TWI633340B - Ocular optical system - Google Patents

Abstract

An eyepiece optical system for imaging imaging light from a display screen through an eyepiece optical system into an observer's eye. The direction toward the eye is the side of the eye, and the direction toward the display screen is the display side. The eyepiece optical system includes a lens having a mesh side and a display side. The lens has an optical axis extending from the display side to the side of the eye. The display side of the lens is designed with a Fresnel lens, and the display side has a plurality of effective sub-surfaces and a plurality of invalid sub-surfaces for imaging the imaging light, and each invalid sub-surface is connected to the adjacent two effective sub-surfaces. surface. The eyepiece optical system conforms to: 1.500 ≦ R1/SagI ≦ 4.000, where SagI is the sum of the lengths of the plurality of vertical projections of the effective sub-surfaces on the optical axis, respectively, and R1 is the optical effective radius of the display side.

Description

Eyepiece optical system

This invention relates to an optical system and, more particularly, to an eyepiece optical system.

Virtual reality (VR) is a virtual world that uses computer technology to simulate a three-dimensional space, providing users with sensory simulations such as vision and hearing, so that users can feel the immersion. Currently, existing VR devices are mainly based on visual experience. The stereoscopic vision is achieved by simulating the parallax of the human eye by dividing the picture with slightly different views of the left and right eyes. In order to reduce the size of the virtual reality device and allow the user to obtain a magnified visual experience through a small display screen, the eyepiece optical system with magnification function has become one of the themes of the development of VR research.

In the eyepiece optical system, in order to pursue thinness and thinness, the design of a Fresnel lens can be utilized as a means to improve the problem that the optical lens system is too long and heavy. However, the surface of the Fresnel lens has a plurality of concentric annular teeth, each annular tooth having an effective sub-surface capable of refracting incident light to a predetermined direction and an invalid sub-surface connecting adjacent two effective sub-surfaces, and the invalid sub-surface and The intersection of the effective sub-surfaces and the ineffective sub-surfaces are prone to stray light, which affects the imaging quality. Therefore, in addition to designing In addition to the thin eyepiece optical lens, it is also an urgent task to have good image quality.

The present invention provides an eyepiece optical system that combines the characteristics of light and thin and low stray light.

An embodiment of the present invention provides an eyepiece optical system for imaging imaging light from a display screen through an eyepiece optical system into an observer's eye. The direction toward the eye is the side of the eye, and the direction toward the display screen is the display side. The eyepiece optical system includes a lens having a first side facing the side of the eye and passing the imaging light and a display side facing the display side and passing the imaging light. The lens has an optical axis extending from the display side to the side of the eye. The display side of the lens is designed with a Fresnel lens, and the display side has a plurality of effective sub-surfaces and a plurality of invalid sub-surfaces for imaging the imaging light, and each invalid sub-surface is connected to the adjacent two effective sub-surfaces. surface. The eyepiece optical system conforms to: 1.500 ≦ R1/SagI ≦ 4.000, where SagI is the sum of the lengths of the multiple vertical projections of the effective sub-surfaces on the optical axis, and R1 is the optical effective radius of the display side (half of clear aperture) ).

Based on the above, since the eyepiece optical system of the embodiment of the present invention conforms to 1.500 ≦R1/SagI ≦4.000, the area of the invalid sub-surface can be well controlled to reduce the stray light of the eyepiece optical system, thereby making the eyepiece optical system good. Imaging quality.

In order to make the above features and advantages of the present invention more apparent, the following is a special The embodiments are described in detail below in conjunction with the drawings.

10, V100‧‧‧ eyepiece optical system

100, V50‧‧‧ display screen

2‧‧‧瞳孔

3‧‧‧ lens

31‧‧‧ eyes

311, 313, 321, 323‧‧ ‧ convex face

32‧‧‧Show side

A‧‧‧Axis near the optical axis

B1, B1'‧‧‧ basal plane

B2‧‧‧ reference plane

C‧‧‧near the circle

D1‧‧‧ out diameter

D2‧‧‧ shows the diameter of the circle

D3‧‧‧length of vertical projection

E‧‧‧Extension

I‧‧‧ optical axis

Lc‧‧‧ chief ray

Lm‧‧‧ edge light

M, R‧‧ points

P1‧‧‧ effective sub-surface

P2‧‧‧ Invalid sub-surface

Q1‧‧‧ starting point

Vertex of Q2‧‧‧

V60‧‧ eyes

VD‧‧‧ virtual image distance

VI‧‧‧ imaging light

VV‧‧·Enlarge the virtual image

‧‧‧‧Maximum tilt angle

ω‧‧‧Half-eye view

Figure 1 is a schematic view showing an eyepiece optical system.

Fig. 2 is a schematic view showing the surface structure of a lens.

Figure 3 is a schematic view showing the surface relief structure of a lens and the focus of light.

Fig. 4 is a schematic view showing the surface structure of a lens of an example one.

Fig. 5 is a schematic view showing the surface structure of a lens of an example two.

Fig. 6 is a schematic view showing the surface structure of a lens of an example three.

Figure 7 is a schematic illustration of an eyepiece optical system in accordance with a first embodiment of the present invention.

8A to 8D are longitudinal spherical aberration and various aberration diagrams of the eyepiece optical system of the first embodiment.

Fig. 9 shows detailed optical data of the eyepiece optical system of the first embodiment of the present invention.

Figure 10 shows the aspherical parameters of the eyepiece optical system of the first embodiment of the present invention.

Figure 11 is a schematic view of an eyepiece optical system of a second embodiment of the present invention.

12A to 12D are longitudinal spherical aberration and various aberration diagrams of the eyepiece optical system of the second embodiment.

Figure 13 shows detailed optical data of the eyepiece optical system of the second embodiment of the present invention.

Figure 14 shows the aspherical parameters of the eyepiece optical system of the second embodiment of the present invention.

Figure 15 is a schematic view of an eyepiece optical system of a third embodiment of the present invention.

16A to 16D are longitudinal spherical aberration and various aberration diagrams of the eyepiece optical system of the third embodiment.

Figure 17 shows detailed optical data of the eyepiece optical system of the third embodiment of the present invention.

Figure 18 shows the aspherical parameters of the eyepiece optical system of the third embodiment of the present invention.

Figure 19 is a schematic view of an eyepiece optical system of a fourth embodiment of the present invention.

20A to 20D are longitudinal spherical aberration and various aberration diagrams of the eyepiece optical system of the fourth embodiment.

Figure 21 shows detailed optical data of the eyepiece optical system of the fourth embodiment of the present invention.

Figure 22 shows the aspherical parameters of the eyepiece optical system of the fourth embodiment of the present invention.

Figure 23 is a schematic view of an eyepiece optical system of a fifth embodiment of the present invention.

24A to 24D are longitudinal spherical aberration and various aberration diagrams of the eyepiece optical system of the fifth embodiment.

Fig. 25 shows detailed optical data of the eyepiece optical system of the fifth embodiment of the present invention.

Figure 26 is a view showing aspherical parameters of an eyepiece optical system of a fifth embodiment of the present invention.

Figure 27 is a schematic illustration of the lens of Figure 7.

28 is a schematic view of the lens of FIG.

Fig. 29 shows numerical values of respective important parameters of the eyepiece optical system of the first to fifth embodiments of the present invention and their relational expressions.

In general, the direction of the light of the eyepiece optical system V100 is that an imaging ray VI is emitted from the display image V50, enters the eye V60 via the eyepiece optical system V100, focuses on the retina of the eye V60, and produces an enlarged virtual image VV at the virtual image distance VD, such as Figure 1 shows. The criterion for judging the optical specifications of the present invention is to assume that the ray direction is reversely tracked as a parallel imaging ray from the eye side through the eyepiece optical system to the display image.

As used in this specification, "a lens having a positive refractive power (or a negative refractive power)" means that the refractive index of the lens on the optical axis calculated by Gaussian optical theory is positive (or negative). The side of the eye and the side of the display are defined as the range through which the imaging light passes, wherein the imaging light includes a chief ray Lc and a marginal ray Lm, as shown in FIG. 2, where I is the optical axis and the lens is The optical axis I is symmetric with respect to each other in a radial direction. The region of the light passing through the optical axis is the region A near the optical axis, the region through which the edge light passes is the region C near the circumference, and the lens further includes an extension E ( That is, the radially outward region of the region C near the circumference, for the lens to be assembled in an optical imaging lens, the ideal imaging light does not pass through the extension portion E, but the structure and shape of the extension portion E are not In this regard, the following embodiments omits portions of the extensions for simplicity of the drawing. In more detail, the method of determining the area near the surface or the optical axis, the area near the circumference, or the range of the plurality of areas is as follows:

1. Please refer to FIG. 2, which is a cross-sectional view of a lens in the radial direction. In the cross-sectional view, when determining the range of the foregoing region, a center point is defined as an intersection with the optical axis on the surface of the lens, and a transition point is a point on the surface of the lens, and The line passing through this point is perpendicular to the optical axis. If there are a plurality of transition points outward in the radial direction, the first transition point and the second transition point are sequentially, and the transition point farthest from the optical axis in the effective half-effect path is the Nth transition point. The range between the center point and the first transition point is a region near the optical axis, and the radially outward region of the Nth transition point is a region near the circumference, and different regions can be distinguished according to the respective transition points. Further, the effective radius is the vertical distance at which the edge ray Lm intersects the lens surface to the optical axis I.

2. As shown in Fig. 3, the shape concavities and convexities of the region are determined by the intersection of the light rays (or the light ray extending lines) passing through the region and the optical axis on the eye side or the display side (the light focus determination mode). For example, when light passes through the area, the light will be focused toward the display side, and the focus of the optical axis will be on the display side, such as point R in Figure 3, where the area is a convex surface. Conversely, if the light passes through the certain area, the light will diverge, and the extension line and the focus of the optical axis are on the side of the eye. For example, at point M in Fig. 3, the area is a concave surface, so the center point is between the first transition point. The convex portion, the radially outward portion of the first switching point is a concave surface; as can be seen from FIG. 3, the switching point is a boundary point of the convex surface of the convex surface, so that the inner side of the region adjacent to the radial direction can be defined. The area has a different face shape with the transition point as a boundary. In addition, if the shape of the region near the optical axis is judged according to the judgment of the person in the field, the R value (referring to the radius of curvature of the paraxial axis, generally refers to the R on the lens data in the optical software). Value) Positive and negative judgment bump. In terms of the side, when the R value is positive, it is determined as a convex surface, and when the R value is negative, it is determined as a concave surface; when the R side is positive, when the R value is positive, it is determined as a concave surface, when R is When the value is negative, it is determined as a convex surface, and the unevenness determined by this method is the same as the light focus determination method.

3. If there is no transition point on the surface of the lens, the area near the optical axis is defined as 0~50% of the effective radius, and the area near the circumference is defined as 50~100% of the effective radius.

The lens display side surface of the first example of FIG. 4 has only the first transition point on the effective radius, and the first region is the vicinity of the optical axis, and the second region is the region near the circumference. This lens shows that the R value of the side is positive, so that the area near the optical axis has a concave surface; the surface shape of the area near the circumference is different from the inner area of the area immediately adjacent to the area. That is, the area near the circumference and the area near the optical axis are different; the area near the circumference has a convex surface.

The lens side surface of the second example of Fig. 5 has first and second transition points on the effective radius, the first region is the vicinity of the optical axis, and the third region is the region near the circumference. The R value of the side of the lens is positive, so that the area near the optical axis is determined to be a convex surface; the area between the first switching point and the second switching point (second area) has a concave surface, and the area near the circumference (third area) Has a convex face.

In the example 3 of the lens, the surface of the lens has no transition point on the effective radius. At this time, the effective radius is 0%~50%, and the area near the optical axis is 50%~100%. Since the R value in the vicinity of the optical axis is positive, the side of the eye has a convex portion in the vicinity of the optical axis; and there is no transition point between the region near the circumference and the region near the optical axis, so that the region near the circumference has a convex portion.

Fig. 7 is a schematic view of an eyepiece optical system according to a first embodiment of the present invention, and Figs. 8A to 8D are longitudinal spherical aberration and various aberration diagrams of the eyepiece optical system of the first embodiment. Referring first to FIG. 7, the eyepiece optical system 10 of the first embodiment of the present invention is for causing imaging light of the display screen 100 to pass through the eyepiece optical system 10 and the observer. The pupil 2 of the eye is imaged into the observer's eye, and the display may be a vertical optical axis or an angle not equal to 90 degrees with the optical axis. The eye side is one side toward the direction of the observer's eyes, and the display side is one side facing the direction of the display screen 100. In the present embodiment, the eyepiece optical system 10 includes a lens 3 having an optical axis I extending from the display side toward the side of the eye. When the imaging light of the display screen 100 is emitted, it passes through the lens 3 and then enters the observer's eye via the pupil 2 of the viewer. The imaging ray then forms an image of the retina of the observer's eye. Specifically, the lens 3 of the eyepiece optical system 10 includes a mesh side 31 that faces the mesh side and allows imaging light to pass therethrough, and a display side 32 that faces the display side and allows imaging light to pass therethrough.

In addition, in order to meet the demand for light weight of the product, the lens 3 has a refractive index and is made of a plastic material, but the material of the lens 3 is not limited thereto.

The lens 3 has a positive refractive power. The eye side 31 of the lens 3 is a convex surface, and has a convex portion 311 located in the vicinity of the optical axis I and a convex portion 313 located in the vicinity of the circumference. The display side 32 of the lens 3 is designed with a Fresnel lens, which in the present embodiment is shown as a Fresnel surface, the surface of the Fresnel lens. 27 is a schematic view of the lens of FIG. 7. In order to clearly show the effective sub-surface and the ineffective sub-surface of the display side of the lens, the dimensions of the effective sub-surface and the invalid sub-surface are exaggeratedly enlarged, and the effective sub-surface and the null sub-object The number of faces is reduced. Referring to FIG. 7 and FIG. 27, the side surface 32 has a plurality of effective sub-surfaces P1 and a plurality of invalid sub-surfaces P2. The effective sub-surfaces P1 are used to image the imaging light, and each of the invalid sub-surfaces P2 is connected to the adjacent two. Sub-surface P1. Except that the effective sub-surface P1 on the optical axis I is circular, the remaining effective sub-surface P1 and the null sub-surface P2 are alternately arranged in the radial direction. Arranged concentric rings. These effective sub-surfaces P1 form Fresnel surfaces with these ineffective sub-surfaces P2. The display side 32 of the lens 3 has a convex portion 321 located in the vicinity of the optical axis I and a convex portion 323 located in the vicinity of the circumference. In this embodiment, the display side surface 32 is a planar Fresnel surface, and each effective sub-surface P1 extends from a base surface B1 to the display side, wherein the base surface B1 is perpendicular to the optical axis I. flat.

Other detailed optical data of the first embodiment is shown in FIG. The overall system focal length (EFL) of the eyepiece optical system 10 of the first embodiment is 34.896 millimeters (millimeter, mm), and the half apparent field of view (ω) is 47.533°, and the aperture value (f) -number, Fno) is 8.724. Specifically, the "aperture value" in the present specification is an aperture value calculated by considering the pupil of the observer as an entrance pupil according to the principle of reversibility of light. In addition, the maximum image angle of the single eye of the observer of the eyepiece optical system 10 of the first embodiment corresponds to an image circle diameter (ICD) of the display screen 100 of 54.500 mm, wherein the image circle is the observer. The maximum display screen range visible by the eye through the eyepiece optical system, and the system length (SL) of the eyepiece optical system 10 of the first embodiment is 47.944 mm, wherein the system length is the observer's pupil 2 to the display screen 100 in the light. The distance on axis I. In addition, the effective radius in FIG. 9 means half of the optical effective aperture.

In the present embodiment, the eye side 31 of the lens 3 is an aspherical surface, and the display side 32 of the lens 3 is a Fresnel surface, wherein the effective sub-surface P1 of each tooth of the Fresnel surface is aspherical, and the following side is shown The aspherical coefficient of 32 is used to represent the effective sub-surface P1 of these teeth, and these aspheric surfaces are defined by the following formula:

Where: Y: the vertical distance of the point on the aspherical curve from the optical axis I; Z: the depth of the aspherical surface (the point on the aspheric surface from which the optical axis I is Y, and the tangent to the vertex on the aspherical optical axis I) , the vertical distance between the two); R: the radius of curvature at the near-optical axis I of the lens surface; K: the conic constant; a _{2 i} : the 2i-th order aspheric coefficient.

The aspherical coefficients of the eye side 31 and the display side 32 of the lens 3 in the formula (1) are as shown in FIG. Here, the column number 31 in FIG. 10 indicates that it is the aspherical coefficient of the eye side 31 of the lens 3, and the other fields are similar.

Further, the relationship between the important parameters in the eyepiece optical system 10 of the first embodiment is as shown in FIG.

Wherein, the EFL is the system focal length of the eyepiece optical system 10, that is, the effective focal length of the eyepiece optical system 10; ω is the half-eye viewing angle of the eyepiece optical system 10, that is, the observer's half field of view angle, as depicted in FIG. T1 is the thickness of the lens 3 on the optical axis I; GD is the display side 32 of the lens 3 to the display screen 100 in the light The distance on the axis I, that is, the air gap of the lens 3 to the display screen 100 on the optical axis I; TTL is the distance from the eye side 31 of the lens 3 to the display screen 100 on the optical axis I; ER is the exit distance (Eye relief) ) is the distance from the pupil 2 of the observer to the eye side 31 of the lens 3 on the optical axis I; SL is the length of the system, the distance from the pupil 2 of the observer to the optical axis I of the display screen 100; EPD is the eyepiece optics The diameter of the pupil pupil diameter D1 of the system 10 is shown as the diameter of the pupil 2 corresponding to the observer, as shown in FIG. 1; the ICD is the maximum angle of view of the single eye of the observer. The display screen 100 displays the circle diameter D2 (as shown in FIG. 1); VD is the virtual image distance, that is, the distance between the enlarged virtual image VV and the observer's pupil 2 (ie, the exit pupil), as shown in FIG. The virtual image distance VD; α is the maximum tilt angle of these effective sub-surfaces P1 of the lens 3 with respect to a reference plane B2 perpendicular to the optical axis I, as shown in FIGS. 27 and 28. In an embodiment of the invention, this maximum tilt angle is the tilt angle at the outermost periphery of the effective sub-surface P1 farthest from the optical axis I; R1 is the optical effective radius of the display side 32 of the lens 3 (half Of clear aperture); SagI is the sum of the lengths D3 of the plurality of vertical projections of the effective sub-surfaces P1 of the lens 3 on the optical axis I, as shown in FIGS. 27 and 28. Wherein, each effective sub-surface P1 has a starting point Q1 closest to the head side and a vertex Q2 closest to the display side, and the length D3 of each vertical projection is the starting point Q1 of the corresponding effective sub-surface P1 to The vertex Q2 is vertically projected on the optical axis I.

Further, it is further defined that n1 is the refractive index of the lens 3; V1 is the Abbe number of the lens 3.

In the first embodiment, R1/SagI = 2.196.

8A to 8D, FIG. 8A to FIG. 8D are diagrams showing aberrations of the eyepiece optical system of the first embodiment, and the reverse tracking of the light direction is a parallel imaging light passing through the pupil 2 from the mesh side. And various aberration diagrams obtained by focusing the eyepiece optical system 10 to the display screen 100. In the present embodiment, the aberration performances presented in the various aberration diagrams described above determine the aberration performance of the imaging light from the display screen 100 in the retinal imaging of the observer's eyes. That is to say, when the aberrations presented in the above aberration diagrams are small, the aberrations of the imaging of the retina of the observer's eyes are also small, so that the observer can see the image quality. Good image.

Specifically, the diagram of FIG. 8A illustrates the longitudinal spherical aberration of the first embodiment. (Longitudinal spherical aberration), the patterns of FIG. 8B and FIG. 8C respectively illustrate the field curvature aberration in the sagittal direction and the field curvature aberration in the tangential direction of the first embodiment, The 8D pattern illustrates the distortion aberration of the first embodiment. The longitudinal spherical aberration diagram of the first embodiment is shown in Fig. 8A when the pupil radius is 2.000 mm (i.e., when the exit pupil diameter EPD of the eyepiece optical system 10 is 4.000 mm). In addition, in the vertical spherical aberration diagram of the first embodiment, in FIG. 8A, the curves formed by each of the wavelengths are close to each other and are close to the middle, indicating that the off-axis rays of different wavelengths are concentrated near the imaging point, The deflection amplitude of the curve of each wavelength can be seen that the deviation of the imaging point of the off-axis light of different heights is controlled within the range of ±0.55 mm, so this embodiment does significantly improve the spherical aberration of the same wavelength, in addition, 466 nm The distances of the three representative wavelengths of 542 nm and 643 nm are also quite close to each other, and the imaging positions representing the light of different wavelengths have been quite concentrated, so that the chromatic aberration is also significantly improved.

In the two field curvature aberration diagrams of FIGS. 8B and 8C, the focal length variation of the three representative wavelengths over the entire field of view falls within the range of ±1.45 mm, which illustrates the eyepiece optical system 10 of the first embodiment. Can effectively eliminate aberrations. The distortion aberration diagram of FIG. 8D shows that the distortion aberration of the first embodiment is maintained within a range of ±28%, indicating that the distortion aberration of the first embodiment has met the imaging quality requirements of the optical system. It is to be noted that the first embodiment can provide better image quality under the condition that the length of the system has been shortened to about 47.944 mm compared with the existing eyepiece optical system, so that the first embodiment can maintain good optical performance. The eyepiece optical system is shortened to achieve a thinner product design. Further, the eyepiece optics of the first embodiment System 10 has a large viewing angle and is capable of correcting aberrations while maintaining good image quality. Further, in the first embodiment, since the area of 1.500 ≦ R1/SagI ≦ 4.000 is satisfied, the area of the invalid sub-surface P2 can be well controlled, thereby reducing the generation of stray light.

Figure 11 is a schematic view of an eyepiece optical system according to a second embodiment of the present invention, and Figures 12A to 12D are longitudinal spherical aberration and various aberration diagrams of the eyepiece optical system of the second embodiment. Referring first to FIG. 11, a second embodiment of the eyepiece optical system 10 of the present invention is substantially similar to the first embodiment, and only the optical data, the aspherical coefficients, and the parameters of the lens 3 are more or less different, and The display side 32 of the lens 3 of the eyepiece optical system 10 of the second embodiment is a curved Fresnel surface. 28 is a schematic view of the lens of FIG. 11. In order to clearly show the effective sub-surface and the ineffective sub-surface of the display side of the lens, the dimensions of the effective sub-surface and the invalid sub-surface are exaggeratedly enlarged, and the effective sub-surface and the null sub-object The number of faces is reduced. Referring to FIG. 11 and FIG. 28, in the embodiment, the display side surface 32 is a curved Fresnel surface, and each effective sub-surface P1 extends from a base surface B1' to the display side, wherein the base surface B1' is a curved surface. In other words, the starting points Q1 of these effective sub-surfaces P1 all fall on the basal plane B1' in the form of a curved surface. The base surface of the extended Fresnel surface may be a spherical or aspherical surface similar to a general lens, which may be rotationally symmetric with respect to the optical axis I as an axis of symmetry. In the present embodiment, the base surface B1' is aspherical.

In the present embodiment, the effective sub-surfaces P1 of the display side 32 can conform to the aspherical formula (1) described above. Further, the base surface B1' of the display side surface 32 can also conform to the aspherical formula (1) described above, but the definition of the parameter R in the formula (1) is changed to the base surface B1'. The radius of curvature at the near optical axis I. Further, as shown in FIG. 14, the aspherical coefficients of the eye side 31 and the display side surface 32 of the lens 3 of the second embodiment in the formula (1), wherein "the effective sub-surface of 32" are in the two columns The parameters belong to the parameters of the effective sub-surfaces P1 of the display side 32, and the parameters of the two columns of the "base surface of 32" belong to the parameters of the base surface B1' of the display side 32, wherein the field of curvature radius of the lowermost right side of FIG. "-245.748" means that the R value of the base surface B1' in the formula (1) is -245.748 mm.

The detailed optical data of the eyepiece optical system 10 of the second embodiment is as shown in Fig. 13, and the overall system focal length of the eyepiece optical system 10 of the second embodiment is 46.740 mm, and the half-eye viewing angle (ω) is 47.371 °, and the aperture value ( Fno) is 11.685, the ICD is 71.000 mm, and the system length (SL) is 66.898 mm.

Further, the relationship between the important parameters in the eyepiece optical system 10 of the second embodiment is as shown in Fig. 29, and R1/SagI = 2.472 of the present embodiment is superior to the first embodiment.

The longitudinal spherical aberration diagram of the second embodiment is shown in Fig. 12A when the pupil radius is 2.000 mm (i.e., when the exit pupil diameter EPD of the eyepiece optical system 10 is 4.000 mm). The longitudinal spherical aberration of the second embodiment is shown in Fig. 12A, and the imaging point deviation of off-axis rays of different heights is controlled within a range of ±0.83 mm. In the two field curvature aberration diagrams of Figs. 12B and 12C, the amount of change in the focal length of the three representative wavelengths over the entire field of view falls within the range of ± 0.9 mm. On the other hand, the distortion aberration diagram of Fig. 12D shows that the distortion aberration of the second embodiment is maintained within the range of ±30%. Accordingly, the second embodiment can provide better image quality even when the system length has been shortened to about 46.740 mm as compared with the existing eyepiece optical system.

As can be seen from the above description, the second embodiment is compared to the first embodiment. The advantage is that the field curvature of the second embodiment is smaller than that of the first embodiment, and the second embodiment can more effectively reduce the influence of stray light.

Figure 15 is a schematic view of an eyepiece optical system according to a third embodiment of the present invention, and Figures 16A to 16D are longitudinal spherical aberration and various aberration diagrams of the eyepiece optical system of the third embodiment. Referring first to Figure 15, a third embodiment of the eyepiece optical system 10 of the present invention is substantially similar to the first embodiment, with only optical data, aspheric coefficients, and parameters of the lens 3 being somewhat different. The difference from the first embodiment is that the eye side 31 of the lens 3 of the third embodiment is a spherical surface. As in the first embodiment, the display side 32 of the lens 3 of the third embodiment is a planar Fresnel surface whose base surface B1 is a plane perpendicular to the optical axis I.

The detailed optical data of the eyepiece optical system 10 of the third embodiment is as shown in Fig. 17, and the overall system focal length of the eyepiece optical system 10 of the third embodiment is 32.681 mm, and the half-eye viewing angle (ω) is 44.833 °, and the aperture value ( Fno) is 9.078, ICD is 48.000 mm, and system length (SL) is 45.240 mm.

As shown in Fig. 18, the aspherical coefficients of the display side 32 of the lens 3 of the third embodiment are in the formula (1).

Further, the relationship between the important parameters in the eyepiece optical system 10 of the third embodiment is as shown in Fig. 29, and R1/SagI = 2.985 in the present embodiment is superior to the first embodiment.

The longitudinal spherical aberration diagram of the third embodiment is shown in Fig. 16A when the pupil radius is 1.800 mm (i.e., when the exit pupil diameter EPD of the eyepiece optical system 10 is 3.600 mm). The longitudinal spherical aberration of the third embodiment is shown in Fig. 16A, and the imaging point deviation of off-axis rays of different heights is controlled within a range of ± 0.43 mm. In Figure 16B In the two field curvature aberration diagrams of Fig. 16C, the amount of change in the focal length of the three representative wavelengths over the entire field of view falls within the range of ±1.1 mm. On the other hand, the distortion aberration diagram of Fig. 16D shows that the distortion aberration of the third embodiment is maintained within the range of ±25%. Accordingly, the third embodiment can provide better image quality even when the system length has been shortened to about 45.240 mm as compared with the existing eyepiece optical system.

As can be seen from the above description, the third embodiment has an advantage over the first embodiment in that the system length of the third embodiment is smaller than the system length of the first embodiment, and the longitudinal spherical aberration of the third embodiment is smaller than the first embodiment. The longitudinal spherical aberration of the example, the field curvature of the third embodiment is smaller than that of the first embodiment, and the distortion of the third embodiment is smaller than that of the first embodiment, and the third embodiment can more effectively reduce the influence of stray light. .

Figure 19 is a schematic view of an eyepiece optical system according to a fourth embodiment of the present invention, and Figures 20A to 20D are longitudinal spherical aberration and various aberration diagrams of the eyepiece optical system of the fourth embodiment. Referring first to Figure 19, a fourth embodiment of the eyepiece optical system 10 of the present invention is substantially similar to the first embodiment in that only the optical data, the aspherical coefficients, and the parameters of the lens 3 are somewhat different. As in the first embodiment, the display side 32 of the lens 3 of the fourth embodiment is a planar Fresnel surface whose base surface B1 is a plane perpendicular to the optical axis I.

The detailed optical data of the eyepiece optical system 10 is as shown in Fig. 21, and the overall system focal length of the eyepiece optical system 10 of the fourth embodiment is 36.986 mm, the half-eye viewing angle (ω) is 49.934°, and the aperture value (Fno) is 9.246. The ICD is 56.400 mm and the system length (SL) is 52.542 mm.

As shown in FIG. 22, the object side 31 of the lens 3 of the fourth embodiment is The aspheric coefficients of the side faces 32 in the formula (1) are shown.

Further, the relationship between the important parameters in the eyepiece optical system 10 of the fourth embodiment is as shown in Fig. 29, and R1/SagI = 2.322 of the present embodiment is superior to the first embodiment.

The longitudinal spherical aberration diagram of the fourth embodiment is shown in Fig. 20A when the pupil radius is 2.000 mm (i.e., when the exit pupil diameter EPD of the eyepiece optical system 10 is 4.000 mm). The longitudinal spherical aberration of the fourth embodiment is shown in Fig. 20A, and the imaging point deviation of the off-axis rays of different heights is controlled within the range of ±0.59 mm. In the two field curvature aberration diagrams of Figs. 20B and 20C, the amount of change in the focal length of the three representative wavelengths over the entire field of view falls within the range of ±1 mm. On the other hand, the distortion aberration diagram of Fig. 20D shows that the distortion aberration of the fourth embodiment is maintained within the range of ± 35%. Accordingly, the fourth embodiment can provide better image quality even when the system length has been shortened to about 52.542 mm as compared with the existing eyepiece optical system.

As can be seen from the above description, the fourth embodiment has an advantage over the first embodiment in that the half-eye viewing angle of the fourth embodiment is larger than the half-eye viewing angle of the first embodiment, and the field curvature of the fourth embodiment is smaller than the first embodiment. The field curvature of an embodiment, and the fourth embodiment can more effectively reduce stray light effects.

Figure 23 is a schematic view of an eyepiece optical system according to a fifth embodiment of the present invention, and Figures 24A to 24D are longitudinal spherical aberration and various aberration diagrams of the eyepiece optical system of the fifth embodiment. Referring first to Figure 23, a fifth embodiment of the eyepiece optical system 10 of the present invention is substantially similar to the first embodiment, with only optical data, aspheric coefficients, and parameters of the lens 3 being somewhat different. In the present embodiment, the display side 32 of the lens 3 is a curved Fresnel surface, and the base surface B1' is a curved surface, for example, an aspherical surface.

The detailed optical data of the eyepiece optical system 10 of the fifth embodiment is as shown in Fig. 25, and the overall system focal length of the eyepiece optical system 10 of the fifth embodiment is 35.271 mm, and the half-eye viewing angle (ω) is 47.566 °, and the aperture value ( Fno) is 8.818, the ICD is 56.000 mm, and the system length (SL) is 54.934 mm.

As shown in Fig. 26, the aspherical coefficients of the base surface 31 of the first lens 3 of the fifth embodiment and the base surface B1' and the effective sub-surface P1 of the display side surface 32 in the formula (1) are shown.

Further, the relationship between the important parameters in the eyepiece optical system 10 of the fifth embodiment is as shown in Fig. 29, and R1/SagI = 1.771 of this embodiment.

The longitudinal spherical aberration diagram of the fifth embodiment is shown in Fig. 24A when the pupil radius is 2.000 mm (i.e., when the exit pupil diameter EPD of the eyepiece optical system 10 is 4.000 mm). The longitudinal spherical aberration diagram of the fifth embodiment is shown in Fig. 24A, and the imaging point deviation of off-axis rays of different heights is controlled within a range of ±0.54 mm. In the two field curvature aberration diagrams of Figs. 24B and 24C, the amount of change in the focal length of the three representative wavelengths over the entire field of view falls within the range of ±1.6 mm. On the other hand, the distortion aberration diagram of Fig. 24D shows that the distortion aberration of the fifth embodiment is maintained within the range of ± 28%. Accordingly, the fifth embodiment can provide better image quality even when the system length has been shortened to about 54.934 mm as compared with the existing eyepiece optical system.

As apparent from the above description, the fifth embodiment has an advantage over the first embodiment in that the half-eye angle of view of the fifth embodiment is larger than the half-eye angle of view of the first embodiment.

See Figure 29 again. Figure 29 is a view showing the first to fifth embodiments described above A table of various optical parameters, in which the parameters of the columns "T1" to "SL" are in millimeters (mm), and the unit of "α" is degrees.

When the relationship between the optical parameters in the eyepiece optical system 10 of the embodiment of the present invention conforms to the following conditional formula or at least one of the following designs, the designer can be designed to have good optical performance and the overall length is effectively shortened. And technically feasible eyepiece optical system:

1. By designing one side of the lens 3 as a Fresnel surface (including a flat Fresnel surface or a curved Fresnel surface), it helps to thin the lens, thereby shortening the overall system length and achieving lightweight effect.

2. The Fresnel surface (for example, the display side 32 of the lens 3) conforms to 1.500 ≦R1/SagI ≦4.000, which can effectively reduce the generation of stray light, and the effect is better when it meets 1.700 ≦R1/SagI ≦ 3.200.

Third, the eyepiece optical system conforms to 1.360≦ICD/EFL≦1.630 to effectively maintain imaging quality under a large half-eye view.

4. The Fresnel surface (for example, the display side 32 of the lens 3) conforms to 25.000°≦α≦52.000°, which makes the effective sub-surface P1 of the Fresnel surface smoother, and also helps to reduce the generation of stray light. And when the above Fresnel surface meets 29.000 ° ≦ α ≦ 48.500 °, the effect is better.

5. When the Fresnel surface is a planar Fresnel surface (i.e., its base surface B1 is a flat surface), the overall eyepiece optical system 10 can be made lighter and thinner.

In view of the unpredictability of the optical system design, under the framework of the present invention, the above conditional expression can preferably make the eyepiece optical system 10 of the present invention shorter. The system length, larger viewing angle, better imaging quality, or better assembly yield improves the shortcomings of the prior art.

In addition, with regard to the exemplary defined relationship listed above, the unequal amount may be arbitrarily combined and applied in the embodiment of the present invention, and is not limited thereto. In the implementation of the present invention, in addition to the foregoing relationship, a fine structure such as an uneven surface arrangement of other lenses may be additionally designed for the lens to enhance control of system performance and/or resolution. It should be noted that such details need to be selectively combined and applied to other embodiments of the invention without conflict.

In summary, the longitudinal spherical aberration, field curvature aberration, and distortion of the embodiments of the present invention all conform to the usage specifications. In addition, 643 nm (red light), 542 nm (green light), and 466 nm (blue light) three kinds of off-axis rays with different wavelengths at different heights are concentrated near the imaging point, and the skew of each curve can be It can be seen that the imaging point deviations of off-axis rays of different heights are controlled and have good spherical aberration, aberration and distortion suppression capability. Referring further to the imaging quality data, the distances of the three representative wavelengths of 643 nm, 542 nm, and 466 nm are also relatively close to each other, showing that the embodiment of the present invention has excellent concentration of light of different wavelengths in various states and has excellent performance. Since the dispersion suppressing ability is obtained, it is understood from the above that the embodiment of the present invention has good optical performance. Therefore, the eyepiece optical system of the embodiment of the present invention has both light and low stray light characteristics and has good optical imaging quality.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of protection of the present invention It is subject to the definition of the scope of the patent application attached.

Claims (6)

An eyepiece optical system for imaging imaging light from a display screen through an eyepiece optical system into an observer's eye, a direction toward the eye being a side, and a direction toward the display being a display side, the eyepiece optical system including a lens having a mesh side facing the mesh side and passing the imaging light and a display side facing the display side and passing the imaging light; the lens has an optical axis from the display side to the side Extendingly, the display side of the lens adopts a Fresnel lens design, and the display side has a plurality of effective sub-surfaces and a plurality of invalid sub-surfaces for imaging the imaging light, each invalid sub-surface connection Adjacent two effective sub-surfaces, and the eyepiece optical system conforms to: 1.500 ≦ R1/SagI ≦ 4.000, where SagI is the sum of the lengths of the plurality of vertical projections of the effective sub-surfaces on the optical axis, respectively, and R1 The optical effective radius of the side of the display. The eyepiece optical system of claim 1, wherein the eyepiece optical system is more compatible with 1.700 ≦ R1/SagI ≦ 3.200. The eyepiece optical system according to claim 2, wherein the eyepiece optical system is more in conformity with 1.360 ≦ ICD/EFL ≦ 1.630, wherein the ICD is a display image circle of the display screen corresponding to the maximum viewing angle of the single eye of the observer The diameter, and the EFL is the system focal length of the eyepiece optical system. The eyepiece optical system of claim 2, wherein the eyepiece optical system is more in accordance with 29.000 ∘≦ α ≦ 48.500 ∘, where α is the maximum tilt of the effective sub-surfaces relative to a reference plane perpendicular to the optical axis. angle. The eyepiece optical system of claim 1, wherein the eyepiece optical system is more in accordance with 25.000 ∘≦ α ≦ 52.000 ∘, wherein α is the maximum tilt of the effective sub-surfaces with respect to a reference plane perpendicular to the optical axis. angle. The eyepiece optical system of claim 1, wherein the display side of the lens is a planar Fresnel surface.