WO2022057334A1

WO2022057334A1 - Method for resolving lens day/night non-confocal focus

Info

Publication number: WO2022057334A1
Application number: PCT/CN2021/099846
Authority: WO
Inventors: 陈俊宏
Original assignee: 湖北华鑫光电有限公司
Priority date: 2020-09-17
Filing date: 2021-06-11
Publication date: 2022-03-24
Also published as: CN111913282A

Abstract

Provided is a method for resolving lens day/night non-confocal focus; a lens consists of a lens group and a light filter set; the lens group at least contains one lens; the thickness of the light filter is T, and the refractive index is nd; the light filter is used for switching between day and night photo-capture, the back focal length of photo-capture being BFL, the discrepancy between back focal length during daytime and during nighttime photo-capture being σ, the amount of compensation of the light filter to satisfy the day/night confocal plane being d; d satisfying the following condition: d = σ*nd / (nd-1), wherein σ = nighttime BFL - daytime BFL; and if said nighttime BFL > daytime BFL, the thickness of the light filter during the day is to be compensated, the light filter thickness during the day becoming T+d; if the nighttime BFL < daytime BFL, the light filter thickness during the day becoming T+d. By means of compensating for the thickness of the filter switching between day and night, a day/night confocal imaging quality effect can be achieved; there is no additional cost, and the quality of processing and assembly are taken into account.

Description

A method to solve the day and night of the lens is not confocal

technical field

The invention relates to the technical field of lenses, and more particularly to a method for solving the day and night non-confocal lenses.

Background technique

In the current era of advanced information, the proportion of dependence on electronic products is increasing, which makes human beings even more inseparable from the convenience brought by electronic products, and also drives the development of the network, which is connected with life, and the photosensitive chip's The popularization has also driven the development of the optical lens industry, and at the same time, the demand for security monitoring has become increasingly popular, so that a monitor will be installed at the door of every household or at the intersection on the street to achieve the purpose of 24-hour security monitoring. However, the wavelengths of light used in daytime monitoring and nighttime monitoring are different, which will result in a non-confocal situation during day and night, which makes the image blurred when shooting at night.

In order to solve the above problems, in the optical design stage, it is necessary to compensate the lens structure to reduce the minimum back focus (BFL) offset when switching between day and night, so as to ensure the quality of shooting at night. However, this often increases the difficulty of design, and selects more expensive materials for design, and also increases the difficulty of lens assembly or processing, reduces the yield of production, and greatly increases the cost.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a method for solving the non-confocal day and night of the lens, which only needs to do some thickness compensation on the filter that is switched between day and night to achieve the imaging quality effect of day and night confocal, and the cost is not high. Need to increase, but also to ensure quality.

To achieve the above object, the present invention provides the following technical solutions:

A method for solving the non-confocal day and night of a lens, the lens is composed of a lens group and an optical filter; it is characterized in that, the lens group comprises at least one lens; the thickness of the optical filter is T, and the refractive index is nd; The filter is used for switching between day and night shooting, the back focus of shooting is BFL, the amount of back focus difference between daytime and night shooting is σ, and the compensation amount of the filter to meet the day and night confocal plane is d; the d The following conditions are met: d=σ*nd/(nd-1); wherein, the σ=BFL at night-BFL during the day; and when the BFL at night > BFL during the day, the filter for the daytime should be adjusted The thickness is compensated, and the filter thickness during daytime becomes T+d; when the nighttime BFL<daytime BFL, the daytime filter thickness becomes Td.

Preferably, in the above-mentioned method for solving the day and night non-confocal lens, the lens is composed of an aperture, a first lens, and a filter; the first lens is a plastic aspheric surface.

Preferably, in the above method for solving the day and night non-confocal lens, the lens is composed of a first lens, an aperture, a second lens and a filter; the first lens and the second lens are glass aspheric surfaces.

Preferably, in the above-mentioned method for solving the day and night non-confocal lens, the lens is composed of a first lens, an aperture, a second lens, a third lens and a filter; the first lens, the second lens, The third lens is a plastic aspheric surface.

It can be seen from the above technical solutions that, compared with the prior art, the lens structure of the present invention can achieve the imaging quality effect of day and night confocal by performing thickness compensation on the day and night switching filter, and the cost does not need to be increased. , and at the same time can take into account the quality of processing and assembly.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the provided drawings without creative work.

FIG. 1 is a ray tracing diagram during daytime according to the first embodiment of the present invention.

FIG. 2 is a ray tracing diagram at night according to the first embodiment of the present invention.

FIG. 3 is a ray tracing diagram during daytime according to the second embodiment of the present invention.

FIG. 4 is a ray tracing diagram at night according to the second embodiment of the present invention.

FIG. 5 is a ray tracing diagram in daytime of the third embodiment of the present invention.

FIG. 6 is a ray tracing diagram at night according to the third embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The first embodiment: a method for solving the day and night non-confocal lens, the lens is composed of an aperture, a first lens group and a filter; the thickness of the filter is T, and the refractive index is nd; the filter is The film is used for the switching of day and night shooting, the back focus of shooting is BFL, the amount of back focus difference between daytime and night shooting is σ, and the compensation amount of the filter to meet the day and night confocal plane is d; the d meets the following conditions: d=σ*nd/(nd-1). The daytime BFL of this lens meets the conditions as shown in Table 1:

Table I

The BFL of this lens at night meets the conditions as shown in Table 2:

Table II

In this embodiment: the amount of back focus difference between daytime and nighttime σ=3.85688-3.76714=0.08974 Filter compensation d=0.08974*1.523/(1.523-1)=0.2613; so the thickness of the white light filter needs to be changed to T+ d=0.3+0.26133=0.56133, the lens parameters after white light filter compensation are shown in Table 3, the white light and red light (850nm) BFL after compensation filter are basically the same (see Figure 1-2).

Table 3

Second embodiment:

A method for solving the day and night non-confocal of a lens, the lens is composed of an aperture, a first lens group, a second lens group and a filter; the thickness of the filter is T, and the refractive index is nd; the filter The film is used for the switching of day and night shooting, the back focus of shooting is BFL, the amount of back focus difference between daytime and night shooting is σ, and the compensation amount of the filter to meet the day and night confocal plane is d; the d meets the following conditions: d=σ*nd/(nd-1).

The daytime BFL of this lens satisfies the conditions as shown in Table 4.

Table 4

The BFL of this lens at night meets the conditions as shown in Table 5:

Table 5

In this embodiment: the amount of back focus difference between daytime and nighttime σ=1.5758–1.5568=0.019 Filter compensation d=0.019*1.523/(1.523-1)=0.0553; so the thickness of the filter for white light needs to be changed to T+d= 0.7+0.0553=0.7553, the lens parameters after white light filter compensation are shown in Table 6, the white light and red light (850nm) BFL after compensation filter are basically the same (see Figure 3-4).

Table 6

Third embodiment:

A method for solving the non-confocal day and night of a lens, the lens is composed of an aperture, a first lens group, a second lens group, a third lens group and a filter; the thickness of the filter is T, and the refractive index is nd ; The filter is used for switching between day and night shooting, the back focus of shooting is BFL, the amount of back focus difference between daytime and night shooting is σ, and the compensation amount of the filter to meet the day and night confocal plane is d; the d satisfies the following conditions: d=σ*nd/(nd-1). The daytime BFL of this lens satisfies the conditions as shown in Table 7.

Table 7

The BFL of this lens at night meets the conditions as shown in Table 8:

Table 8

In this embodiment: the amount of back focus difference between daytime and nighttime σ=1.201–1.18086=0.02014 Filter compensation d=0.02014*1.523/(1.523-1)=0.05865; therefore, the thickness of the filter for white light needs to be changed to T+d= 0.7+0.05865=0.75865, the lens parameters after white light filter compensation are shown in Table 9, the white light and red light (850nm) BFL after compensation filter are basically the same (see Figure 5-6).

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant part can be referred to the description of the method.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

A method for solving the non-confocal day and night of a lens, the lens is composed of a lens group and an optical filter; it is characterized in that, the lens group comprises at least one lens; the thickness of the optical filter is T, and the refractive index is nd; The filter is used for switching between day and night shooting, the back focus of shooting is BFL, the amount of back focus difference between daytime and night shooting is σ, and the compensation amount of the filter to meet the day and night confocal plane is d; the d The following conditions are met: d=σ*nd/(nd-1); wherein, the σ=BFL at night-BFL during the day; and when the BFL at night > BFL during the day, the filter for the daytime should be adjusted The thickness is compensated, and the filter thickness during daytime becomes T+d; when the nighttime BFL<daytime BFL, the daytime filter thickness becomes Td.
The method for solving the non-confocal day and night of a lens according to claim 1, wherein the lens is composed of an aperture, a first lens and a filter; and the first lens is a plastic aspheric surface.
The method for solving the day and night non-confocal lens of a lens according to claim 1, wherein the lens is composed of a first lens, an aperture, a second lens and a filter; the first lens and the second lens It is a glass aspheric surface.
The method for solving the day and night non-confocal lens of a lens according to claim 1, wherein the lens is composed of a first lens, an aperture, a second lens, a third lens and a filter; the first lens , The second lens and the third lens are plastic aspheric surfaces.