A scintillator beam collimation system

Abstract

The application discloses a scintillator light beam collimation system, and relates to the field of light beam shaping. The system comprises an ellipsoidal reflector, a free-form surface collimation reflector cup and a free-form surface collimation lens. The scintillator is arranged at a first focal point of the ellipsoidal reflector. The ellipsoidal reflector is used for converging light rays emitted by the side of the scintillator at a second focal point of the ellipsoidal reflector. The free-form surface collimation reflector cup is connected with the ellipsoidal reflector. The free-form surface collimation reflector cup is used for collimating light emitted by the scintillator and exceeding a demarcation angle and light converging by the ellipsoidal reflector. The free-form surface collimation lens is used for collimating light emitted by the scintillator and smaller than the demarcation angle and light converging by the ellipsoidal reflector. The application can improve the light beam collimation effect of the scintillator.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of light beam shaping, in particular to a scintillator light beam collimation system. BACKGROUND

[0002] The scintillator is a functional material capable of converting incident X-rays, gamma rays or other high-energy particles into visible light or ultraviolet light, and plays a very important role in the field of radiation detection. In medicine, the scintillator is the core component of nuclear medical imaging equipment, which can quickly diagnose the lesions of various organs of the human body and treat them. The scintillator can also capture the information of various particles generated after nuclear reaction, which is used for the detection of high-energy particles. It also plays an irreplaceable role in the fields of security check, non-destructive testing, radioactive detection, environmental monitoring, etc. Since the light emission angle of the scintillator after excitation is large and the light emission area is large, and the side surface also emits light, it is difficult to achieve efficient collection and utilization of the light energy of the radiation. Therefore, the current detection of the scintillator mostly collects light in a small range by using the aperture of the detection system. At the same time, due to the low light energy utilization rate, a large dose of radiation is required to achieve high imaging quality and treatment effect, which causes great damage to the human body, further limiting the application of the scintillator in medical treatment. Therefore, collimating the light emitted by the scintillator is an important link in the design of the scintillator light beam shaping.

[0003] High-energy particles irradiated onto the scintillator make it emit light, and the light emission surface of the scintillator can be regarded as a large-size area light source. For a large-size area light source, if it is regarded as a point light source, it is difficult to achieve good collimation effect by using a spherical or aspherical lens with low degrees of freedom. SUMMARY

[0004] The purpose of the present application is to provide a scintillator light beam collimation system, which can improve the light beam collimation effect of the scintillator.

[0005] To achieve the above-mentioned purpose, the present application provides the following solutions:

[0006] A scintillator light beam collimation system, comprising: an ellipsoidal reflector, a free-form surface collimation reflector cup and a free-form surface collimation lens;

[0007] The scintillator is arranged at a first focal point of the ellipsoidal reflector; the ellipsoidal reflector is used for converging the light emitted by the side surface of the scintillator at a second focal point of the ellipsoidal reflector; the free-form surface collimation reflector cup is connected with the ellipsoidal reflector; the free-form surface collimation reflector cup is used for collimating the light emitted by the scintillator beyond a demarcation angle and the light converged by the ellipsoidal reflector; and the free-form surface collimation lens is used for collimating the light emitted by the scintillator less than the demarcation angle and the light converged by the ellipsoidal reflector.

[0008] Optionally, the ellipsoidal reflector, the scintillator, the free-form collimating reflector cup and the free-form collimating lens are located on the same optical axis.

[0009] Optionally, a small hole is arranged on the side of the ellipsoidal reflector away from the scintillator; the small hole is used for the incidence of excitation light.

[0010] Optionally, the demarcation angle is the angle between the light and the optical axis; the demarcation angle is 30 degrees.

[0011] Optionally, the side of the free-form collimating lens close to the scintillator is a spherical surface; the spherical center of the spherical surface is the second focal point of the ellipsoidal reflector.

[0012] Optionally, the scintillator is a cuboid light source.

[0013] Optionally, the free-form collimating lens is obtained by cutting a hollow cube around the rotation body of the collimating lens free-form generatrix; the face diagonal size of the hollow cube is the distance between the endpoints of the collimating lens free-form generatrix; the collimating lens free-form generatrix is obtained by weighted superposition of the intersection points of the first straight line and the transmission free-form generatrix; the first straight line is determined according to the demarcation angle; the transmission free-form generatrix is determined by the scintillator and the refraction law.

[0014] Optionally, the free-form collimating lens is obtained by cutting a hollow cube around the merged body; the edge length size of the hollow cube is the distance between the endpoints of the collimating lens free-form generatrix; the merged body is obtained by merging a plurality of free-form collimating column lens entities; the free-form collimating column lens entity is obtained by translating the transmission free-form generatrix in a direction perpendicular to the design unit angle; the transmission free-form generatrix is determined by the scintillator and the refraction law; the design unit is a row of point light sources arranged at an angle along the scintillator.

[0015] Optionally, the free-form collimating reflector cup is obtained by rotating the collimating light-emitting cup free-form generatrix around the optical axis; the collimating light-emitting cup free-form generatrix is obtained by weighted superposition of the intersection points of the second straight line and the reflection free-form surface; the second straight line is determined according to the demarcation angle; the reflection free-form surface is determined by the scintillator and the reflection law.

[0016] According to the specific embodiments of the present application, the following technical effects are provided:

[0017] The scintillator is arranged at a first focal point of the ellipsoidal reflector; the ellipsoidal reflector is used for converging light emitted by the scintillator at a side of the scintillator to a second focal point of the ellipsoidal reflector; the free-form surface collimating reflector cup is connected with the ellipsoidal reflector; the free-form surface collimating reflector cup is used for collimating light emitted by the scintillator and converging by the ellipsoidal reflector and exceeding a demarcation angle; and the free-form surface collimating lens is used for collimating light emitted by the scintillator and converging by the ellipsoidal reflector and less than the demarcation angle. The light emitted by the scintillator in each direction is collimated through the ellipsoidal reflector, the free-form surface collimating reflector cup and the free-form surface collimating lens, so that the light beam collimation effect of the scintillator is improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0019] Figure 1 A schematic diagram of the scintillator light beam collimation system provided by the present application is shown in the figure.

[0020] Fig. 2(a)-Fig. 2(c) are schematic diagrams of the ellipsoidal reflector.

[0021] Fig. 3(a)-Fig. 3(e) are schematic diagrams of the design process of the free-form surface collimating lens and the obtained lens entity.

[0022] Fig. 4(a)-Fig. 4(d) are schematic diagrams of the design process of the free-form surface collimating reflector cup and the obtained reflector cup entity.

[0023] Figure 5 Fig. 5 is a simulation diagram of the light beam collimation system for shaping the light emitted by the scintillator.

[0024] Fig. 6(a)-Fig. 6(c) are far-field light intensity profile comparison diagrams of the light emitted by the scintillator before and after shaping by the system provided by the embodiments of the present application.

[0025] Symbol explanation:

[0026] 1-ellipsoidal reflector, 2-scintillator, 3-free-form surface collimating reflector cup, 4-free-form surface collimating lens. DETAILED DESCRIPTION

[0027] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0028] The present application aims to provide a scintillator light beam collimation system, which can improve the light beam collimation effect of the scintillator.

[0029] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0030] As shown in Figure 1 and Figure 5 The present application provides a scintillator light beam collimation system, which comprises an ellipsoidal reflector 1, a free-form surface collimation reflector cup 3 and a free-form surface collimation lens 4.

[0031] The scintillator 2 is arranged at the first focal point of the ellipsoidal reflector 1; the ellipsoidal reflector 1 is used for converging the light emitted by the side surface of the scintillator 2 at the second focal point of the ellipsoidal reflector 1; the free-form surface collimation reflector cup 3 is connected with the ellipsoidal reflector 1; the free-form surface collimation reflector cup 3 is used for collimating the light emitted by the scintillator 2 beyond the demarcation angle and the light converged by the ellipsoidal reflector 1; and the free-form surface collimation lens 4 is used for collimating the light emitted by the scintillator 2 less than the demarcation angle and the light converged by the ellipsoidal reflector 1. The second focal point is set on the optical axis, in front of the light emitting surface of the scintillator 2 and close to the scintillator 2, at this time, the converged light at the focal point can be regarded as a point light source, which is collimated through the free-form surface collimation lens 4 and the free-form surface collimation reflector cup 3 designed subsequently. A small hole is opened on the ellipsoidal reflector 1 for the incidence of excitation light.

[0032] The ellipsoidal reflector 1, the scintillator 2, the free-form collimating reflector cup 3 and the free-form collimating lens 4 are located on the same optical axis. A small hole is arranged on the side of the ellipsoidal reflector 1 away from the scintillator 2; the small hole is used for the incidence of excitation light. The demarcation angle is the angle between the light and the optical axis; the demarcation angle is 30 degrees. The side of the free-form collimating lens 4 close to the scintillator 2 is a spherical surface; the spherical center of the spherical surface is the second focal point of the ellipsoidal reflector 1; that is, the inner side of the free-form collimating lens 4 is designed as a spherical surface, and the spherical center is at the light source; the light rays are not changed after passing through the spherical surface. The scintillator 2 is a cuboid light source; the light on the side is collected by the ellipsoidal reflector 1 and focused in front of the exit surface. The small-angle light rays are collimated by the free-form collimating lens 4, and the large-angle light rays are collimated by the free-form collimating reflector cup 3. The square light-emitting surface is defined in the x-y plane, and the z-axis is the direction of the optical axis. The inner light rays of the point light source are regarded as small-angle light rays, and the outer light rays are regarded as large-angle light rays; specifically, when the angle between the light rays and the optical axis is 30 degrees, the light rays are critical light rays. The light-emitting spectrum of the scintillator 2 has a certain range and a peak wavelength, and the present application defines the spectral range of the light source and gives the highest weight to the peak wavelength for simulation. 30° when the angle between the light rays and the optical axis is 30 degrees, the light rays are critical light rays. The light-emitting spectrum of the scintillator 2 has a certain range and a peak wavelength, and the present application defines the spectral range of the light source and gives the highest weight to the peak wavelength for simulation.

[0033] The free-form collimating lens 4 is obtained by cutting a hollow cube aligned with the rotation body of the collimating lens free-form generatrix; the face diagonal size of the hollow cube is the distance between the endpoints of the collimating lens free-form generatrix; the collimating lens free-form generatrix is obtained by weighted superposition of the intersection points of the first straight line and the transmission free-form generatrix; the first straight line is determined according to the demarcation angle; and the transmission free-form generatrix is determined by the scintillator 2 and the refraction law.

[0034] The design method of the free-form collimating lens 4 is as follows:

[0035] Step 1: The square light-emitting surface is regarded as a plurality of point light sources. Take a row of point light sources along the diagonal direction of the square as a design unit.

[0036] Step 2: Each two symmetrical point light sources in the row are reversely extended along the critical light ray propagation direction to obtain intersection points. Take the distance between the two symmetrical point light sources as the diameter of a circle to form a small circular area light source. The circular area light source can be regarded as the cross section of the point light source at the intersection point after a certain distance of propagation; different areas correspond to the cross sections of point light sources at different positions.

[0037] Step 3: Treat these intersection points as new point light sources. Take any one of these point light sources and distribute its outgoing rays at equal angles within the range of -30° to 30°. Determine the lens aperture and its distance from the emitting surface. At this point, the lens (x, y, z) coordinates corresponding to the edge rays emitted at ±30° can be determined. Based on the vector form of the law of refraction and the iterative relationship between adjacent sampling points, the collimated outgoing position coordinates of each ray can be solved, and then the generatrix of the transmission freeform surface can be fitted. Repeat the above steps to obtain the generatrix of the transmission freeform surface corresponding to all newly defined point light sources.

[0038] The vector form of the law of refraction is expressed as: .in For the refraction vector, Let be the incident vector. It is the unit vector of the normal.

[0039] Step 4, draw a straight line , The range is determined by the dividing angle, the same The coordinates of the intersection point of the line with the value and the generatrix of the nth freeform transmission surface are ( These intersection points are weighted and superimposed, with the weights decreasing from the outside to the inside, to obtain the weighted generatrix of the freeform surface of the collimating lens. Using this design method, the lens can take into account the light emitted from point sources at different positions on the surface light source as much as possible, thereby achieving a better collimation effect.

[0040] Step 5: Rotate the obtained freeform collimating lens generatrix around the optical axis by 360°, and then cut it with a hollow cube whose diagonal dimension is the distance between the endpoints of the generatrix, to obtain the freeform collimating lens entity.

[0041] The free curved surface collimating lens 4 is obtained by cutting a hollow cube with a combined body; the edge length size of the hollow cube is the distance between the end points of the collimating lens free curved surface generatrix; the combined body is obtained by combining a plurality of free curved surface collimating column lens entities; the free curved surface collimating column lens entity is obtained by translating the transmission free curved surface generatrix along a direction perpendicular to the angle of the design unit; the transmission free curved surface generatrix is determined by the scintillator 2 and the refraction law; the design unit is a row of point light sources set at an angle along the scintillator 2. That is, a row of point light sources along the x-axis, the y-axis, an angle of 45 degrees with the x-axis, an angle of 30 degrees with the x-axis, and the like are taken as a design unit, and the more different angles of the design unit taken, the better the collimating effect. The transmission free curved surface generatrix is translated along a direction perpendicular to the angle of these design units, such as the design unit along the x-axis is translated along the y-axis direction, the design unit along the y-axis is translated along the x direction, the design unit along an angle of 45 degrees with the x-axis is translated along an angle of -45 degrees with the x-axis, and the like. The combined body obtained finally is the free curved surface collimating column lens entities translated by these different design units and then combined.

[0042] The second design method of the free curved surface collimating lens 4 is as follows:

[0043] Step 1, a row of point light sources along the x direction of the square area light source is taken as a design unit, and steps 2 to 4 of the first design method are repeated to obtain the lens free curved surface generatrix.

[0044] Step 2, the generatrix is translated along the y-axis in the x-y plane to obtain a free curved surface collimating column lens entity.

[0045] Step 3, a row of point light sources along other directions of the square area light source is taken as a design unit, and steps 1 and 2 are repeated to obtain a plurality of free curved surface collimating column lens entities. The more different directions of the design unit taken, the better the collimating effect.

[0046] Step 4, the free curved surface collimating column lens entities obtained by the design method of steps 1 to 3 are combined into a whole, and then a hollow cube with an edge length size of the distance between the end points of the generatrix is used to cut the whole to obtain the designed free curved surface collimating lens 4.

[0047] The free curved surface collimating reflector cup 3 is obtained by rotating a collimating light-emitting cup free curved surface generatrix around an optical axis; the collimating light-emitting cup free curved surface generatrix is obtained by weighted superposition of the intersection points of a second straight line and a reflection free curved surface; the second straight line is determined according to the demarcation angle; and the reflection free curved surface is determined by the scintillator 2 and the reflection law.

[0048] The design steps of the free curved surface collimating reflector cup 3 are as follows:

[0049] Step 1, taking the square light-emitting surface as a plurality of point light sources, taking a row of point light sources along the diagonal direction of the square as a design unit, setting the free curved collimating reflector cup aperture, determining the (x, y, z) coordinates of the reflector cup incident edge, that is, the coordinates corresponding to the maximum angle ±90° light incident.

[0050] Step 2, randomly taking one of the point light sources, and equally distributing the large-angle outgoing light rays. According to the vector form of the reflection law and the iterative relationship between the adjacent two sampling points, the position coordinates of each collimated light ray can be solved, and then the reflection free curved surface generatrix is fitted, and the above steps are repeated to obtain the reflection free curved surface generatrix corresponding to each point light source under the aperture.

[0051] The vector form of the reflection law is represented as: , wherein is the reflected light.

[0052] Step 3, making a straight line , The range of the straight line is determined by the demarcation angle, and the intersection coordinates of the straight line with the mth reflection free curved surface are (x, y, z). , and the intersection coordinates of the straight line with the mth reflection free curved surface are (x, y, z). The intersection points are weighted and superimposed to obtain the weighted collimating reflector free curved surface generatrix.

[0053] Step 4, rotating the obtained collimating reflector free curved surface generatrix around the optical axis to obtain the designed free curved collimating reflector cup entity.

[0054] The free curved surface is designed for collimation of divergent light beams. The free curved surface refers to a curve obtained by complexly changing and then to a surface. The initial structure can be gradually approached from a spherical surface or a non-spherical surface, or point clouds obtained by ray tracing are fitted to a curved surface. The free curved surface has great design freedom, which can not only effectively improve the light energy utilization rate, but also control the light angle and other physical quantities, reduce the number and weight of optical system units, redistribute the outgoing light of the light source, and realize functions that traditional optical devices cannot realize.

[0055] The side surface of the scintillator 2 also emits light, so the side light beam also needs to be collected to improve the energy utilization rate. The present application adopts an ellipsoidal reflector 1 to collect and focus the side light. The ellipsoidal reflector 1 is a solid of revolution formed by rotating a part of an elliptical line around a central axis. It is a kind of reflector that can converge light to a point. The point light source is placed above one focus, and the light emitted therefrom is converged to another focus. Its main function is to improve the utilization efficiency of the light source.

[0056] The application provides a light beam collimation system for scintillator light emission, which is composed of an ellipsoidal reflector 1, a free-form surface collimation lens 4 and a free-form surface collimating reflector cup 3. The ellipsoidal reflector 1 focuses the light emitted from the side of the scintillator 2 to a positive light emission surface, and all the light rays are collimated through the free-form surface collimation lens 4 and the free-form surface collimating reflector cup 3. Meanwhile, the application provides two design methods of the free-form surface collimation lens 4 and a design method of the free-form surface collimating reflector cup 3. The system can effectively reduce the divergence angle of the light emitted by the scintillator 2, achieve good collimation effect, collect the light emitted from all surfaces of the scintillator 2 and has high energy utilization rate, and provides a new idea for the shaping of the light beam emitted by the scintillator 2. The application can well collimate and shape the light beam emitted by the scintillator 2 and effectively reduce the divergence angle. Meanwhile, the application provides two design methods of the free-form surface collimation lens 4 for small-angle light collimation and a design method of the free-form surface collimating reflector cup 3 for large-angle light collimation, and the ellipsoidal reflector 1 is used to converge the light emitted from the side of the scintillator 2. The application can shape the light beam emitted by the scintillator 2, obtain a collimated light beam with a small divergence angle, is conducive to long-distance transmission, can make the light better collected and utilized, improve the energy utilization rate and imaging resolution. On the other hand, the improvement of the energy utilization rate can reduce the radiation dose while providing the same imaging quality, reduces the radiation to the human body, provides a possibility for the subsequent use of low-dose medical imaging equipment, biological treatment, non-destructive testing, security check and high-energy particle detection experiments.

[0057] Fig. 3 (a) is a schematic diagram of the transmission free-form surface generatrix corresponding to a plurality of newly composed point light sources when the free-form surface collimation lens is designed according to the embodiment of the application. Fig. 3 (b) is a schematic diagram of weighted superposition of points on the generatrix. Fig. 3 (c) is a schematic diagram of the first kind of exit surface of the free-form surface collimation lens according to the embodiment of the application. Fig. 3 (d) is a schematic diagram of the first kind of entrance surface of the free-form surface collimation lens according to the embodiment of the application. Fig. 3 (e) is a schematic diagram of the second kind of exit surface of the free-form surface collimation lens according to the embodiment of the application.

[0058] Fig. 4 (a) is a schematic diagram of the reflection free-form surface generatrix corresponding to point light sources at different positions when the free-form surface collimating reflector cup is designed according to the embodiment of the application. Fig. 4 (b) is a schematic diagram of weighted superposition of points on the generatrix. Fig. 4 (c) is a side view of the free-form surface collimating reflector cup according to the embodiment of the application. Fig. 4 (d) is an oblique view of the free-form surface collimating reflector cup according to the embodiment of the application.

[0059] The emission peak wavelength of the CsI scintillator 2 is 565 nm, the spectral range of the light source is 450 nm-650 nm, and the maximum weight is taken for the emission peak wavelength 565 nm for simulation.

[0060] The light emitted from the side of the scintillator 2 is focused by the ellipsoidal reflector 1 to the front of the light emitting surface. The small-angle light emitted from the scintillator 2 is collimated by the free-form collimating lens 4, and the large-angle light is collimated by the free-form collimating reflector cup 3.

[0061] The ellipsoidal reflector 1 collects the light emitted from the side of the scintillator 2:

[0062] Figure 2(a) is a schematic diagram of the light from the first focal point f1 of the ellipsoidal reflector converging at the second focal point f2 of the ellipsoidal reflector after being reflected by the reflector according to an embodiment of the present application. The divergent light emitted from the side of the scintillator is focused by the ellipsoidal reflector to the front of the scintillator, and is collimated by the subsequent free-form collimating lens and free-form collimating reflector cup. Figure 2(b) is a perspective view of the ellipsoidal reflector, which has a radius of 34.5 mm at the light outlet and a quadratic surface coefficient of -0.0204. Figure 2(c) is a front view of the ellipsoidal reflector.

[0063] Two design methods of the free-form collimating lens:

[0064] Figures 3(a) and 3(b) are schematic diagrams of the design process of the free-form collimating lens. In Figure 3(a), O （-8） O8is a point light source taken on a design unit. In the present application, the number of selected point light sources is 15-20, and the number of selected light emitting points can be selected as required. O'~O'8is a newly formed point light source. The line segment O （-8） O8is a small part of a circular surface light source composed of the diameter of a circle. The small part of the circular surface light source can be regarded as the cross section of the point light source O'8after propagating a certain distance. Different areas correspond to the cross sections of point light sources at different positions.

[0065] The lens coordinate point corresponding to the edge light of the center point light source is set as (0, 30, 64). The light is collimated and emitted, and the unit directional vector of the emitted light is known. According to the vector form of the refraction law, the normal vector of the emission point is known, and the tangent slope of the emission point is obtained. The tangent slope of the emission point can also be approximately represented by the coordinates of the adjacent two points. The position coordinates of each light collimated and emitted can be solved by using the iterative relationship between the adjacent two sampling points, and the transmission free-form surface generatrix is fitted. L~L8is the transmission free-form surface generatrix corresponding to O'~O'8.

[0066] Figure 3(b) is a schematic diagram of the weighted superposition of multiple transmission free-form surface generatrices. G1~G8are the intersection points of the straight lines and the transmission free-form surface generatrix. The critical angle is 30°, so the critical value of k1 is 0.58. The intersection coordinates of the straight line with the same k1 value and the transmission free-form surface generatrix are weighted and superimposed to obtain a point coordinate on the designed transmission free-form surface generatrix. Set The weighting coefficient is Then , Because the outer bus is corresponding to the larger area light source, the weight is decreased from the outer to the inner, and the above steps are repeated to obtain the coordinates of all points on the designed transmission free-form bus. FIG. 3(c) and FIG. 3(d) are free-form collimating lenses obtained by the above design method.

[0067] FIG. 3(e) is a free-form collimating lens obtained by the above design method. In the design method, one row of point light sources along the y direction of the square surface light source and along the diagonal direction of the square surface light source are taken as a design unit, and the steps 1 in the above design method are repeated to obtain the transmission free-form bus corresponding to different design units. The more the design units in different directions are taken, the better the collimating effect is. The bus is translated to obtain a plurality of free-form collimating column lens entities, and the column lens entities are superimposed and cut to obtain the free-form collimating lens entity obtained by the above design method 2. The free-form collimating lenses designed by the two methods are both 34 mm in length and width, and the inner surfaces of the lenses are spherical surfaces.

[0068] Design of free-form collimating reflector cup:

[0069] FIG. 4(a) and FIG. 4(b) are schematic diagrams of the design process of the free-form collimating reflector cup. One row of point light sources along the diagonal direction of the square is taken as a design unit, and the number of point light sources selected in the embodiment is 15-20. The number of selected light emitting points can be selected according to needs.

[0070] The aperture of the free-form collimating reflector cup is set, and the edge coordinates of the reflector cup are determined, that is, the coordinates of the maximum angle of incidence are (0, 35, 0). The unit direction vector of the outgoing light is known, and according to the vector form of the reflection law, the normal vector of the outgoing point is known, and then the tangent slope of the outgoing point is obtained. The tangent slope of the outgoing point can be approximately represented by the coordinates of the adjacent two points, and the position coordinates of each light collimation exit can be solved by using the iterative relationship between the adjacent two sampling points, and then the reflection free-form bus is fitted. The reflection free-form bus corresponding to each point light source under the aperture is obtained by repeating the above steps. FIG. 4(a) l8~l （-8） The point light source o （-8） corresponds to the reflection free-form bus. The smaller the exit aperture of the point light source close to the incident edge of the reflector cup is.

[0071] FIG. 4(b) is a schematic diagram of superimposing a plurality of reflection free-form buses. g1~g8 are straight lines The intersection point of the reflection free-form surface generatrix. The intersection point coordinates of the straight line with the same k2 value and the free-form surface generatrix are weighted and superimposed to obtain a point coordinate on the designed free-form surface generatrix. Let be the weighting coefficient, then , Repeat the above steps to obtain the coordinates of all points on the designed free-form surface collimating reflector generatrix. Rotate the obtained generatrix around the optical axis to obtain the designed free-form surface collimating reflector entity. FIG. 4(c) and FIG. 4(d) are entity diagrams of the free-form surface collimating lens, with an entrance aperture radius of 36 mm and an exit aperture radius of 131 mm.

[0072] FIG. 6 is a comparison diagram of the light intensity distribution before and after shaping by the collimating system. FIG. 6(a) reflects the light intensity distribution of light with different exit angles of the 16 mm x 16 mm x 5 mm scintillator. FIG. 6(b) reflects the light intensity distribution of light with different exit angles after the light beam is shaped by the system composed of the free-form surface collimating lens, the free-form surface collimating reflector, and the ellipsoid reflector obtained by the design method 1. FIG. 6(c) reflects the light intensity distribution of light with different exit angles after the light beam is shaped by the system composed of the free-form surface collimating lens, the free-form surface collimating reflector, and the ellipsoid reflector obtained by the design method 2. It can be seen from the comparison of FIG. 6(a) and FIG. 6(b), FIG. 6(c) that the light with large divergence angle is significantly reduced and the light intensity of the light with small angle is significantly improved after shaping. It is proved that the present application can effectively reduce the divergence angle of the emitted light, has good collimation effect, and well realizes the shaping of the light beam emitted by the scintillator.

[0073] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between the embodiments can be referred to each other.

[0074] The principles and implementation manners of the present application are described by using specific examples in this paper. The above embodiment description is only used to help understand the system and its core idea of the present application; at the same time, according to the idea of the present application, the specific implementation manner and application range will be changed by the general technical personnel in the field. In conclusion, the content of the specification should not be understood as the limitation of the present application.

Claims

1. A scintillator beam collimation system, characterized in that, include: Ellipsoidal reflector, freeform collimating reflector cup, and freeform collimating lens; The scintillator is positioned at the first focal point of the ellipsoidal mirror; The ellipsoidal reflector is used to converge the light emitted from the side of the scintillator to the second focal point of the ellipsoidal reflector; the freeform collimating reflector is connected to the ellipsoidal reflector; the freeform collimating reflector is used to collimate the light emitted by the scintillator that exceeds the boundary angle and the light converged by the ellipsoidal reflector; the freeform collimating lens is used to collimate the light emitted by the scintillator that is less than the boundary angle and the light converged by the ellipsoidal reflector.

2. The scintillator beam collimation system according to claim 1, characterized in that, The ellipsoidal reflector, the scintillator, the freeform collimating reflector cup, and the freeform collimating lens are located on the same optical axis.

3. The scintillator beam collimation system according to claim 1, characterized in that, The ellipsoidal reflector has a small hole on the side away from the scintillator; the small hole is used for the incident light of the excitation light.

4. The scintillator beam collimation system according to claim 1, characterized in that, The dividing angle is the angle between the ray and the optical axis; the dividing angle is 30 degrees.

5. The scintillator beam collimation system according to claim 1, characterized in that, The side of the freeform collimating lens closest to the scintillator is spherical; the center of the sphere is the second focal point of the ellipsoidal reflector.

6. The scintillator beam collimation system according to claim 1, characterized in that, The scintillator is a cuboid light source.

7. The scintillator beam collimation system according to claim 6, characterized in that, The freeform collimating lens is obtained by cutting a hollow cube into the generatrix of the collimating lens's freeform surface; the face diagonal dimension of the hollow cube is the distance between the endpoints of the generatrix of the collimating lens's freeform surface; the generatrix of the collimating lens's freeform surface is obtained by weighted superposition of the intersection points of a first straight line and the generatrix of the transmission freeform surface; the first straight line is determined according to the dividing angle; the generatrix of the transmission freeform surface is determined by the scintillator and the law of refraction.

8. The scintillator beam collimation system according to claim 6, characterized in that, The freeform collimating lens is obtained by cutting the combined body using a hollow cube; the edge length of the hollow cube is the distance between the endpoints of the generatrix of the freeform collimating lens; the combined body is obtained by merging multiple freeform collimating cylindrical lens entities; the freeform collimating cylindrical lens entity is obtained by translating the generatrix of the transmission freeform surface along a direction perpendicular to the angle of the design unit; the generatrix of the transmission freeform surface is determined by the scintillator and the law of refraction; the design unit is a row of point light sources along a set angle of the scintillator.

9. The scintillator beam collimation system according to claim 6, characterized in that, The freeform collimating reflector is obtained by rotating the generatrix of the collimating reflector's freeform surface around the optical axis; the generatrix of the collimating reflector's freeform surface is obtained by weighted superposition of the intersection points of the second straight line and the reflecting freeform surface; the second straight line is determined according to the dividing angle; the reflecting freeform surface is determined by the scintillator and the law of reflection.

Images