CN101363956A - Device for forming quasi-double half-gauss hollow laser beam - Google Patents

Abstract

The invention discloses a quasi-double semi-gaussian hollow laser beam forming apparatus which realizes the conversion from a gaussian solid laser beam to a quasi-double semi-gaussian hollow laser beam to a certain extent, and belongs to the laser technical field. The prior hollow laser beam forming apparatus adopting the geometrical optics method has the defects that the light intensity of the formed hollow laser beam still has double-gaussian distribution, and the formed laser beam is not a practical hollow laser beam. The quasi-double semi-gaussian hollow laser beam forming apparatus is sequentially composed of a concave spherical reflecting mirror, a normal conical surface reflecting mirror and a positive lens, the three of which are coaxial in optics; the conical surface of the normal conical surface reflecting mirror is opposite to the concave spherical surface of the concave spherical reflecting mirror; an incident hole is formed in the center of the concave spherical reflecting mirror; and the object focal point of the positive lens is coincident to the reflected light convergence dot of the concave spherical reflecting mirror. The light intensity distribution of the hollow laser beam formed by the apparatus is near the quasi-double semi-gaussian distribution state, and the formed laser beam is the quasi-double semi-gaussian hollow laser beam applied to the fields of laser processing, atom cooling, bioengineering and the like.

Description

Quasi-double half-gauss hollow laser beam forms device

Technical field

The present invention relates to a kind of quasi-double half-gauss hollow laser beam and form device, realized of the conversion of the solid laser beam of Gauss to a certain extent, belong to laser technology field to double half-gauss hollow laser beam.

Background technology

The characteristics of desirable hollow laser beam are that the inwall light distribution is steep, and hollow area is unglazed fully, see shown in Figure 1ly, are referred to as double half-gauss hollow laser beam.The hollow laser beam just practical near desirable hollow laser beam can be applicable to fields such as Laser Processing, atom cooling, bioengineering.Up to the present, formation with regard to hollow laser beam has proposed multiple scheme, as transverse mode back-and-forth method, geometrical optics approach, Identification with Method of Optical Holography, calculation holographic method, mode switch method, rotating prism method etc., these schemes can realize the conversion of the solid laser beam of Gauss shown in Figure 2 to double gauss hollow laser beam shown in Figure 3, as seen, the hollow laser beam inwall light distribution that is obtained not is steep, and hollow area is not unglazed fully.In order to obtain desirable hollow laser beam, application number is that the Chinese invention patent application of 200410016728.X discloses the technical scheme that a name that belongs to geometrical optics approach is called single pyramid collimation hollow laser beam generation device, see shown in Figure 4, the structure of this device is, the place ahead in single pyramid 1 and 2 combinations of rearmounted catoptron, the middle mirror in front 4 that aperture 3 is arranged of one side is set, aperture 3 is positioned on the light path light axis, incident laser is from these aperture 3 incidents, through single pyramid 1 and rearmounted catoptron 2, reflect again to enter after single pyramid 1 deflection and reflected to form collimation hollow laser beam 5, but, still be the double gauss distribution through its light intensity of experiment test by mirror in front 4.This technique effect and Yong Qian (money is brave) and Yuzhu Wang (Wang Yuzhu) are at CHINESE OPTICS LETTERS/Vol.2, No.4/April10, the double gauss of analyzing in 2004 papers of delivering that are entitled as Theoretical analysis of a collimated hollow-laser-beam generatedby a single axicon using diffractive integral distributes and conforms to, and its effect only has been to improve the unglazed degree of hollow laser beam hollow area.

Summary of the invention

Its deficiency of described known technology is, formed hollow laser beam light intensity still distributes for double gauss, do not become a kind of hollow laser beam of practicality as yet, therefore, steep in order to obtain the inwall light distribution, the practical hollow laser beam of the further reduction of the unglazed degree of hollow area simultaneously, the quasi-double half-gauss hollow laser beam that we have invented the present invention forms device.

The present invention realizes like this, see Fig. 5, shown in Figure 6, quasi-double half-gauss hollow laser beam forms device and is made up of concave spherical mirror 6, positive axis conical reflector 7, positive lens 8 successively, three's optics is coaxial, the conical surface of positive axis conical reflector 7 is relative with the concave spherical surface of concave spherical mirror 6, and the center of concave spherical mirror 6 has into perforation 9; Concave spherical mirror 6 should meet following formula requirement with positive axis conical reflector 7 parameter matching relation and position relation:

$x=\frac{-y_A}{\mathrm{tg}(\mathrm{\θ}+\mathrm{\α}/2)}+x_A$

In the formula: $\mathrm{\α}=\arcsin \left[\frac{(R/2-l)\sin \mathrm{\θ}}{R}\right]$

The concave sphere's center O of concave spherical mirror 6 is a true origin, and optical axis overlaps with horizontal ordinate, and R is the concave spherical surface radius, and θ is the cone angle of positive axis conical reflector 7 conical surfaces, and 1 is the distance of the vertex of a cone of positive axis conical reflector 7 conical surfaces to concave spherical mirror 6 focus O ', A (x _A, y _A) for the solid gauss laser of incident intrafascicular any one by the light of positive axis conical reflector 7 reflection and the intersection point of concave spherical mirror 6, α is for intersecting at an A (x _A, y _A) positive axis conical reflector 7 reflection rays with cross a some A (x _A, y _A) angle between the concave spherical surface radius R, concave spherical mirror 6 reflection rays and optical axis intersection are in an O ＂, and x is a some O ＂ abscissa value; The focus in object space of positive lens 8 overlaps with some O ＂, and f is the object space focal length of positive lens 8.

The technique effect of the present invention's device is that the central ray A light intensity I of the solid Gaussian laser beam of incident is the strongest, and is the most weak at a distance of the light intensity I of the marginal ray B of spot radius r with central ray A.The solid Gaussian laser beam of incident is from going into perforation 9 incidents, shine on the reflection conical surface of positive axis conical reflector 7, be converted into the hollow cone laser beam of dispersing after the reflection, reflect through concave spherical mirror again, be converted to the hollow cone laser beam that converges, and central ray A, marginal ray B and between the transition light between the two all by 1 O ＂ on the optical axis, be converted to the hollow cylinder laser beam of collimation again through positive lens 8, its hot spot is seen shown in Figure 7 ringwise.Ring-shaped light spot inwall light A is the solid Gaussian laser beam central ray of incident A, light intensity I is the strongest, ring-shaped light spot outer wall light B is the solid Gaussian laser beam marginal ray of incident B, light intensity I is the most weak, the light distribution experiment test the results are shown in shown in Figure 8, being near the double half-gauss distribution, is a kind of quasi-double half-gauss hollow laser beam, has realized goal of the invention.

Description of drawings

Fig. 1 is a double half-gauss hollow laser beam light distribution synoptic diagram.Fig. 2 is the solid laser beam intensity distribution schematic diagram of Gauss.Fig. 3 is a double gauss hollow laser beam light distribution synoptic diagram.Fig. 4 is known single pyramid collimation hollow laser beam generation device structure and collimation hollow laser beam production process synoptic diagram.Fig. 5 is that the application's quasi-double half-gauss hollow laser beam forms apparatus structure and quasi-double half-gauss hollow laser beam forming process synoptic diagram, and this figure double as is a Figure of abstract.Fig. 6 is that the application's quasi-double half-gauss hollow laser beam forms in the device that concave spherical mirror concerns with positive axis conical reflector parameter matching and the position concerns synoptic diagram.Fig. 7 is the application's quasi-double half-gauss hollow laser beam ring-shaped light spot synoptic diagram.Fig. 8 is the application's quasi-double half-gauss hollow laser beam light distribution experiment test curve map.

Embodiment

See Fig. 5, shown in Figure 6, double half-gauss hollow laser beam forms device to be made up of concave spherical mirror 6, positive axis conical reflector 7, positive lens 8 successively, and three's optics is coaxial, and the conical surface of positive axis conical reflector 7 is relative with the concave spherical surface of concave spherical mirror 6.Concave spherical mirror 6, positive axis conical reflector 7 adopt metal or glass material to make, and concave spherical surface, the conical surface are optical polish, and are coated with metal or dielectric reflection film.Concave spherical mirror 6, positive axis conical reflector 7 belong to optical mirror.The center of concave spherical mirror 6 has into perforation 9, and its aperture is more than or equal to the solid gauss laser beam diameter of incident.The bottom surface of positive axis conical reflector 7 and level crossing 10 1 side mirror faces are bonding, level crossing 10 adopts anti-damage threshold height, the high glass material of operation wavelength laser transmittance is made, work to support positive axis conical reflector 7, see through light simultaneously by concave spherical mirror 6 reflections.Concave spherical mirror 6 should meet following formula requirement with positive axis conical reflector 7 parameter matching relation and position relation:

$x=\frac{-y_A}{\mathrm{tg}(\mathrm{\θ}+\mathrm{\α}/2)}+x_A$

In the formula: $\mathrm{\α}=\arcsin \left[\frac{(R/2-l)\sin \mathrm{\θ}}{R}\right]$

The concave sphere's center O of concave spherical mirror 6 is a true origin, and optical axis overlaps with horizontal ordinate, and R is the concave spherical surface radius, and θ is the cone angle of positive axis conical reflector 7 conical surfaces, and 1 is the distance of the vertex of a cone of positive axis conical reflector 7 conical surfaces to concave spherical mirror 6 focus O ', A (x _A, y _A) for the solid gauss laser of incident intrafascicular any one by the light of positive axis conical reflector 7 reflection and the intersection point of concave spherical mirror 6, α is for intersecting at an A (x _A, y _A) positive axis conical reflector 7 reflection rays with cross a some A (x _A, y _A) angle between the concave spherical surface radius R, concave spherical mirror 6 reflection rays and optical axis intersection are in an O ＂, and x is a some O ＂ abscissa value; The focus in object space of positive lens 8 overlaps with some O ＂, and f is the object space focal length of positive lens 8.

Corresponding 13 the concrete schemes of 13 groups of supplemental characteristics that last table provides.For example the 9th group of pairing scheme of parameter is, the solid gauss laser beam diameter of incident is 2mm, the concave spherical surface radius R is 20mm, conical surface taper angle theta is 120 °, conical surface bottom surface diameter of phi is 6mm, the vertex of a cone of positive axis conical reflector 7 conical surfaces is 4.5mm to concave spherical mirror 6 focus O's ' apart from l, and the thickness d of level crossing 10 is 1.5mm, clear aperature D ₁Be 20mm, the object space focal distance f of positive lens 8 is 40mm, the radius of curvature R of two spheres ₁, R ₂Equate, be 43.2mm, clear aperature D ₂Be 18m.

Claims (5)

1, a kind of quasi-double half-gauss hollow laser beam forms device, it is characterized in that, this device is made up of concave spherical mirror (6), positive axis conical reflector (7), positive lens (8) successively, three's optics is coaxial, the conical surface of positive axis conical reflector (7) is relative with the concave spherical surface of concave spherical mirror (6), and the center of concave spherical mirror (6) has into perforation (9); Concave spherical mirror (6) should meet following formula requirement with positive axis conical reflector (7) parameter matching relation and position relation:

$x=\frac{-y_A}{\mathrm{tg}(\mathrm{\θ}+\mathrm{\α}/2)}+x_A$

In the formula: $\mathrm{\α}=\arcsin \left[\frac{(R/2-l)\sin \mathrm{\θ}}{R}\right]$

The concave sphere's center O of concave spherical mirror (6) is a true origin, optical axis overlaps with horizontal ordinate, and R is the concave spherical surface radius, and θ is the cone angle of positive axis conical reflector (7) conical surface, 1 is the distance of the vertex of a cone of positive axis conical reflector (7) conical surface to concave spherical mirror (6) focus O ', A (x _A, y _A) for the solid gauss laser of incident intrafascicular any one by the light of positive axis conical reflector (7) reflection and the intersection point of concave spherical mirror (6), α is for intersecting at an A (x _A, y _A) positive axis conical reflector 7 reflection rays with cross a some A (x _A, y _A) angle between the concave spherical surface radius R, concave spherical mirror (6) reflection ray and optical axis intersection are in an O ＂, and x is a some O ＂ abscissa value; The focus in object space of positive lens (8) overlaps with some O ＂, and f is the object space focal length of positive lens (8).

2, form device according to the described hollow laser beam of claim 1, it is characterized in that, concave spherical mirror (6), positive axis conical reflector (7) adopt metal or glass material to make, and concave spherical surface, the conical surface are optical polish, and are coated with metal or dielectric reflection film.Concave spherical mirror (6), positive axis conical reflector (7) belong to optical mirror.

3, form device according to the described hollow laser beam of claim 1, it is characterized in that, go into perforation (9) aperture more than or equal to the solid gauss laser beam diameter of incident.

4, form device according to the described hollow laser beam of claim 1, it is characterized in that, be bonded with level crossing (10) in the bottom surface of positive axis conical reflector (7), level crossing (10) adopts anti-damage threshold height, the high glass material of operation wavelength laser transmittance is made.

5, form device according to the described hollow laser beam of claim 1, it is characterized in that the radius of curvature R of two spheres of positive lens (8) ₁, R ₂Equate.

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