CN104656174A - Subwavelength photon sieve fly-eye - Google Patents

Abstract

The invention relates to an optical imaging device, and specifically relates to a subwavelength photon sieve fly-eye. The subwavelength photon sieve fly-eye comprises an incident light source, M subwavelength photon sieves, a metal layer, a substrate and a focal plane, wherein the substrate forms a hemispheroid, the metal layer is attached to the outside of the substrate, the focal plane is located in the sphere center of the hemispheroid, the M subwavelength photon sieves are distributed on the metal layer, incident light of the incident light source is vertically incident from each subwavelength photon sieve, and the incident light is simultaneously focused on the focal plane. The subwavelength photon sieve fly-eye provided by the invention has high resolution, can improve the energy utilization and expand the sensitivity range, and a promotion effect on the functionization of the fly-eye in the fields of high resolution microscopes, lightweight astronomical telescopes, weapons sights, and the like is achieved, and therefore, the fly-eye has a wide application prospect.

Description

Sub-wavelength photon screen compound eye

Technical field

The present invention relates to a kind of optical imaging device, be specially sub-wavelength photon screen compound eye.

Background technology

Calendar year 2001, German L.Kipp professor publishes an article on Nature periodical, proposes photon sieves concept first, rear by translations " photon screen ".Photon screen is a kind of novel diffraction optics image device, and it replaces the printing opacity endless belt of Fresnel structure to be formed with the aperture be randomly dispersed on printing opacity endless belt, and hole diameter is greater than corresponding light penetrating ring bandwidth, and focusing can measure positive impact.Through optimal design, it can effectively suppress secondary and Advanced Diffraction, thus improves contrast and the resolving power of imaging, and even can break traditions the diffraction imaging limit, realizes super-resolution imaging.

But, the aperture focusing be only distributed on printing opacity endless belt can measure positive impact, and other region, existence as the region on light tight endless belt, printing opacity endless belt between aperture etc. will weaken focus energy, produce negative influence, thus causing the sharply decline of diffraction efficiency or capacity usage ratio, most energy of light source are wasted.According to foreign literature report and theoretical analysis, even if completely ideally, the capacity usage ratio of plain edition photon screen also only about 10%, this is that it is difficult to practical fatal part.

In order to overcome this problem, Chinese scholars proposes multi-wavelength photon screen and mixed type photon sieve structure.As: 1) people such as Univ Florida USA Chung devises dual wavelength and multi-wavelength photon screen, traditional photon screen is carried out region segmentation, the corresponding wavelength in each region, weaken the wavelength sensitivity of photon screen to incident light, but due to the segmentation in region, make the photon screen further off-energy that capacity usage ratio is natively very low.Meanwhile, because the structure of photon screen in zones of different is different, no small difficulty is brought to manufacturing process; 2) Chinese Academy of Sciences Microelectronics Institute thank to evergreen seminar, the Hu Song seminar of Photoelectric Technology Inst., Chinese Academy of Sciences, Deng proposition mixed type photon screen, combine the structure of Fresnel zone plate and photon screen, only on partial light permeability endless belt, design printing opacity aperture, the printing opacity aperture and not all light penetrating ring band all distributes, through optimal design, this structure improves capacity usage ratio to a certain extent, but and not obvious.

Existing photon sieve structure is difficult to increase substantially capacity usage ratio, how to design a kind of novel photon sieve structure, while reservation high resolution, also there is the advantages such as the high and photosensitive angular region of capacity usage ratio is wide, become the key issue that industry is badly in need of solution.

Summary of the invention

For above-mentioned technical matters, the invention provides a kind of sub-wavelength photon screen compound eye structural, while reservation high resolution, also have the advantages such as the high and photosensitive angular region of capacity usage ratio is wide, concrete technical scheme is:

Sub-wavelength photon screen compound eye, comprises incident light source, M sub-wavelength photon screen, metal level, substrate, focal plane; Described substrate forms a hemisphere, described substrate is outward with metal level, described focal plane is positioned at the hemispheroidal centre of sphere of substrate, M described sub-wavelength photon screen distribution on the metal layer, the incident ray of described incident light source is respectively from each sub-wavelength photon screen vertical incidence, and incident ray is focused on focal plane simultaneously.

Each sub-wavelength photon screen is equivalent to an ommatidium, and M sub-wavelength photon screen forms a compound eye structural.

Angle between adjacent sub-wavelength photon screen incident ray is for being followed successively by θ ₁, θ ₂..., θ _m-1, the incident ray scope that sub-wavelength photon screen compound eye accepts is θ=θ ₁+ θ ₂+ ... + θ _m-1.Angle between adjacent sub-wavelength photon screen incident ray can set according to actual needs, can get equal angular, also can get different angles, but each other can not be overlapping.

Region between adjacent sub-wavelength photon screen is lighttight, therefore under the nonoverlapping prerequisite of the adjacent sub-wavelength photon screen of guarantee, between adjacent sub-wavelength photon screen, gap should be little as far as possible.

The incident light source that all sub-wavelength photon screens adopt is co-wavelength light source, realizes by simple geometrical light-path.

Sub-wavelength photon screen is made up of a series of printing opacity aperture, the distribution of sub-wavelength photon screen on the metal layer, metal level is plated on substrate, metal layer thickness is about tens microns, sub-wavelength photon screen is close on the sphere of substrate and metal level formation, approximate tangent with sphere, the focal length of spherical radius and sub-wavelength photon screen.Metal layer material is light-proof material, is generally chromium, gold, aluminium, copper etc.; Backing material is light transmissive material, is generally common quartz glass, organic glass, fused quartz etc.

The structural parameters of sub-wavelength photon screen through optimization method are:

(1) according to design needs, the hemispheroidal spherical radius of sub-wavelength photon screen compound eye size and substrate place is determined, the focal distance f of spherical radius and sub-wavelength photon screen;

(2) according to the principle do not overlapped each other between adjacent sub-wavelength photon screen, quantity M and the entrance pupil bore D of sub-wavelength photon screen is determined;

(3) by designed central wavelength λ, entrance pupil bore D, focal distance f, determine sub-wavelength photon sieve structure parameter, calculate sub-wavelength photon screen endless belt number N:

$N\≈\frac{D^2}{4\mathrm{\λf}}$

Select suitable window function, optimize quantity and the pore size of printing opacity aperture of determining each endless belt of sub-wavelength photon screen distributes.

Sub-wavelength photon screen compound eye provided by the invention, by the inspiration of compound eye insect visual system, the vision system of compound eye insect is made up of multiple independently ommatidium, ten thousand not etc. from several to several for quantity, the independent photosensitive and imaging of each ommatidium, drastically increase sensitive volume, even can three-dimensional imaging, as: fly, dragonfly etc.Be similar to Compound Eye of Insects, the sub-wavelength photon screen compound eye of the present invention's design, both there is high resolution, capacity usage ratio can be improved again, expand sensitive volume, it is played a driving role in the practical of field such as high resolution microscope, lightweight astronomical telescope, weapon visions, is with a wide range of applications.

Accompanying drawing explanation

Fig. 1 is structural representation of the present invention;

Fig. 2 is photon screen compound eye and common photon screen Performance comparision.

Embodiment

Accompanying drawings the specific embodiment of the present invention, as shown in Figure 1: sub-wavelength photon screen compound eye, comprises incident light source 1, a M sub-wavelength photon screen 2, metal level 3, substrate 4, focal plane 5; Described substrate 4 forms a hemisphere, described substrate 4 is outer with metal level 3, described focal plane 5 is positioned at the hemispheroidal centre of sphere of substrate 4, M described sub-wavelength photon screen 2 is distributed on metal level 3, the incident ray of described incident light source 1 is respectively from each sub-wavelength photon screen 2 vertical incidence, and incident ray is focused on focal plane 5 simultaneously.

The designing requirement of this embodiment is: compound eye is semi-spherical shape, radius of a ball r=200mm, the quantity M=5 of sub-wavelength photon screen 2, and the angle between adjacent sub-wavelength photon screen 2 incident ray gets identical numerical value, θ ₀=θ ₁=θ ₂=θ ₃=θ ₄=θ ₅=30 °, the angular range, theta=θ of light can be accepted ₁+ θ ₂+ θ ₃+ θ ₄=120 °.

Substrate 4 light transmissive material is quartz glass, and metal level 3 material is chromium;

The parameter of sub-wavelength photon screen is: designed central wavelength λ=635nm, focal distance f=200mm, entrance pupil bore D=50mm;

By designed central wavelength λ, entrance pupil bore D, focal distance f, determine sub-wavelength photon screen 2 structural parameters, calculate sub-wavelength photon screen endless belt number N:

$N\≈\frac{D^2}{4\mathrm{\λf}}$

Connes window function is selected to optimize quantity and the pore size of printing opacity aperture on each endless belt.

In order to carry out detailed comparative analysis to the focusing performance of sub-wavelength photon screen compound eye and common photon screen and capacity usage ratio, Fig. 2 is the normalized distribution of radial light intensity on focal plane, the common photon screen of represented by dotted arrows, solid line represents photon screen compound eye, ordinate is normalized intensity, dimensionless, horizontal ordinate is radial distance, and unit is μm.As can be seen from Figure 2, the focusing performance of photon screen compound eye and common photon screen there is no obvious difference, but the normalized intensity of photon screen compound eye is obviously greater than common photon screen, this is because photon screen compound eye has widened photosensitive angular region, the incident light of greater angle scope can be accepted, superpose the energy of 5 sub-eyes, improve capacity usage ratio.

Claims (1)

1. sub-wavelength photon screen compound eye, is characterized in that: comprise incident light source (1), a M sub-wavelength photon screen (2), metal level (3), substrate (4), focal plane (5); Described substrate (4) forms a hemisphere, described substrate (4) is outward with metal level (3), described focal plane (5) is positioned at substrate (4) the hemispheroidal centre of sphere, M described sub-wavelength photon screen (2) is distributed on metal level (3), the incident ray of described incident light source (1) is respectively from each sub-wavelength photon screen (2) vertical incidence, and incident ray is focused on focal plane (5) simultaneously.