CN106168711A - A kind of axicon lens ring type laser irradiating device - Google Patents

Abstract

The present invention provides a kind of axicon lens ring type laser irradiating device, it includes coaxial the first plano-convex axicon lens being placed in parallel and the second plano-convex axicon lens, described first plano-convex axicon lens is identical with the refractive index of described second plano-convex axicon lens, the conical surface of described first plano-convex axicon lens is identical with the conical surface direction of described second plano-convex axicon lens, the base angle of described first plano-convex axicon lens is less than the base angle of described second plano-convex axicon lens, and the base angle of described first plano-convex axicon lens and the second plano-convex axicon lens is respectively less than 5 °.Compared with the prior art, the beneficial effects of the present invention is: a kind of axicon lens ring type laser irradiating device that the present invention provides solves and needs by repeatedly moving into, remove axicon lens to realize the drawback of 0 side-play amount in prior art, it is to avoid the irradiation non-uniformity caused due to resetting.

Description

A kind of axicon lens ring type laser irradiating device

Technical field

The present invention relates to material internal component detecting devices field, be specifically related to a kind of axicon lens ring type laser irradiation dress Put.

Background technology

Spatial deviation Raman spectroscopy (SORS) is the novel spectral measurement methods of the one occurred in recent years, draws with tradition Graceful spectral technique is compared, and in its spectral collection system, the focus of collecting lens and the focus of incident laser spatially have a spacing From skew.Due to (diffusely scattering media) on laser light incident to sample, the laser intensity of sample interior can be with the incident degree of depth Increasing and exponential decay, produced a part of scattered light will arrive sample Deep composition, return again to sample after Multiple Scattering Product surface.Therefore, on sample surfaces, create in various degree at position and the exciting light incidence point that scattered light returns is inclined Move.If scattered light is collected at certain deviation post, i.e. can obtain carrying measured matter component inside structural information Raman light.In SORS technology, Raman signal excites-particularity of collection structure so that it is and there is well suppression top layer composition and draw The graceful ability with fluorescence spectrum, is particularly well-suited to the extraction of subgrade composition Raman spectrum under non-transparent material, and then realizes thing Quick, the Nondestructive Identification of matter composition.Have been used for powder, colloid, polymer and medicine detection at present, cultural heritage is identified, disease In the research of the aspects such as diagnosis, contraband safety check and application, application prospect is the most wide.

In actual application, the key issue that SORS technology need to solve is to improve detectivity, i.e. increase investigation depth and Improve the signal to noise ratio measuring signal, and the laser radiation mode used determines it and is applied to laser power on testing sample Size, and then have influence on laser and the depth of interaction of sample, the intensity inspiring Raman signal and signal to noise ratio thereof.The U.S. M.V.Schulmerich uses axicon lens and battery of lens box-like irradiation structure, overcomes the point that the SORS technical research initial stage uses The drawback that in formula irradiation structure, laser energy is not enough, enhances the laser power being applied on testing sample, makes that collects to draw Graceful signal strengthens；The irradiation structure of Britain's rd's A Pu Islington laboratory more simplifies, and its optical element is only a piece of cone Lens.Said two devices all achieves side-play amount on two-dimensional space from 0 continuously adjustabe started, but still suffers from certain deficiency: non-zero sky Between changing of side-play amount realized by axicon lens movement on optical path direction, and when the spectrum of 0 side-play amount is measured, Optical element need to be removed from light path.The most repeatedly it is movable into and out, easily causes the difference of translation stage resetting, increase The unstability of system.

In view of drawbacks described above, creator of the present invention obtains the present invention finally through research for a long time and practice.

Summary of the invention

For solving above-mentioned technological deficiency, the technical solution used in the present invention is, it is provided that a kind of axicon lens ring type laser spoke According to device, when it is applied to spatial deviation Raman spectrum measurement system, it is not necessary to being removed by axicon lens just can be real in light path The spectral measurement of existing 0 side-play amount.

Thering is provided a kind of axicon lens ring type laser irradiating device, when laser beam irradiates thereon, it can produce annular Radiation source, it includes that coaxial the first plano-convex axicon lens being placed in parallel and the second plano-convex axicon lens, described first plano-convex are bored thoroughly Mirror is identical with the refractive index of described second plano-convex axicon lens, and the conical surface of described first plano-convex axicon lens and described second plano-convex cone are thoroughly The conical surface direction of mirror is identical, the base angle of described first plano-convex axicon lens less than the base angle of described second plano-convex axicon lens, described the The base angle of one plano-convex axicon lens and the second plano-convex axicon lens is respectively less than 5 °.

It is also preferred that the left when the distance between described first plano-convex axicon lens and described second plano-convex axicon lens is d₁Time, described 0 side-play amount exposure spots of the generation of axicon lens ring type laser irradiating device is apart from distance d of described second plano-convex axicon lens₂Meet Formula:

$d_2=\[d_1\·(n-1){\mathrm{\θ}}_1-r_0+\frac{b\·{\mathrm{cot\θ}}_2+a-d_1\·(n-1){\mathrm{\θ}}_1+r_0}{(1-\frac{1}{n}){\mathrm{\θ}}_1+\cos \left(1-\frac{1}{n}\right){\mathrm{\θ}}_1\·{\mathrm{cot\θ}}_2}\·\left(1-\frac{1}{n}\right){\mathrm{\θ}}_1\]\·\cos (n-1)({\mathrm{\θ}}_2-{\mathrm{\θ}}_1)$

Wherein, n is the first plano-convex axicon lens and the refractive index of the second plano-convex axicon lens, θ₁It it is the end of the first plano-convex axicon lens Angle, θ₂It is the base angle of the second plano-convex axicon lens, r₀For the laser beam radius after expanding, b is the end of the second plano-convex axicon lens Width, a is the radius of the second plano-convex axicon lens, 0 ° of ＜ θ₁＜ θ₂＜ 5 °.

It is also preferred that the left when distance d between described first plano-convex axicon lens and the second plano-convex axicon lens₁When immobilizing, change Become distance d of 0 side-play amount exposure spots and the second plano-convex axicon lens₂, i.e. can get continually varying annular radiation source, this annular The internal diameter r of radiation source₂Meet formula:

r₂=(d₂-d)·cot(n-1)(θ₂-θ₁)

Wherein, d is the distance between annular radiation source and the second plano-convex axicon lens.

The beneficial effects of the present invention is compared with the prior art: a kind of axicon lens ring type laser irradiation that the present invention provides Device solves needs by repeatedly moving into, remove axicon lens to realize the drawback of 0 side-play amount in prior art, it is to avoid due to The irradiation non-uniformity that resetting causes.

Accompanying drawing explanation

For the technical scheme being illustrated more clearly that in various embodiments of the present invention, required in embodiment being described below The accompanying drawing used is briefly described.

The structural representation of a kind of axicon lens ring type laser irradiating device that Fig. 1 provides for the present invention；

Fig. 2 is the light path principle after the laser beam after expanding is radiated at this axicon lens ring type laser irradiating device Figure；

Fig. 3 is the schematic diagram of a kind of spatial deviation Raman spectroscopic detection system.

Detailed description of the invention

Below in conjunction with accompanying drawing, to the present invention, above-mentioned and other technical characteristic and advantage are described in more detail.

As it is shown in figure 1, the structural representation of a kind of axicon lens ring type laser irradiating device that Fig. 1 provides for the present invention, should Axicon lens ring type laser irradiating device includes: coaxial the first plano-convex axicon lens 1 and the second plano-convex axicon lens 2 being placed in parallel, should First plano-convex axicon lens 1 is identical with the refractive index of the second plano-convex axicon lens 2, the conical surface of the first plano-convex axicon lens 1 and the second plano-convex The conical surface direction of axicon lens 2 is identical, and the base angle of the first plano-convex axicon lens 1 is less than the base angle of the second plano-convex axicon lens 2, the first plano-convex The base angle of axicon lens 1 and the second plano-convex axicon lens 2 is respectively less than 5 °.When the laser after expanding is along above-mentioned two plano-convex axicon lens Optical axis direction incide the plane of the first plano-convex axicon lens 1 after, this New type conical lens ring type laser irradiating device just can produce Raw annular radiation source.

Distance between the first plano-convex axicon lens 1 and the second plano-convex axicon lens 2 is d₁Time, this New type conical lens ring type swashs Distance d of 0 side-play amount exposure spots distance the second plano-convex axicon lens 2 that light-irradiating device produces₂Meet formula (1):

$d_2=\[d_1\·(n-1){\mathrm{\θ}}_1-r_0+\frac{b\·{\mathrm{cot\θ}}_2+a-d_1\·(n-1){\mathrm{\θ}}_1+r_0}{(1-\frac{1}{n}){\mathrm{\θ}}_1+\cos \left(1-\frac{1}{n}\right){\mathrm{\θ}}_1\·{\mathrm{cot\θ}}_2}\·\left(1-\frac{1}{n}\right){\mathrm{\θ}}_1\]\·\cos (n-1)({\mathrm{\θ}}_2-{\mathrm{\θ}}_1)---\left(1\right)$

Wherein, n is the first plano-convex axicon lens 1 and the refractive index of the second plano-convex axicon lens 2, θ₁It it is the first plano-convex axicon lens 1 Base angle, θ₂It is the base angle of the second plano-convex axicon lens 2, r₀For the laser beam radius after expanding, b is that the second plano-convex cone is saturating The bottom width of mirror 2, a is the radius of the second plano-convex axicon lens 2,0 ° of ＜ θ₁＜ θ₂＜ 5 °.

Distance d between the first plano-convex axicon lens 1 and the second plano-convex axicon lens 2₁When immobilizing, change 0 side-play amount Exposure spots and distance d of the second plano-convex axicon lens 2₂, i.e. can get continually varying annular radiation source, this annular radiation source Internal diameter r₂Meet formula (2):

r₂=(d₂-d)·cot(n-1)(θ₂-θ₁) (2)

Wherein, d is the distance between annular radiation source and the second plano-convex axicon lens 2.

The process that how to obtain above-mentioned formula is described below, as in figure 2 it is shown, irradiate for the laser beam after expanding Light path principle figure after this axicon lens ring type laser irradiating device,

If it is α that light beam incides the angle of incidence of the first plano-convex axicon lens 1, incident ray is β with refraction light angle, refraction Angle is γ, the law of refraction can obtain:

α=θ₁, γ=alpha+beta (3)

Sin γ=1, n sin α=1 sin (alpha+beta) (4)

Base angle θ due to the first plano-convex axicon lens 1₁Less than 5 °, (4) formula can be equivalent to:

N α=alpha+beta (5)

That is: β=(n-1) α=(n-1) θ₁ (6)

Dot spacing is submitted from AB=d with light beam at optical axis OO ' in the summit making the first plano-convex axicon lens 1 in Fig. 2₀, two cones are thoroughly Spacing AQ=d of mirror₁, the internal radius that light beam is formed on the second plano-convex axicon lens 2 is r₁, can obtain:

r₁=(d₁-d₀) tan β=(d₁-d₀) tan [(n-1) α]=d₁·tan[(n-1)θ₁]-r₀ (8)

If the angle of incidence of unirefringence is β in the second plano-convex axicon lens 2, refraction angle is β₁, the angle of incidence of birefringence is β₂, refraction angle is γ₂, the law of refraction can obtain:

1 sin β=n sin β₁ (9)

n·sinβ₂=1 sin γ₂ (10)

Base angle θ due to the second plano-convex axicon lens 2₂Less than 5 °, formula (9) and (10) can be equivalent to respectively:

β=n β₁, n β₂=γ₂ (11)

From geometrical relationship: β₁+β₂=θ₂ (12)

Be can get by formula (11) and (12):

γ₂=n β₂=n (θ₂-β₁)=n θ₂-β (13)

Work as γ₂=θ₂Time, refraction light is parallel with optical axis, now meets:

γ₂=n θ₂-β=θ₂ (14)

It follows that β=(n-1) θ₂ (15)

That is: θ₂=α=θ₁ (16)

Thus can obtain, when two axicon lens base angles meet 0 ° of ＜ θ₁＜ θ₂During the relation that ＜ is 5 °, emergent ray can intersect at optical axis On a bit, 0 side-play amount irradiation can be realized at this point.

If summit is D in the second plano-convex axicon lens 2, radius is a, and bottom width is b, and outgoing beam and optical axes crosspoint are E, with the Two plano-convex axicon lens 2 front surface intersection points are F, cross F and are vertical line GF, γ to optical axis₃For the angle of GF Yu EF, make DE=d₂, by geometry Relation can obtain:

${\mathrm{\γ}}_3={\mathrm{\θ}}_2+(\frac{\mathrm{\π}}{2}-{\mathrm{\γ}}_2)---\left(17\right)$

GF=r₁+CF·sinβ₁ (18)

GD=GF tan θ₂ (19)

d₂=DE=GE-GD=GF (tan γ₃-tanθ₂) (20)

The normal and the second plano-convex axicon lens 2 front surface that extend incident ray meet at M, geometrical relationship can obtain:

CM=b+a tan θ₂-r₁·tanθ₂ (21)

$CF=\frac{CM\·{\mathrm{cot\θ}}_2}{{\mathrm{sin\β}}_1+{\mathrm{cos\β}}_1\·{\mathrm{cot\θ}}_2}---\left(22\right)$

Arrangement can obtain:

$d_2=\[r_1+\frac{(b+a\·{\mathrm{tan\θ}}_2-r_1\·{\mathrm{tan\θ}}_2)\·{\mathrm{cot\θ}}_2}{{\mathrm{sin\β}}_1+{\mathrm{cos\β}}_1\·{\mathrm{cot\θ}}_2}\·{\mathrm{sin\β}}_1\]\·({\mathrm{tan\γ}}_3-{\mathrm{tan\θ}}_2)---\left(23\right)$

By γ₂=n θ₂-β,β=(n-1) θ₁, β=n β₁Substitute into:

${\mathrm{\γ}}_3=\frac{\mathrm{\π}}{2}-(n-1)({\mathrm{\θ}}_2-{\mathrm{\θ}}_1)---\left(24\right)$

$\begin{array}{c}{d}_2=\{d_1\·tan\[(n-1){\mathrm{\θ}}_1\]-r_0+\frac{b\·{\mathrm{cot\θ}}_2+a-d_1\·tan\[(n-1){\mathrm{\θ}}_1\]+r_0}{\sin (1-\frac{1}{n}){\mathrm{\θ}}_1+\cos (1-\frac{1}{n}){\mathrm{\θ}}_1\·{\mathrm{cot\θ}}_2}\·sin(1-\frac{1}{n}\left){\mathrm{\θ}}_1\right\}\\ \·\[\cot (n-1)({\mathrm{\θ}}_2-{\mathrm{\θ}}_1)-{\mathrm{tan\θ}}_2\]\end{array}---\left(25\right)$

By small angle approximation, can abbreviation be:

$d_2=\[d_1\·(n-1){\mathrm{\θ}}_1-r_0+\frac{b\·{\mathrm{cot\θ}}_2+a-d_1\·(n-1){\mathrm{\θ}}_1+r_0}{(1-\frac{1}{n}){\mathrm{\θ}}_1+\cos (1-\frac{1}{n}){\mathrm{\θ}}_1\·{\mathrm{cot\θ}}_2}\·\left(1-\frac{1}{n}\right){\mathrm{\θ}}_1\]\·\cot (n-1)({\mathrm{\θ}}_2-{\mathrm{\θ}}_1)$

The internal diameter r of annular radiation source₂And distance d between the second plano-convex axicon lens 2 meets:

r₂=(d₂-d)·cotγ₃=(d₂-d)·cot(n-1)(θ₂-θ₁)

As it is shown on figure 3, be the schematic diagram of a kind of spatial deviation Raman spectroscopic detection system, this detection system is mainly for danger Danger product particularly liquid explosive measure, as the explosive acid sodium such as TNT, ammonium chloride, black powder, dimethylbenzene, hydrogen peroxide and Ethanol etc. generally contain the prohibited items of the groups such as nitro, amino, phenyl ring and detect.This detection device includes: laser instrument 101, expand device 102, axicon lens ring type laser irradiating device 103, signal collection device 104, band pass filter means 105, gather Coke installation 106, spectrogrph 107, computer 108 and one-dimensional movement platform 1010.Axicon lens ring type laser irradiating device 103 wraps Include: coaxial the first plano-convex axicon lens being placed in parallel and the second plano-convex axicon lens.This first plano-convex axicon lens and the second plano-convex cone The refractive index of lens is identical, and the conical surface of the first plano-convex axicon lens and the conical surface direction of the second plano-convex axicon lens are identical, the first plano-convex The base angle of axicon lens is less than the base angle of the second plano-convex axicon lens, and the base angle of the first plano-convex axicon lens and the second plano-convex axicon lens is the least In 5 °.

The laser that laser instrument 101 sends is injected and is expanded device 102, is formed and swash after expanding device 102 and carrying out beam-expanding collimation Light light beam, laser beam incides the plane of the first plano-convex axicon lens along the optical axis direction of two plano-convex axicon lens, through cone Annular radiation source is formed, by treating in this annular radiation source directive sample cell 109 after lens ring type laser irradiating device 103 Test sample product, change the distance between axicon lens ring type laser irradiating device 103 and testing sample by one-dimensional movement platform 1010, Realize the continuous variable regulation of annular radiation source internal diameter.By signal collection device 104 in the center of annular radiation source Carry out the collection of flashlight, then after all kinds of spurious signals that band pass filter means 105 eliminates beyond flashlight, by focusing on Device 106 focuses on the probe of spectrogrph 107, carries out spectrum analysis by computer.When annular radiation source internal diameter changes Time, the relative distance between shot point and bleeding point changes, and i.e. achieves the detection of spatial deviation Raman spectrum.

The axicon lens ring type laser irradiating device of the application and there is the spatial deviation Raman spectroscopic detection system of this device, Solve and prior art needs by repeatedly moving into, remove axicon lens to realize the drawback of 0 side-play amount, it is to avoid owing to repeating The irradiation non-uniformity that location causes.Only by one-dimensional square translation upwards, can realize spatial offset from 0 start continuous Adjustable, not only reduce the complexity of irradiation devices, improve its stability, economically feasible simultaneously.

The foregoing is only presently preferred embodiments of the present invention, be merely illustrative for the purpose of the present invention, and non-limiting 's.Those skilled in the art understands, it can be carried out many changes in the spirit and scope that the claims in the present invention are limited, Amendment, even equivalence, but fall within protection scope of the present invention.

Claims (3)

1. an axicon lens ring type laser irradiating device, when laser beam irradiates thereon, it can produce annular exposure light Source, it is characterised in that it includes coaxial the first plano-convex axicon lens being placed in parallel and the second plano-convex axicon lens, described first plano-convex Axicon lens is identical with the refractive index of described second plano-convex axicon lens, the conical surface of described first plano-convex axicon lens and described second plano-convex The conical surface direction of axicon lens is identical, and the base angle of described first plano-convex axicon lens is less than the base angle of described second plano-convex axicon lens, institute The base angle stating the first plano-convex axicon lens and the second plano-convex axicon lens is respectively less than 5 °.

A kind of axicon lens ring type laser irradiating device the most according to claim 1, it is characterised in that when described first plano-convex Distance between axicon lens and described second plano-convex axicon lens is d₁Time, the generation of described axicon lens ring type laser irradiating device 0 side-play amount exposure spots is apart from distance d of described second plano-convex axicon lens₂Meet formula:

$d_2=\[d_1\·\left(n-1\right){\mathrm{\θ}}_1-r_0+\frac{b\·{\mathrm{cot\θ}}_2+a-d_1\·\left(n-1\right){\mathrm{\θ}}_1+r_0}{\left(1-\frac{1}{n}\right){\mathrm{\θ}}_1+\cos \left(1-\frac{1}{n}\right){\mathrm{\θ}}_1\·{\mathrm{cot\θ}}_2}\·\left(1-\frac{1}{n}\right){\mathrm{\θ}}_1\]\·\cot \left(n-1\right)\left({\mathrm{\θ}}_2-{\mathrm{\θ}}_1\right)$

Wherein, n is the first plano-convex axicon lens and the refractive index of the second plano-convex axicon lens, θ₁It is the base angle of the first plano-convex axicon lens, θ₂ It is the base angle of the second plano-convex axicon lens, r₀For the laser beam radius after expanding, b is the bottom width of the second plano-convex axicon lens, a It is the radius of the second plano-convex axicon lens, 0 ° of ＜ θ₁＜ θ₂＜ 5 °.

A kind of axicon lens ring type laser irradiating device the most according to claim 2, it is characterised in that when described first plano-convex Distance d between axicon lens and the second plano-convex axicon lens₁When immobilizing, change 0 side-play amount exposure spots with the second plano-convex cone thoroughly Distance d of mirror₂, i.e. can get continually varying annular radiation source, the internal diameter r of this annular radiation source₂Meet formula:

r₂=(d₂-d)·cot(n-1)(θ₂-θ₁)

Wherein, d is the distance between annular radiation source and the second plano-convex axicon lens.