patents

Abstract

The invention relates to optical devices, in particular to the construction of blends, and can be used to prevent lateral light from entering the objective of the optical device. The lightproof hood contains a housing with diaphragms. In this case, the diaphragms are made on the inner cone-shaped surface of the body in the form of a set of identical grooves arranged at a constant pitch, forming repeating triangles with a diffusely reflective black coating. Moreover, the vertices of the triangles are located on the border of the field of view. The inner side of the triangle facing the lens is perpendicular to the optical axis of sight, and the angle of the outer side of the triangle relative to the optical axis of sight is greater than the angle between the boundary of the field of view and the optical axis of sight. The technical result is a simplification of the design of the sunshade hood. 3 ill.

Description

The invention relates to optical devices, in particular to the construction of blends, and can be used to prevent lateral light from entering the objective of the optical device.

The optical hood is known from the prior art (Yu.G. Yakushenkov, VN Lukantsev, MP Kolosov “Methods for combating interference in optoelectronic devices”, Moscow, “Radio and communications” 1981, p. 118, fig. . 6.3), consisting of a body and a set of flat internal diaphragms mounted perpendicular to the longitudinal axis of the hood.

The disadvantage of this optical lens hood is that for a given attenuation coefficient of the lens hood it has large dimensions along the length and a significant number of diaphragms.

Known protective hood for optical devices of circular type (RF patent No. 2397523, published 08/20/2010, IPC: G03B 11/04,), the internal volume of which contains a gas or a mixture of gases under pressure not lower than the ambient pressure, and the housing , diaphragms and an optically transparent layer with a selective transmittance (absorption) of light are made of materials chemically resistant to vapors and aqueous solutions of alkalis and acids, including hydrofluoric (hydrofluoric) acid.

The disadvantages of this hood are low performance due to the inability to control the angle of view, as well as the inability to ensure stability of the transmittance of light when used in environments with a high aerosol content.

Closest to the proposed one is a sunshade hood for optical devices (Patent RU No. 2073903, published 02.20.1997, IPC: G03B 11/04), which is selected as a prototype. The lightproof hood for optical instruments consists of a housing and diaphragms. Moreover, each diaphragm is made in the form of a lateral surface of a truncated cone, the generatrix of which makes an angle in the range of 80 ° -110 ° for each diaphragm with its limit beam, its working edge being at the boundary of the field of view of the optical device. The working edge of each previous diaphragm, counting from the inlet of the hood, lies on the segment formed by the working edge of the subsequent diaphragm and the point of intersection of the field of view of the optical device with a straight line that connects the attachment point of the subsequent diaphragm to the hood body with the entry point of the light rays.

The technical problem solved by the creation of the claimed utility model is the complexity of the construction of the hood and the complexity of the technology for its manufacture, due to the presence of several separate diaphragms installed inside the hood of the hood light-shielding.

The technical result of the claimed utility model is to create a simplified design of the lens hood with increased reliability of its elements.

This technical result is achieved by the fact that the lens hood includes a housing with diaphragms. At the same time, it differs from the prototype in that the diaphragms are made on the inner conical surface of the body in the form of a set of identical grooves placed at a constant pitch, forming repeating triangles with a black diffusion reflective coating. Moreover, the vertices of the triangles are located on the border of the field of view. The inner side of the triangle facing the lens is perpendicular to the optical axis of sight, and the angle of the outer side of the triangle relative to the optical axis of sight is greater than the angle between the boundary of the field of view and the optical axis of sight.

The essence of the utility model is illustrated in the figure, which presents the following elements:

1 - housing

2 - aperture

3 - the inner surface of the housing,

4 - the top of the triangle of the diaphragm,

5 - the outer side of the triangle of the diaphragm,

6 - the inner side of the triangle diaphragm,

7 - the entrance pupil of the lens,

8 - the lens of the optoelectronic device (OEP),

9 - optical axis of sight of the EIA.

During the operation of optoelectronic devices (OED), interference of various nature often occurs, the fight against which is one of the main tasks that are solved in the process of extracting useful information. One of the known means of protecting EIA from lateral interference is light-protective hoods designed to reduce the brightness of the scattered light to a value lower than the brightness of background noise, as well as to suppress possible glare from lateral interference. The proposed lens hood (Fig. 1) contains a cone-shaped body 1 with diaphragms 2. Moreover, the diaphragms 2 are made on the inner conical surface 3 of the housing 1. The diaphragms 2 are formed by a set of identical grooved grooves made with a constant step t. The profile of the diaphragms 2 is in the form of repeating triangles having a black diffusion reflective coating. The vertices of the triangles 4 of the diaphragm 2 are located on the border of the field of view. The inner sides of the triangles 5 (leg) of the diaphragm 2 facing the lens 8 are perpendicular to the optical axis of sight 9, and the angle α of the outer sides of the triangles 6 (hypotenuse) of the diaphragm 2 relative to the optical axis of sight 9 is larger than the angle β between the boundary of the field of view and the optical axis of sight 9 The angle γ at the apex of triangle 4 of the diaphragm 2 depends on the dimensions of the light-protective hood and the technology for its manufacture. The most technologically optimal optimal angle size γ = 40 ° -42 ° was experimentally established.

The main dimensions of the blend are the diameter of the input window, the diameter of the output window and its length. Dimensional parameters are determined by geometric constructions, depending on a given illumination angle α of the light-shielding hood.

The attenuation of light noise in this lens hood is as follows.

A light-protective hood is installed in front of the entrance pupil 7 of the lens of the optoelectronic device 8, coaxially with its optical axis of sight 9. Light from the side light source, passing through the entrance window of the light-shielding hood, enters the inner surface of one of the diaphragms 2 with a black matte finish. Rays having an angle of incidence greater than the limiting angle of illumination α, formed by a beam passing through the extreme points of the profiles of the first and last diaphragms 2 with the optical axis of sight 9 of the optical device, fall on the outer side (hypotenuse) of triangle 5 of one of the diaphragms 2, partially absorbed by the matte black surface, are reflected and, crossing the optical axis of sight 9, go outside, or to the surface of one of the previous diaphragms 2, which is closer to the inlet of the lens hood, shielding, losing its energy after reflection tions.

In the tables of FIG. 2 and FIG. Figure 3 shows the data for two lens hoods made for video cameras with different fields of view. For a given illumination angle α, which should not exceed 28 °, the overall dimensions of the blends were determined graphically for a video camera with a smaller field of view and a video camera with a large field of view having different angles of field of view β. The angle γ at the apex of triangle 4 of the diaphragm 2 is chosen for the blends of both cameras the same, equal to 40 °, which is the most technologically advanced in the manufacture of blends with the diaphragms of the proposed design. The diaphragms are made with a constant pitch, which is 0.5 mm and is the most optimal for light-protective hoods with the indicated dimensions.

The proposed design of the light-shielding hood is simple, does not require special technologies in the manufacture, which reduces the complexity and reliability of the hood due to the fact that the diaphragms have a simple and reliable design.

Claims (1)

A light-protective hood containing a housing with diaphragms, characterized in that the diaphragms are made on the inner conical surface of the housing in the form of a set of identical grooves placed at a constant pitch, forming repeating triangles with a black diffusion reflective coating, while the vertices of the triangles are located on the border of the field of view, inner the side of the triangle facing the lens is perpendicular to the optical axis of sight, and the angle of the outer side of the triangle relative to the optical axis is sighted a larger angle between the boundary of the field of view and the optical axis of sight.

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