CN204807812U - Can produce optical system of single hollow light beam of local and hollow light beam of periodic local - Google Patents

Abstract

The utility model discloses a kind of optical system that can produce single bottle beams and periodical bottle beams,It include the laser set gradually along optical path,Telescope beam-expanding collimation device,Cylindrical lens and axicon,The radius of cylindrical lens is b, and the bottom surface radius of axicon is c,c amp; gt; B,The bottom surface of cylindrical lens is offered using this bottom surface as circular cone bottom surface and the indent conical cavity coaxial and contour with cylindrical lens,The bottom surface radius of this indent conical cavity is a,a amp; lt; B,The base angle r1 of this indent conical cavity is less than the base angle r2 of axicon,The bottom surface of this indent conical cavity towards the bottom surface of axicon,The distance between cylindrical lens and axicon are L, lt; maths num="0001" gt; ***NO_TRANS_Pr0000*** lt; /maths gt; Huo amp; lt; maths num="0002" gt; lt; /maths gt; The utility model can easily obtain single bottle beams and periodical bottle beams using a set of optical system, and structure is simple, and number of elements is few in system, and element processing is relatively easy, does not have particular/special requirement to Refractive Index of Material.

Description

Optical system for generating single and periodic localized hollow-core beams

technical field

The utility model relates to an optical system capable of generating a single localized hollow beam and a periodic localized hollow beam.

Background technique

Local hollow beam (Bottle beam) refers to a special hollow beam with zero intensity in the propagation direction of the beam, and the three-dimensional space outside this area is surrounded by high-intensity beams. Because it has a three-dimensional closed dark hollow area and a very high intensity gradient, it can be used in the fields of particle capture and optical manipulation of particles, so the generation and application of hollow local beams have become a very important topic in the field of optics.

Local hollow beams are divided into two types: single local hollow beams and periodic local hollow beams according to the generation situation. The two localized hollow beams have their own characteristics: a single localized hollow beam can generate a larger-sized dark hollow area, which can be used for manipulation of larger-sized particles; the dark hollow area of a periodic localized hollow beam is smaller, but once Multiple dark hollow areas can be generated to achieve multi-level manipulation of particles. Therefore, the application occasions of the two local hollow beams are also different.

Existing optical systems that can generate a single localized hollow beam cannot generate periodic localized hollow beams, but can generate periodic localized hollow beams but cannot generate a single localized hollow beam, which is extremely unfavorable for the practical application of localized hollow beams.

In view of this, the inventors conducted in-depth research on the problems existing in the existing optical system for generating localized hollow beams, and this case arose from it.

Utility model content

The purpose of the utility model is to provide an optical system capable of generating a single localized hollow beam and a periodic localized hollow beam.

In order to achieve the above object, the utility model adopts the following technical solutions:

An optical system capable of generating a single localized hollow beam and a periodic localized hollow beam, including a laser, a telescope beam expander collimator, a cylindrical lens and an axicon arranged in sequence along the optical path, the radius of the cylindrical lens is b, The radius of the bottom surface of the axicon is c, c>b, and the bottom surface of the cylindrical lens is provided with a concave conical cavity with the bottom surface as the bottom surface of the cone and coaxial with the cylindrical lens and equal in height. The radius of the bottom surface of the concave conical cavity is a, a<b, the bottom angle r ₁ of the concave conical cavity is smaller than the bottom angle r ₂ of the axicon, the bottom surface of the concave conical cavity faces the bottom surface of the axicon, and the distance between the cylindrical lens and the axicon is L , $0<L<\frac{b(r_2-r_1)}{r_2{\mathrm{tanr}}_1}$ or $\frac{b(r_2-r_1)}{r_2{\mathrm{tanr}}_1}<L<\frac{c}{{\mathrm{tanr}}_1}.$

After adopting the above scheme, the utility model is an optical system that can generate a single local hollow beam and a periodic local hollow beam. The laser beam generated by the laser is expanded and collimated by the telescope beam expander and collimator to form an approximate plane wave, and the plane wave passes through the The cylindrical lens with concave conical cavity is divided into two parts (the middle part and the peripheral ring part). The light beam is transmitted forward to the bottom of the axicon. The peripheral ring part maintains the original optical properties of the normal incidence of the bottom of the axicon. The middle part is concave Under the action of the conical cavity, it is transformed into a conical surface wave incident at the bottom of the axicon with a divergence angle r ₁ , and the distance L between the cylindrical lens and the axicon is adjusted, when A single local hollow beam can be obtained when , a periodic localized hollow beam can be generated. The utility model adopts a set of optical system to conveniently obtain a single localized hollow beam and a periodic localized hollow beam, and has a simple structure, a small number of components in the system, relatively easy component processing, and no special requirements on the refractive index of the material. It provides a simple and effective new way to obtain local hollow beams.

Description of drawings

Fig. 1 is the structural representation of the utility model optical system;

Fig. 2 a is the side view of cylindrical lens among Fig. 1; Fig. 2 b is the perspective view of cylindrical lens among Fig. 1;

Fig. 3 a is the side view of axicon in Fig. 1; Fig. 3 b is the perspective view of axicon in Fig. 1;

Fig. 4 is the schematic diagram of the principle that the optical system of the present invention generates a single local hollow beam;

Fig. 5 is a schematic diagram of the principle of generating periodic localized hollow beams by the optical system of the present invention.

Detailed ways

The utility model is an optical system capable of producing a single localized hollow beam and a periodic localized hollow beam, as shown in Figure 1, comprising a laser 100, a telescope beam expander and collimator 200, which are sequentially arranged along the optical path on the optical rail, Cylindrical lens 300 and axicon 400 .

As shown in Figures 2a, 2b, 3a, and 3b, the radius of the cylindrical lens 300 is b, the radius of the bottom surface of the axicon is c, c>b, and a bottom surface 31 of the cylindrical lens 300 is provided with the bottom surface 31 as a conical bottom surface and A concave conical cavity 32 coaxial with the cylindrical lens 300 and equal in height, the radius of the bottom surface of the concave conical cavity 32 is a, where a<b. During processing, a concave conical cavity 32 coaxial with the cylindrical lens 300 and of the same height can be ground at the center position of the bottom surface 31 of the cylindrical lens 300, and the bottom surface 31 of the cylindrical lens 300 is divided by the concave conical cavity 32. Two parts, namely, the middle part with radius a corresponding to the bottom surface of the concave conical cavity 32 and the remaining peripheral annular part. And the base angle r ₁ of the concave conical cavity 300 is smaller than the base angle r ₂ of the axicon 400 . In the optical system of the present invention, the bottom surface of the concave conical cavity 32 faces the bottom surface of the axicon 400 .

The principle of the utility model to generate a single local hollow beam and a periodic local hollow beam is as follows:

The laser beam that laser 100 produces is through telescopic beam expander collimator 200 beam expansion collimation and forms approximate plane wave, and plane wave is divided into two parts light beams (shown by solid line in Fig. and dotted lines represent respectively) forward to the bottom of the axicon 400: (1) the light beam injected into the peripheral annular part maintains the original optical properties of the positive incident axicon 400 bottom, represented by the dotted line in Figures 4 and 5; (2) injected into the axicon 400 bottom Under the action of the concave conical cavity 32, the light beam in the middle part is transformed into a cone surface wave incident on the bottom of the axicon 400 with a divergence angle r ₁ , which is represented by a solid line in FIGS. 4 and 5 .

The light beam (dotted line) that enters the peripheral annular part is transformed into a cone surface wave with a converging angle r ₂ under the action of the axicon 400, forming a Bessel beam area ABCD on the optical axis; a cone surface wave with a divergence angle r ₁ ( The solid line) is transformed into a new cone wave with a converging angle r ₂ -r ₁ under the action of the axicon 400, forming a Bessel beam region EFGH on the optical axis.

In FIGS. 4 and 5 , L is the distance between the cylindrical lens 300 with a concave conical cavity and the axicon 400 .

(1) As shown in Figure 4, when , there will be a dark hollow area enclosed by peripheral beams in the middle of the two Bessel beam areas ABCD and EFGH (indicated by black shadow in Figure 4), that is, a single local hollow beam. And increasing L can increase the size of this dark hollow region; decreasing L can reduce the size of this dark hollow region.

(2) As shown in Figure 5, when , the two Bessel beam areas ABCD and EFGH will intersect, that is, the two areas have a common part (indicated by black shading in Figure 5). Since the converging angles of the cone waves forming the two Bessel beams are different (r ₂ and r ₂ −r ₁ , respectively), the longitudinal wave vectors of the two Bessel beams are also different. Two Bessel beams with different longitudinal wave vectors are coherently superimposed in the common part of the two Bessel beam regions ABCD and EFGH (the black shaded part in Fig. 5) to form a periodic localized hollow beam.

The optical system of the utility model can conveniently obtain a single localized hollow beam and a periodic localized hollow beam by adopting a set of optical system, and the structure is simple, the number of components in the system is small, the processing of the components is relatively easy, and there is no special effect on the refractive index of the material. Require. It provides a simple and effective new way to obtain local hollow beams.

Claims (1)

1. one kind can produce the optical system of single bottle beams and periodicity bottle beams, it is characterized in that: comprise the laser instrument, telescope beam-expanding collimation device, cylinder lenses and the axle pyramid that set gradually along light path, the radius of cylinder lenses is b, the bottom surface radius of axle pyramid is c, c>b, the bottom surface of cylinder lenses offers with this bottom surface for circular cone bottom surface and the indent conical cavity coaxial and contour with cylinder lenses, the bottom surface radius of this indent conical cavity is a, a<b, the base angle r of this indent conical cavity ₁be less than the base angle r of axle pyramid ₂, the bottom surface of this indent conical cavity is towards the bottom surface of axle pyramid, and the distance between cylinder lenses and axle pyramid is L, $0<L<\frac{b(r_2-r_1)}{r_2{\mathrm{tanr}}_1}$ Or $\frac{b(r_2-r_1)}{r_2{\mathrm{tanr}}_1}<L<\frac{c}{{\mathrm{tanr}}_1}.$