TWI797684B - Imaging system - Google Patents

Abstract

An imaging system includes a beam splitter, a first lens unit, a second lens unit, a third lens unit, and a fourth lens unit. The first lens unit is with refractive power. The second lens unit is with refractive power. The third lens unit is with refractive power. The fourth lens unit is with positive refractive power. The fourth lens unit, the beam splitter, and the first lens unit are arranged in order from an projection side to an image source side along a first axis. The second lens unit, the beam splitter, and the third lens unit are arranged in order along a second axis. The first axis intersects the second axis.

Description

imaging system

The present invention relates to an imaging system.

Micro-projection imaging systems have been widely used in head-mounted displays, and will be used in new technologies such as AR, VR, and MR in the future. However, most imaging systems with traditional architectures use axisymmetric lenses. It is not easy to control the effective focal length of the horizontal axis image and the vertical axis image. Heavy weight is not conducive to long-term wear. Therefore, another imaging system with a new structure is required to satisfy the requirements of small size, light weight and effective focal length that can control the horizontal axis image and the vertical axis image at the same time.

In view of this, the main purpose of the present invention is to provide an imaging system. A beam splitter is introduced into the optical path of the imaging system to reduce the volume and weight of the imaging system. In addition, a cylindrical lens is used to control the horizontal axis image and the vertical axis image. effective focal length.

The imaging system of the present invention includes a beam splitter, a first lens unit, a second lens unit, a third lens unit and a fourth lens unit. The first lens unit has refractive power. The second lens unit has refractive power. The third lens unit has refractive power. The fourth lens unit has positive refractive power. The fourth lens unit, the beam splitter and the first lens unit are arranged in sequence along a first axis from a projection side to an image source side. Second lens unit, beam splitter and third lens unit arranged in sequence along a second axis. The first axis intersects the second axis.

Wherein the first lens unit includes a first lens, the second lens unit includes a second lens, the third lens unit includes a third lens, the fourth lens unit includes a fifth lens, the fifth lens has positive refractive power, and the first lens unit includes a third lens. The lens, the second lens and the third lens are cylindrical lenses, and the light from an image source passes through the first lens unit, the beam splitter, the second lens unit, the beam splitter, the third lens unit, the beam splitter, and the fourth lens in sequence unit, and finally projected on a projection plane.

Wherein the second lens unit may further include a first polarization state changing structure, the first polarization state changing structure is arranged between the beam splitter and the second lens, the third lens unit may further include a second polarization state changing structure, The second polarization state changing structure is disposed between the beam splitter and the third lens.

Wherein the first lens, the second lens and the third lens have positive refractive power, and the second lens and the third lens may further include a high reflection film coating or pasting on a cylindrical surface.

The third lens unit may further include a fourth lens with positive refractive power, and the third lens is located between the second polarization state changing structure and the fourth lens.

Wherein the fourth lens is a cylindrical lens, and the second lens and the fourth lens may further include a high reflective film coated or pasted on a cylindrical surface.

1.72；0.5

PBSH/PBSL<1；1.5

PBSL/PBST

2.3；1

PBSH/PBST

1.7；1.9

OPL/PBSL

3；2.6

OPL/PBSH

4.2；3.6

OPL/PBST

5.7；0.01

BFL/OPL

0.04；0.05

BFL/f

0.15；0.25

IMGH/f

0.45；0.1

IMGH/OPL

0.17；1.4

3fy/f

2.3；0.5

2fx/f

0.9；0.9

1fy/f

1.7；0.52

1fy/3fy

0.89；0.3

2fx/3fy

0.5；3fy>1fy；1.7

f_FLG/f

3；其中，PBSL為成像系統 之一長度，亦即投影側至影像源側在第一軸線上之距離，PBSH為成像系統之一高度，亦即第二透鏡單元遠離分光鏡之一側至第三透鏡單元遠離分光鏡之一側在第二軸線上的距離，PBST為分光鏡之一厚度，亦即分光鏡之投影側面至影像源側面在第一軸線上的距離，OPL為成像系統之一光程長度，BFL為最靠近影像源側之透鏡之一影像源側面至一影像源沿著第一軸線之一間隔，f為成像系統之一有效焦距，IMGH為成像系統之一半像高，1fy為第一透鏡單元之一Y軸方向有效焦距，2fx為第二透鏡單元之一X軸方向有效焦距，3fy為第三透鏡單元之一Y軸方向有效焦距，f為成像系統之一有效焦距，f_FLG為第四透鏡單元之一有效焦距，以下本發明表格中所示的fx、fy有效焦距方向須以右手定則來判斷，中指表示為光軸方向並定義為Z軸，食指定義為X軸，拇指定義為Y軸，此三軸互相垂直；以第一透鏡單元為例，其光軸沿第一軸線由影像源側朝投影側方向，因此其Z軸朝左，以右手定則判斷則其Y軸沿第二軸線朝上，X軸朝一第三軸線朝內；第二透鏡單元其光軸沿第二軸線往遠離分光鏡的方向指向上方，所以Z軸朝上，其餘X軸和Y軸同上述判斷；第三透鏡單元的光軸沿第二軸線往遠離分光鏡的方向指向下方，所以Z軸朝下，其餘X軸和Y軸同上述判斷。 The imaging system meets at least one of the following conditions: 1<PBSL/PBSH

1.72; 0.5

PBSH/PBSL<1; 1.5

PBSL/PBST

2.3;1

PBSH/PBST

1.7; 1.9

OPL/PBSL

3;2.6

OPL/PBSH

4.2; 3.6

OPL/PBST

5.7; 0.01

BFL/OPL

0.04; 0.05

BFL/f

0.15; 0.25

IMGH/f

0.45; 0.1

IMGH/OPL

0.17; 1.4

3fy/f

2.3; 0.5

2fx/f

0.9; 0.9

1fy/f

1.7; 0.52

1fy/3fy

0.89; 0.3

2fx/3fy

0.5; 3fy>1fy; 1.7

f _FLG /f

3; Among them, PBSL is the length of the imaging system, that is, the distance from the projection side to the image source side on the first axis, and PBSH is the height of the imaging system, that is, the side of the second lens unit away from the beam splitter to the first axis The distance of the three-lens unit away from one side of the beam splitter on the second axis, PBST is the thickness of the beam splitter, that is, the distance from the projected side of the beam splitter to the side of the image source on the first axis, and OPL is one of the imaging systems Optical path length, BFL is the distance between one image source side of the lens closest to the image source side and an image source along the first axis, f is an effective focal length of the imaging system, IMGH is a half-image height of the imaging system, 1fy is the effective focal length of one of the first lens units in the Y-axis direction, 2fx is the effective focal length of one of the second lens units in the X-axis direction, 3fy is the effective focal length of one of the third lens units in the Y-axis direction, and f is one of the effective focal lengths of the imaging system, f _FLG is one of the effective focal lengths of the fourth lens unit. The directions of fx and fy effective focal lengths shown in the following table of the present invention must be judged by the right-hand rule. The middle finger represents the direction of the optical axis and is defined as the Z axis, and the index finger is defined as the X axis. , the thumb is defined as the Y axis, and these three axes are perpendicular to each other; taking the first lens unit as an example, its optical axis is along the first axis from the image source side to the projection side, so its Z axis is facing left, judging by the right-hand rule. The Y axis faces upward along the second axis, and the X axis faces inward toward a third axis; the optical axis of the second lens unit points upward along the second axis away from the beam splitter, so the Z axis faces upward, and the remaining X and Y axes The same judgment as above; the optical axis of the third lens unit points downward along the second axis away from the beam splitter, so the Z-axis faces downward, and the rest of the X-axis and Y-axis are the same as the above judgment.

The imaging system satisfies the condition: 2fx≒1/((1/3fy)+(1/1fy)); or the condition: 2fx=(3fy×1fy)/(3fy+1fy); among them, 1fy is the first lens unit - an effective focal length in the Y-axis direction, 2fx is an effective focal length in the X-axis direction of one of the second lens units, and 3fy is an effective focal length in the Y-axis direction of one of the third lens units.

where the first axis is perpendicular to the second axis.

In order to make the above-mentioned objects, features, and advantages of the present invention more obvious and understandable, the following Wen Te cites preferred embodiments and explains in detail with the accompanying drawings.

1, 2, 3: Imaging system

LG11, LG21, LG31: first lens unit

LG12, LG22: Second lens unit

LG13, LG23: Third lens unit

FLG1, FLG2, FLG3: fourth lens unit

L11, L21: first lens

L12, L22: second lens

L13, L23: third lens

L14: Fourth lens

L15, L25: fifth lens

PBS1, PBS2: Beamsplitter

ST1, ST2: Aperture

QWP11, QWP21: The first polarization state changing structure (the first quarter-wave retarder)

QWP12, QWP22: Second Polarization State Changing Structure (Second Quarter Wavelength Retardation)

PS1, PS2: projection surface

IS1, IS2: image source

AX11, AX21: first axis

AX12, AX22: second axis

S11, S21: the first surface

S12, S22: second surface

S13, S23: the third surface

S14, S24: the fourth surface

S15, S25: Bevel

X: X-axis

Y: Y-axis

Z: Z-axis

40: Optical path turning element

100: eyeball

FIG. 1 is a schematic diagram of the lens configuration and optical path of the first embodiment of the imaging system according to the present invention.

Figures 2A, 2B, and 2C are Field Curvature, Distortion, and Modulation Transfer Function diagrams of the first embodiment of the imaging system according to the present invention.

FIG. 3 is a schematic diagram of the lens configuration of the second embodiment of the imaging system according to the present invention.

Fig. 4 is a schematic diagram of the application of the imaging system according to the present invention to AR, VR or XR.

The present invention provides an imaging system, comprising: a beam splitter; a first lens unit, the first lens unit has a refractive power; a second lens unit, the second lens unit has a refractive power; a third lens unit, the third The lens unit has a refractive power; a fourth lens unit, the fourth lens unit has a positive refractive power; wherein the fourth lens unit, the beam splitter and the first lens unit are sequentially along a first axis from a projection side to an image source side Arrangement; the second lens unit, the beam splitter and the third lens unit are sequentially arranged along a second axis; wherein the first axis intersects the second axis. In other embodiments, the beam splitter may be a polarized beam splitter, a plate beam splitter, a polarized beam splitter or a square beam, and other optical elements capable of achieving light splitting. Through the above design, it is helpful to effectively reduce the volume, effectively reduce the weight, effectively correct the aberration, and effectively extend the optical path.

Please refer to Table 1, Table 2, Table 4 and Table 5 below, of which Table 1 and Table 4 are divided into Table 2 and Table 5 are the relevant parameter tables of the aspheric surface of the aspheric lens in Table 1 and Table 4 respectively. .

Please refer to Figures 1 and 2 at the same time. The lens configuration and optical path schematic diagram of the third embodiment of the remaining imaging system are similar to the second embodiment, so its illustration is omitted, but the content about the third embodiment will still be described below The symbols of the elements in the third embodiment are continued to be used for convenience of description. Wherein the first lens units LG11, LG21, LG31 have positive refractive power, and respectively include a first lens L11, L21, L31, and the second lens units LG12, LG22, LG32 have positive refractive power, and respectively include a second lens L12, L22 . . A second surface S12, S22, S32, a third surface S13, S23, S33, a fourth surface S14, S24, S34, an inclined surface S15, S25, S35, in other embodiments the inclined surface can be set at 45 degrees.

The first lenses L11, L21, and L31 are cylindrical lenses with positive refractive power. The projection side is a plane, the side of the image source is a cylinder, the X-axis direction of the cylinder is a plane, and the Y-axis direction is a convex surface. The Y-axis direction is a spherical surface. The second lenses L12, L22, and L32 are cylindrical lenses with positive refractive power. The side facing the beam splitter is a plane, and the side not facing the beam splitter is a cylinder. The X-axis direction of the cylinder is convex and the Y-axis direction is a plane and convex surface. It is a spherical surface, and the cylindrical surface is plated or pasted with a high reflection film (not shown). The third lenses L13, L23, L33 are cylindrical lenses, The side facing the beam splitter is a plane, the side not facing the beam splitter is a cylinder, and the X-axis direction of the cylinder is a plane. The fifth lenses L15 , L25 , and L35 are aspherical lenses with positive refractive power. The projection side is concave, the image source side is convex, and both the projection side and the image source side are aspheric surfaces. First surface S11, S21, S31, second surface S12, S22, S32, third surface S13, S23, S33, fourth surface S14, S24, S34, slope S15, S25, S35 of beam splitter PBS1, PBS2, PBS3 All are planes, and the beam splitters PBS1, PBS2, and PBS3 can reflect the incident S-polarized light from the first surface S11, S21, and S31 on the 45-degree inclined planes S15, S25, and S35 to the second surface S12, S22, and S32. The incident P-polarized light can be transmitted to the fourth surface S14, S24, S34 at the 45-degree slope S15, S25, S35, or the S-polarized light incident from the second surface S12, S22, S32 can be transmitted to the 45-degree slope Reflection at S15, S25, S35 is directed to the first surface S11, S21, S31, and the incident P-polarized light can be transmitted to the third surface S13, S23, S33 at the 45-degree inclined plane S15, S25, S35, or The S-polarized light incident from the third surface S13, S23, S33 is reflected at the 45-degree inclined plane S15, S25, S35 and directed to the fourth surface S14, S24, S34, and the incident P-polarized light can be incident on the 45-degree inclined plane S15 , S25, and S35 penetrate to the second surface S12, S22, and S32. There can be an air gap or no air gap between the beam splitter PBS1, PBS2, PBS3 and the first lens L11, L21, L31, the second lens L12, L22, L32 and the third lens L13, L23, L33 (for example: cemented ) way to set. Using a cylindrical lens is beneficial to control the effective focal length and magnification of the horizontal axis image and the vertical axis image.

The X-axis and Y-axis of the first lens, the second lens, and the third lens mentioned in this manual must be judged by the right-hand rule respectively. is the Y axis, and the X, Y, and Z axes are perpendicular to each other; taking the first lens unit as an example, its optical axis is along the first axis from the image source side to the projection side, so the Z axis (middle finger) faces to the left, and the Y The axis (thumb) faces upward along the second axis, and the X-axis (index finger) faces inward toward a third axis (not shown), which is perpendicular to the first and second axes; the second lens unit optical axis is along the first The second axis points upward away from the beam splitter, so the Z axis faces upward, and the rest of the X axis and Y axis are the same as the above judgment; the optical axis of the third lens unit points down along the second axis away from the beam splitter, so the Z axis Downward, the rest of the X-axis and Y-axis are the same as the above judgment.

Through the above settings, the imaging systems 1, 2, and 3 can effectively reduce the volume, effectively reduce the weight, and effectively correct aberrations. In addition, the imaging systems 1, 2, and 3 satisfy at least one of the following conditions (1) to (20) condition:

3fy>1fy; (17)

2fx≒1/((1/3fy)+(1/1fy)) (19)

2fx=(3fy×1fy)/(3fy+1fy) (20)

Among them, PBSL is the length of the imaging systems 1, 2, and 3 in the first embodiment to the third embodiment, that is, the distance from the projection side of the imaging system to the image source side in the first axis direction, and PBSH is the first embodiment For example, in the third embodiment, a height of the imaging system 1, 2, 3, that is, the distance from the side of the second lens unit away from the beam splitter to the side of the third lens unit away from the beam splitter in the direction of the second axis , PBST is the thickness of the beam splitter PBS1, PBS2, PBS3 in the first embodiment to the third embodiment, that is, the distance between the projected side of the beam splitter and the side of the image source in the first axis direction, OPL is the imaging system 1 , an optical path length of 2, 3, BFL is one of the image source sides of the lenses L11, L21, L31 closest to the image source side to an image source IS1, IS2, IS3 along the first axis AX11, AX12, AX13 Interval, IMGH is the half-image height of one of imaging systems 1, 2, and 3, 1fy is the effective focal length in the Y-axis direction of one of the first lens units LG11, LG21, and LG31, and 2fx is the X-axis of one of the second lens units LG12, LG22, and LG32 3fy is the effective focal length of one of the third lens units LG13, LG23, LG33 in the Y-axis direction, and f _FLG is the effective focal length of one of the fourth lens units FLG1, FLG2, FLG3.

When the conditions (1)~(4), (9), (10), and (11) are met, it can help to reduce the volume of the imaging system; when the conditions (5)~(8) are met, it can help increase the The optical path length and reduced volume of the imaging system, when the conditions (12)~(16) and (18) are met, can help to control the volume of the imaging system. When the item (17) is used, it can help to shorten the distance between the first lens unit and the image source. When the conditions (19) and (20) are met, it is beneficial for the effective focal length of the X-axis and the Y-axis of the final imaging position to be the same.

The first embodiment of the imaging system of the present invention will now be described in detail. Please refer to FIG. 1 , the imaging system 1 sequentially includes an aperture ST1, a fourth lens unit FLG1, a beam splitter PBS1 and a first lens unit LG11 along a first axis AX11 from a projection side to an image source side. , the imaging system 1 sequentially includes a second lens unit LG12 , a beam splitter PBS1 and a third lens unit LG13 along a second axis AX12 . The first lens unit LG11 includes a first lens L11. The second lens unit LG12 includes a second lens L12 and a first polarization state changing structure. The first polarization state changing structure is arranged between the second lens L12 and the beam splitter PBS1. In this example, the first polarization state changing structure is A first quarter-wave retarder (quarter-wave plate) QWP11 can be a half-wave plate or other structure for adjusting polarized light according to practical requirements. The third lens unit LG13 includes a third lens L13 and a second polarization state changing structure, the second polarization state changing structure is arranged between the third lens L13 and the beam splitter PBS1, the second polarization state changing structure in this example is A second quarter-wave retardation plate QWP12, which can be a half-wave plate or other structures for adjusting polarized light according to practical requirements, and a fourth lens L14. The fourth lens unit FLG1 includes a fifth lens L15. According to the first to fifth paragraphs of [implementation mode], where:

The third lens L13 is a cylindrical lens with negative refractive power, and the Y-axis direction of its cylindrical surface is a concave surface, and this concave surface is a spherical surface; the fourth lens L14 is a cylindrical lens with positive refractive power, and its side facing the beam splitter is a convex surface. The side facing the beam splitter is a cylindrical surface. The X-axis direction of the cylindrical surface is a plane and the Y-axis direction is a convex surface. The convex surface is a spherical surface. The cylindrical surface is coated or pasted with a high reflection film (not shown). When projecting, the light from an image source IS1 first enters and penetrates the first lens L11, and the light from the first lens L11 The surface S11 is incident on the beam splitter PBS1, and the beam splitter PBS1 then reflects the incident light. This embodiment takes the light with S polarized light as an example, and reflects it at the 45-degree inclined plane S15 to the second surface S12. The surface S12 exits the beam splitter PBS1 and enters the first quarter-wavelength retarder QWP11. After passing through the first quarter-wavelength retarder QWP11, the S-polarized light will be converted into circularly polarized light, and this circularly polarized light enters the second lens. L12 is reflected back to the second lens L12 by the high-reflection film (not shown) on the surface of the cylinder and enters the first quarter-wave retarder QWP11 again. When the circularly polarized light passes through the first quarter-wave retardation After the sheet QWP11, it will be converted into P polarized light. This P polarized light will enter the beam splitter PBS1 from the second surface S12 and will directly pass through the 45-degree inclined plane S15 and shoot to the third surface S13. The third surface S13 will exit the beam splitter PBS1 and enter the second surface. Two quarter-wave retarder QWP12, the above-mentioned P-polarized light will be converted into circularly polarized light after passing through the second quarter-wave retarder QWP12, and this circularly polarized light will enter the third lens L13 and the fourth lens L4 successively Afterwards, it is reflected by a high reflection film (not shown) on the surface of the cylinder, and then successively enters the fourth lens L14 and the third lens L13 and then enters the second quarter-wave retarder QWP12 again. After the quarter-wave retarder QWP12, it will be converted into S-polarized light. This S-polarized light is incident on the beam splitter PBS1 from the third surface S13, and is reflected at the 45-degree inclined plane S15 to the fourth surface S14. S14 exits the beam splitter PBS1 and then enters the fifth lens L15, and is finally projected on a projection plane PS1. The above-mentioned image source IS1 can be a self-luminous image panel or OLED, MicroLED, LCOS, LCD and the like. The setting of the cylindrical lens helps to adjust the single-axis light spot, and has the effect of shaping and extending the light path.

Utilizing the above-mentioned lens unit, aperture, beam splitter, first polarization state changing structure, second polarization state changing structure and the design satisfying at least one of the conditions (1) to (20), the imaging system 1 can effectively reduce the volume , effectively reduce weight, and effectively correct aberrations. Table 1 is a table of relevant parameters of each component of the imaging system 1 in FIG. 1 .

The concavity z of the aspheric surface of the aspheric lens in Table 1 is obtained by the following formula: z=ch ² /{1+[1-(k+1)c ² h ² ] ^1/2 }+Ah ⁴ +Bh ⁶ +Ch ⁸ +Dh ¹⁰ +Eh ¹² , where: c: curvature; h: vertical distance from any point on the lens surface to the optical axis; k: conic coefficient; A~E: aspheric coefficient. Table 2 is a list of relevant parameters of the aspheric surface of the aspheric lens in Table 1, where k is the conic constant, and A~E are the aspheric coefficients.

Table 3 shows the relevant parameter values of the imaging system 1 of the first embodiment and the calculated values corresponding to conditions (1) to (20). It can be seen from Table 3 that the imaging system 1 of the first embodiment can all satisfy the condition (1 ) to the requirements of condition (20).

In addition, the optical performance of the imaging system 1 of the first embodiment can also meet the requirements. It can be seen from FIG. 2A that the field curvature of the imaging system 1 of the first embodiment is between -0.8mm and 0.2mm. It can be seen from FIG. 2B that the distortion of the imaging system 1 of the first embodiment is between -25% and 0%. It can be seen from FIG. 2C that the MTF value of the imaging system 1 of the first embodiment is between 0.34 and 1.0. It is obvious that the field curvature and distortion of the imaging system 1 in the first embodiment can be effectively corrected, and the resolution of the lens can also meet the requirements, thereby obtaining better optical performance.

The second embodiment of the imaging system of the present invention will now be described in detail. Please refer to FIG. 3 , the imaging system 2 sequentially includes a diaphragm ST2, a fourth lens unit FLG2, a beam splitter PBS2 and a first lens unit LG21 along a first axis AX21 from a projection side to an image source side. , the imaging system 2 sequentially includes a second lens unit LG22 , a beam splitter PBS2 and a third lens unit LG23 along a second axis AX22 . The first lens unit LG21 includes a first lens L21. The second lens unit LG22 includes a second lens L22 and a first polarization state changing structure in sequence, and the first polarization state changing structure is arranged between the second lens L22 and the beam splitter PBS2, and this embodiment is a first four One-wave retarder QWP21, but not limited to this in practice. The third lens unit LG23 includes a third lens L23 and a second polarization state changing structure. The second polarization state changing structure is arranged between the third lens L23 and the beam splitter PBS2. This embodiment is a first polarization state changing structure. Two quarter-wave retarders QWP22, but practically not limited thereto. The fourth lens unit FLG2 includes a fifth lens L25. According to the first to fifth paragraphs of [implementation mode], where:

The third lens L23 has positive refractive power, and its cylindrical surface is convex in the Y-axis direction. The convex surface is a spherical surface, and the cylindrical surface is coated or pasted with a high reflection film (not shown). During projection, the light from an image source IS2 first enters and penetrates the first lens L21, and then enters the beam splitter PBS2 from the first surface S21. To repeat, the final projection is on a projection plane PS2. The above-mentioned image source IS2 can be a self-luminous image panel or OLED, MicroLED, LCOS, LCD.

Utilizing the above-mentioned lens unit, aperture, beam splitter, first polarization state changing structure, second polarization state changing structure and the design satisfying at least one of the conditions (1) to (20), the imaging system 2 can effectively reduce the volume , effectively reduce weight, and effectively correct aberrations. Table 4 is a table of relevant parameters of each component of the imaging system 2 in FIG. 3 .

The definition of the aspheric surface concave degree z of the aspheric lens in Table 4 is the same as that of the first The definition of the aspheric surface sag z of the aspheric lens in Table 1 in the embodiment is the same, and will not be repeated here. Table 5 is a list of relevant parameters of the aspheric surface of the aspheric lens in Table 1, where k is the conic constant, and A~E are the aspheric coefficients.

Table 6 shows the relevant parameter values of the imaging system 2 of the second embodiment and the calculated values corresponding to conditions (1) to (20). As can be seen from Table 6, the imaging system 2 of the second embodiment can all satisfy the condition (1 ) to the requirements of condition (20).

The structure of the third embodiment of the imaging system of the present invention is the same as that of the second embodiment. Only the length and height of the beam splitter PBS3 are different from the length and height of the beam splitter PBS2 in the corresponding component specifications, and the other corresponding component specifications are the same. .

Table 7 shows the relevant parameter values of the imaging system 3 (not shown) of the third embodiment and the calculated values corresponding to conditions (1) to (20). As can be seen from Table 7, the imaging system 3 of the third embodiment is all Can meet the requirements of condition (1) to condition (20).

In other embodiments, the settings of the beam splitter and the first lens unit, the second lens unit, and the third lens unit are not limited to the above, that is, if the light spot needs to be shaped into a circle in practice, the column in the first lens unit When the design of the surface lens and the cylindrical lens in the third lens unit has a numerical value in the radius of curvature in the X-axis direction, the cylindrical lens in the second lens unit is designed to have a numerical value in the radius of curvature in the Y-axis direction, for example When the projection side of the first lens is a plane, the image source side is a cylinder, the Y-axis direction of the cylinder is a plane, and the X-axis direction is a convex or concave surface, then the side of the third lens facing the beam splitter is a plane, and the non-facing The side of the beam splitter is cylindrical, the Y-axis direction of the cylindrical surface is also a plane, and the X-axis direction is also convex or concave, and the side of the second lens facing the beam splitter is a plane, and the side not facing the beam splitter is a cylindrical surface. The Y-axis direction is convex or concave, and the X-axis direction is a plane.

Please refer to Fig. 4, Fig. 4 is a schematic diagram of applying the imaging system of the present invention to AR, VR or XR. FLG3 exits the imaging system 3 to project an image, and the projected image enters the optical path turning element 40 again, and the optical path turning element 40 turns the projected image from the opposite direction The distance between the light source IS3 and the imaging system 3 of this case can be adjusted according to requirements, and each of the three imaging systems corresponds to a color light (red light, green light, blue light). The arrangement and quantity are not limited to the following The column shown in Figure 4 can be arranged into a rectangle according to actual needs. For example, if four imaging systems are set up, the upper two can be red light and green light, the lower two can be green light and blue light respectively, and the upper and lower two green light set on the diagonal.

In the above-mentioned embodiment, the cylindrical lenses in the first lens unit, the second lens unit and the third lens unit all have positive refractive power, but it can be understood that if the first lens unit, the second lens unit and the third lens unit All the cylindrical lenses are changed to have negative refractive power, which should also belong to the scope of the present invention. In the above embodiments, the first lens unit, the second lens unit, the third lens unit and the fourth lens unit may all include more than one lens, which also falls within the scope of the present invention.

The coordinates shown in the lower right corner of Figure 1 and Figure 3 are the coordinates of the mechanism, not the X, Y, and Z axes of the above-mentioned lens unit.

Although the present invention has been disclosed above in terms of implementation, it is not intended to limit the present invention. Any skilled person can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection of the present invention The scope shall be defined by the scope of the appended patent application.

1: Imaging system

LG11: The first lens unit

LG12: Second lens unit

LG13: Third lens unit

FLG1: Fourth lens unit

L11: first lens

L12: second lens

L13: third lens

L14: Fourth lens

L15: fifth lens

PBS1: Beamsplitter

ST1: Aperture

QWP11: The first polarization state changing structure (the first quarter-wave retarder)

QWP12: second polarization state change structure (second quarter-wave retarder)

PS1: projection surface

IS1: image source

AX11: first axis

AX12: second axis

S11: first surface

S12: second surface

S13: The third surface

S14: The fourth surface

S15: Bevel

YY: axis

ZZ: axis

Claims (9)

An imaging system, comprising: a beam splitter; a first lens unit, the first lens unit has a refractive power; a second lens unit, the second lens unit has a refractive power; a third lens unit, the third lens unit has Refractive power; and a fourth lens unit, the fourth lens unit has a positive refractive power; wherein the fourth lens unit, the beam splitter, and the first lens unit follow along a first axis from a projection side to an image source side sequence; wherein the second lens unit, the beam splitter and the third lens unit are arranged in sequence along a second axis; wherein the first axis intersects the second axis; wherein the imaging system satisfies at least one of the following Condition: 1<PBSL/PBSH

1.72; 0.5

PBSH/PBSL<1; 1.5

PBSL/PBST

2.3;1

PBSH/PBST

1.7; 1.9

OPL/PBSL

3;2.6

OPL/PBSH

4.2; 3.6

OPL/PBST

5.7; 0.01

BFL/OPL

0.04; 0.05

BFL/f

0.15; 0.25

IMGH/f

0.45; 0.1

IMGH/OPL

0.17; 1.4

3fy/f

2.3; 0.5

2fx/f

0.9; 0.9

1fy/f

1.7; 0.52

1fy/3fy

0.89; 0.3

2fx/3fy

0.5; 3fy>1fy; 1.7

f _FLG /f

3; 2fx≒1/((1/3fy)+(1/1fy)); 2fx=(3fy×1fy)/(3fy+1fy); among them, PBSL is one of the lengths of the imaging system, and PBSH is the length of the imaging system PBST is the thickness of the beam splitter, OPL is the optical path length of the imaging system, BFL is the distance from the image source side of the lens closest to the image source side to an image source along the first axis An interval, BFL is the distance from one image source side of the lens closest to the image source side to an image source along the first axis, f is an effective focal length of the imaging system, and IMGH is a half-image of the imaging system High, OPL is an optical path length of the imaging system, 1fy is the effective focal length in the Y-axis direction of the first lens unit, 2fx is the effective focal length in the X-axis direction of the second lens unit, and 3fy is the third lens unit An effective focal length in the Y-axis direction, f is an effective focal length of the imaging system, f _FLG is an effective focal length of the fourth lens unit, 1fy is an effective focal length in the Y-axis direction of the first lens unit, and 2fx is the effective focal length of the fourth lens unit One of the second lens units has an effective focal length in the X-axis direction, and 3fy is the effective focal length in the Y-axis direction of one of the third lens units. The imaging system described in item 1 of the scope of the patent application, wherein: the first lens unit includes a first lens; the second lens unit includes a second lens; the third lens unit includes a third lens; and the The fourth lens unit includes a fifth lens, and the fifth lens has positive refractive power; wherein the first lens, the second lens and the third lens are cylindrical lenses; wherein light from an image source passes through the first lens in sequence A lens unit, the beam splitter, the second lens unit, the beam splitter, the third lens unit, the beam splitter, and the fourth lens unit are finally projected on a projection surface. The imaging system described in item 2 of the scope of the patent application, wherein the second lens unit further includes a first polarization state changing structure, the first polarization state changing structure is arranged between the beam splitter and the second lens, the The third lens unit further includes a second polarization state changing structure disposed between the beam splitter and the third lens. The imaging system described in item 2 of the scope of the patent application, wherein the first lens, the second lens and the third lens have positive refractive power, and the second lens and the third lens further include a high reflective film coating or Attached to a cylindrical surface. The imaging system described in item 3 of the scope of the patent application, wherein the third lens unit further includes a fourth lens, the fourth lens has positive refractive power, and the third lens is interposed between the second polarization state changing structure and the first between the four lenses. The imaging system described in item 5 of the scope of the patent application, wherein the fourth lens is a cylindrical lens, and the second lens and the fourth lens further include a high reflective film coated or pasted on a cylindrical surface. The imaging system as described in any one of claims 1 to 6 of the patent application, wherein the first axis is perpendicular to the second axis. An imaging system, comprising: a beam splitter; a first lens unit, the first lens unit has a refractive power; a second lens unit, the second lens unit has a refractive power; a third lens unit, the third lens unit has Refractive power; and a fourth lens unit, the fourth lens unit has a positive refractive power; wherein the fourth lens unit, the beam splitter, and the first lens unit follow along a first axis from a projection side to an image source side sequence; wherein the second lens unit, the beam splitter and the third lens unit are arranged in sequence along a second axis; wherein the first axis intersects the second axis; wherein the third lens unit includes a first Three lenses, a fourth lens and a second polarization state changing structure, the second polarization state changing structure is arranged between the beam splitter and the third lens, the fourth lens has positive refractive power, and the third lens is between Between the second polarization state changing structure and the fourth lens. The imaging system described in item 8 of the patent application, wherein the imaging system satisfies at least one of the following conditions: 1<PBSL/PBSH

1.72; 0.5

PBSH/PBSL<1; 1.5

PBSL/PBST

2.3; 1

PBSH/PBST

1.7; 1.9

OPL/PBSL

3;2.6

OPL/PBSH

4.2; 3.6

OPL/PBST

5.7; 0.01

BFL/OPL

0.04; 0.05

BFL/f

0.15; 0.25

IMGH/f

0.45; 0.1

IMGH/OPL

0.17; 1.4

3fy/f

2.3; 0.5

2fx/f

0.9; 0.9

1fy/f

1.7; 0.52

1fy/3fy

0.89; 0.3

2fx/3fy

0.5; 3fy>1fy; 1.7

f _FLG /f

3; 2fx≒1/((1/3fy)+(1/1fy)); 2fx=(3fy×1fy)/(3fy+1fy); among them, PBSL is one of the lengths of the imaging system, and PBSH is the length of the imaging system A height, PBST is a thickness of the beam splitter, OPL is an optical path length of the imaging system, BFL is the distance from the image source side of the lens closest to the image source side to an image source along the first axis An interval, BFL is the distance from one image source side of the lens closest to the image source side to an image source along the first axis, f is an effective focal length of the imaging system, and IMGH is a half-image of the imaging system High, OPL is an optical path length of the imaging system, 1fy is the effective focal length in the Y-axis direction of the first lens unit, 2fx is the effective focal length in the X-axis direction of the second lens unit, and 3fy is the third lens unit an effective focal length in the Y-axis direction, f is an effective focal length of the imaging system, and f _FLG is an effective focal length of the fourth lens unit.

Images