CN1226653C

CN1226653C - Array angular beam expander

Info

Publication number: CN1226653C
Application number: CN 03128299
Authority: CN
Inventors: 赵斌
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2003-07-08
Filing date: 2003-07-08
Publication date: 2005-11-09
Anticipated expiration: 2023-07-08
Also published as: CN1487328A

Abstract

The present invention discloses an array angular beam expander. The angular beam expander is a face array which is composed of n identical angular beam expander assemblies, wherein n is larger than and equal to two; each assembly is composed of a positive microlens and a negative microlens; the focal length and an interval of the positive and the negative lenses meet that the integral focal power of each lens set is zero; distance between the center of any microlens and the center of an adjacent microlens in the array is equal. The thickness of the angular beam expander is decided on thickness between the positive microlens and the corresponding negative microlens. Because the dimension of single microlens is small, even if angular magnification multiple is large, the thickness of single microlens can not be caused to be large. Simultaneously, no matter how large is the hole diameter of an incident beam, complete incident light can be contained so long as increasing the quantity of the microlenses and enlarging the area of the array in theory; the angular magnification multiple is invariant, and the integral thickness of the angular beam expander is invariant. Thus, the thickness of the present invention is smaller than the existing angular beam expander under the condition of providing the same angular magnification multiple and the same hole diameter of the incident light.

Description

A kind of array type angle beam expander

Technical field

The present invention relates to a kind of optical component, be specifically related to a kind of array type angle beam expander.

Background technology

The function of angle beam expander is the exit plane light that the planar light of a certain direction incident is transformed into other direction, and the angle of incident light, emergent light and optical axis satisfies fixing enlargement factor.

Generally, the angle beam expander is to constitute (as shown in Figure 1) by one positive one negative two lens or lens combination that focus overlaps, when a branch of planar light is incident on the positive lens on the left side with angle θ, it is focused on the focal plane of positive lens, and convergent point to the distance of optical axis is f1 * θ, because the focus of positive lens overlaps with the focus of negative lens, therefore, this converging beam will become a planar light, and its direction is f1 * θ/f2=M * θ after the negative lens refraction.

For existing angle beam expander, expect big angle enlargement factor M, the focal distance ratio of two lens before and after just must increasing, yet, for common lens, because the restriction of grinding process technique method, the lens surface curvature radius can not be very little, generally all greater than 5 millimeters (or these magnitudes), therefore, the focal length of back one lens can not be very little.On the other hand, when the desired light beam aperture d of optical system is big, guarantee logical light, at least require lens radius of curvature greater than half of light beam aperture, further contemplate the factor of plane of refraction aberration, generally require the refractive surface radius-of-curvature (for example to require r2＞10 * d) usually much larger than light beam aperture, like this, for high-aperture beam, the focal distance f 2 of negative lens is just quite big, at this moment, has only the focal distance f 1 by increasing last lens to increase angle enlargement factor M, and the distance (T=f1-f2) between so positive negative lens must increase, and causes the total system size to increase.

Summary of the invention

The object of the present invention is to provide a kind of micro lens array type angle beam expander, this angle beam expander can have thin thickness when having big angle enlargement factor and big clear aperature.

A kind of array type of the present invention angle beam expander, the positive lenticule and the negative lenticule that are overlapped by optical axis constitute, it is characterized in that: this angle beam expander constitutes the face array by n identical angle beam expander assembly, n 〉=2, each assembly is made of positive lenticule and negative lenticule, and its whole focal power that should satisfy each lens combination that is made of positive lenticule and corresponding negative lenticule at interval of the focal length of positive and negative lens and its is zero; Distance in the array between the center of arbitrary lenticular center and contiguous microlens equates.

When a branch of wide-aperture planar light incided on the beam expander of angle of the present invention, the positive micro lens array of its front surface was divided into the planar light beam of a series of small-bores.The light beam of these small-bores incides on the negative lenticule of rear surface after focusing on through positive lenticule, becomes the littler planar light beam in aperture again after negative lenticule is dispersed.Because these small-bore light beams from each negative lenticule outgoing have identical direction, therefore they synthesize the big planar light beam in a beam orifice again, only its direction is different with the direction of plane of incidence light beam, and emergence angle and incident angle satisfy certain multiple relation, so just realized that the large aperture planar light with a direction is transformed to the large aperture planar light beam of another direction, promptly this device has been finished the angular transformation of large aperture planar light beam.The thickness of micro lens array type angle beam expander is by the thickness decision between the negative lenticule of positive lenticule and correspondence, because it is single lenticular small-sized, so even the angle enlargement factor is very big, can not cause its thickness very big, simultaneously yet, no matter it is much that the aperture of incident beam has, as long as increase lenticular number, enlarge the area of array in theory, just can hold whole incident lights, and the angle enlargement factor is constant, and the thickness of device integral body is constant.Therefore, providing under same angle enlargement factor and the same incident light aperture condition, the thickness of this device is much smaller than existing angle beam expander.

Description of drawings

Fig. 1 is an angle beam expander functional schematic; (a) plane wave normal incidence; (b) plane wave oblique incidence; Among the figure: f1 is the focal length of positive lens, and f2 is the focal length of negative lens, and T is the interval of positive negative lens, and F is the focus of lens.

Fig. 2 is the structural representation of a kind of one chip micro lens array type angle beam expander; Among the figure: the 1st, the positive lens plane of refraction, the 2nd, negative lens plane of refraction, ab are the large aperture planar light beams of incident, and a ' b ' is the small-bore planar light beam of outgoing, open circles is represented the focal point F 1 of positive lens (left surface), and black circle is represented the focal point F 2 on negative lens (right surface).

Fig. 3 is the space structure synoptic diagram of micro lens array type angle beam expander;

Fig. 4 is the structural representation of a kind of double-disk micro lens array type angle beam expander;

Fig. 5 is the distribution form synoptic diagram at each lenticule center in the beam expander of micro lens array type angle;

Fig. 6 is an example of the present invention synoptic diagram.

Embodiment

As Fig. 2, shown in Figure 3, the present invention combines a positive lenticule 1 with a negative lenticule 2, constitute an angle beam expander assembly; Again a large amount of identical angle beam expander arrangements of components are become a face array (Fig. 2), thereby form a kind of new optical device.Lenticular singularity is in this device, is zero by the whole focal power of single positive lenticule and the corresponding lenticule group that negative lenticule constituted.The advantage of this device is to have big angle enlargement factor, big clear aperature and thin thickness simultaneously.

This device has following feature on physical dimension:

1) each positive lenticule all has the negative lenticule of a correspondence, and their optical axis overlap (normal that optical axis refers to lenticule centre of surface point).

2) each whole focal power that is made of positive lenticule and negative lenticule is zero.The computing method of focal power are:

＝1/f1-1/f2+T/f1/f2

Because whole focal power is zero, so T=f1-f2, just just lenticular focus overlaps with negative lenticular focus.The focal point F 1 of Fig. 2 hollow core circle positive lenticule of expression (left surface), black circle are represented the focal point F 2 on negative lenticule (right surface), and their center overlaps, and the expression focus overlaps.

3) under the situation that satisfies above two conditions, positive lenticule and negative lenticule can be produced on the two sides, front and back of same sheeting, and at this moment, single plane of refraction is exactly lens; Also can be produced on two sheetings, the two sides, front and back of each block of material all is made into plane of refraction, and lens of the common composition of these two planes of refraction then, allow two micro lens arrays put relatively, form an integral body.

Among Fig. 2, positive lens is a protruding plane of refraction, and negative lens is a recessed plane of refraction.The advantage of this form is that compactness, physical dimension are not subject to ectocine and change, thereby stable performance.

Among Fig. 4, positive negative lens is made in respectively on two thin plates, and the benefit of this form is to have increased the plane of refraction number, helps aberration correction, improves image quality.

4) positive lenticule and negative lenticular surface can be sphere or aspheric surface.The design of aspheric surface should make that under specific angle enlargement factor and clear aperature, when incident light was plane wave, the wave front of emergent light and the deviation of plane wave were as far as possible little.

5) distribution form of array, under the equidistant condition between the center of satisfying arbitrary lenticular center and contiguous microlens, can for equilateral triangle (Fig. 5 a) or the square (Fig. 5 b)

Fig. 6 is a little telescopical example of being made up of two planes of refraction, wherein, and convex surface radius=0.400mm, concave=0.162mm, thickness=0.70mm, aperture=0.40mm, material refractive index n=1.5.Among the figure, ab is the normal incidence planar light beam, and cd oblique incidence planar light beam, a ' b ' are the normal emergence planar light beam, and c ' d ' is the exit plane light beam tiltedly.

The present invention can use in the optical instrument of many classifications as a kind of new universal optical element.

The principle of using in any concrete optical instrument is: the incident beam of array angle beam expander must be a plane wave.

Claims

1, a kind of micro lens array type angle beam expander, the positive lenticule and the negative lenticule that are overlapped by optical axis constitute, it is characterized in that: this angle beam expander constitutes the face array by n identical angle beam expander assembly, n 〉=2, angle beam expander assembly constitutes by positive lenticule (1) and negative lenticule (2), and positive and negative lenticular focal length and the whole focal power that should satisfy each lens combination that is made of positive lenticule and corresponding negative lenticule at interval thereof are zero; Distance in the array between the center of arbitrary lenticular center and contiguous microlens equates.

2, angle according to claim 1 beam expander, it is characterized in that: described positive lenticule (1) and negative lenticule (2) constitute by single plane of refraction.

3, angle according to claim 1 beam expander, it is characterized in that: described positive lenticule (1) and negative lenticule (2) constitute by two planes of refraction.