CN102566044A - Optical imaging system adopting free-form surface prism - Google Patents

Abstract

The invention belongs to the technical field of virtual reality and particularly relates to an optical system applied to various virtual displayer products, such as glasses type virtual displayers, head-mounted virtual displayers and virtual stereoscopic displayers. The optical system comprises a free curved-surface prism and a compensator prism, wherein the top end of the optical system is provided with a micro displayer which is connected with video equipment through a driving circuit board for image display. Three optical surfaces of the free curved-face prism are all free curved faces and meet corresponding facial form equations, and the position relation among all the surfaces meets a corresponding coordinate conversion equation. The optical system is made of a PMMA plastic material, has the advantages of light weight, large view field, perspective property, favorable aberration correction performance and the like, and can present a clear magnified image in front of the eyes of people.

Description

A kind of optical imaging system that adopts free curved surface prism

Technical field

The present invention relates to adopt the optical imaging system of free curved surface prism, belong to the optical design field.Optical imaging system is installed on the head-mounted display the inside.

Background technology

(Head-Mounted Display, HMD) (Head-Up Display's head-mounted display HUD) develops, and is used for military use the earliest by head-up display.Head-mounted display is made up of three parts: Circuits System, optical system and support system.Head-mounted display the earliest adopts cathode-ray tube (CRT) as image source, along with development of technology, is replaced by liquid crystal on silicon and Organic Light Emitting Diode etc., and the integrated level of circuit is increasingly high, and this respect technology is comparative maturity.Realize the lightness and the miniaturization of head-mounted display, it is particularly important that Design for optical system just becomes.Traditional optical system optics parts are many, complex structure, and weight is big, causes very big burden to head, and light path is longer, and image quality descends, and the visual field is also less, and is the non-structure of looking, the design demand of incompatible current head-mounted display.

Summary of the invention

For overcoming all deficiencies of conventional optical systems, the present invention proposes the big emergent pupil in a kind of big visual field and looks the free form surface optical imaging system of formula, have light-duty, compactness, characteristics such as picture element is good.

The present invention realizes through following technical scheme:

A kind of optical imaging system that adopts free curved surface prism comprises a free curved surface prism and a compensating prism.Free curved surface prism comprises three free form surface optical surfaces, comprises the plane of incidence that is positioned at end face, realizes that optics enters in the optical system; Be positioned at the left side free form surface, will from the plane of incidence get into optical system the light total reflection and reflect away; Be positioned at the reflecting surface on right side,, reflect away at last and be aggregated to pupil the light that reflects back reflected back again.Compensating prism is positioned at the free curved surface prism right side, comprises two free form surface optical surfaces, is positioned at the face in left side, and the face type is identical with the face on free curved surface prism right side and overlap; Be positioned at the face on right side, the face type is identical and parallel with this face with the face in free curved surface prism left side.

Free curved surface prism in the optical imaging system of above-mentioned employing free form surface adopts three free form surfaces.

Free curved surface prism in the optical imaging system of above-mentioned employing free form surface adopts each power parameter designing, from first power to five powers.

The optical imaging system of above-mentioned employing free form surface is formed by plastic production.

The optical imaging system of above-mentioned employing free form surface is formed by free curved surface prism and compensating prism gummed.

The cemented surface of the optical imaging system of above-mentioned employing free form surface is coated with part reflective semitransparent film.

Three free form surfaces in the free curved surface prism all satisfy following equation

$z=\frac{{\mathrm{<figure-callout\; id="2"\; label="cr"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">cr</figure-callout>}}^2}{1+\sqrt{1-(1+k)c^2{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}}+\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{A}_i{E}_i(x,y).$

Wherein, z is the axial rise of z, and c is a vertex curvature, and k is surperficial circular cone coefficient, and k is 0 among the present invention.(x y) is power item about x and y to Ei, and Ai is a power item coefficient.

Description of drawings

Fig. 1 is an optical schematic diagram of the present invention

Fig. 2 is a modulation transfer function of the present invention

Fig. 3 is a grid distortion maps of the present invention

Embodiment

Specify below in conjunction with accompanying drawing.

The acquiescence coordinate system is set among the present invention: be z axle positive dirction to the right, upwards be y axle positive dirction, vertical plane is x axle positive dirction inwards.

Light is sent by OLED; Get into optical system by face 1 refraction, greater than the angle of total reflection, so light all reflexes to face 3 in face 2 place's incident angles; Because face 3 places are coated with the part part reflective semitransparent film; Therefore part light reflexes to face 2, and incident angle is all less than the angle of total reflection at this moment, and light is able to refraction and gets into human eye.Extraneous light then can get into optical system through face 5, and face 5 is parallel with face 2, has largely eliminated the skew and the inclination of light.

Because surface equation part coefficient is 0, so equation also can be write as following form:

$z=\frac{a(x^2+y^2)}{1+\sqrt{1-a^2(x^2+y^2)}}+\mathrm{by}+c{x}^2+\mathrm{<figure-callout\; id="2"\; label="d\; y"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">d</figure-callout>}{y}^{}{}^2+e{x}^{2}y+f{y}^3+{\mathrm{<figure-callout\; id="4"\; label="gx"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">gx</figure-callout>}}^4+{\mathrm{hx}}^2{y}^2+{\mathrm{iy}}^4+{\mathrm{jx}}^{4}y+{\mathrm{kx}}^2{y}^3+{\mathrm{ly}}^5$

Wherein

$a_1=-\frac{1}{150.839615}$ $a_2=-\frac{1}{78.787711}$ $a_3=-\frac{1}{36.733921}$

$b_1=\frac{-15.797051}{100}$ ${\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">b</figure-callout>}}_2=\frac{15.299208}{100}$ ${\mathrm{<figure-callout\; id="3"\; label="b"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">b</figure-callout>}}_3=\frac{16.562137}{100}$

$c_1=\frac{435.330192}{{100}^2}$ ${\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">c</figure-callout>}}_2=\frac{-38.132517}{{100}^2}$ ${\mathrm{<figure-callout\; id="3"\; label="c"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">c</figure-callout>}}_3=\frac{-6.829099}{{100}^2}$

$d_1=\frac{223.889331}{{100}^2}$ ${\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">d</figure-callout>}}_2=\frac{63.600946}{{100}^2}$ ${\mathrm{<figure-callout\; id="3"\; label="d"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">d</figure-callout>}}_3=\frac{51.861089}{{100}^2}$

$e_1=\frac{-4940.967766}{{100}^3}$ $e_2=\frac{-165.441138}{{100}^3}$ $e_3=\frac{43.621448}{{100}^3}$

$f_1=\frac{-3296.129596}{{100}^3}$ ${\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">f</figure-callout>}}_2=\frac{15.840865}{{100}^3}$ ${\mathrm{<figure-callout\; id="3"\; label="f"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">f</figure-callout>}}_3=\frac{-30.320790}{{100}^3}$

$g_1=\frac{7065.991379}{{100}^4}$ ${\mathrm{<figure-callout\; id="2"\; label="g"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">g</figure-callout>}}_2=\frac{95.302015}{{100}^4}$ ${\mathrm{<figure-callout\; id="3"\; label="g"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">g</figure-callout>}}_3=\frac{-89.385239}{{100}^4}$

$h_1=\frac{-5283.339119}{{100}^4}$ ${\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">h</figure-callout>}}_2=\frac{-347.930573}{{100}^4}$ ${\mathrm{<figure-callout\; id="3"\; label="h"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">h</figure-callout>}}_3=\frac{39.399183}{{100}^4}$

$i_1=\frac{1.152394\&times;{10}^4}{{100}^4}$ $i_2=\frac{-200.337325}{{100}^4}$ $i_3=\frac{203.397669}{{100}^4}$

$j_1=\frac{9.062820\&times;{10}^4}{{100}^5}$ ${\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">j</figure-callout>}}_2=\frac{-366.535926}{{100}^5}$ ${\mathrm{<figure-callout\; id="3"\; label="j"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">j</figure-callout>}}_3=\frac{-127.360025}{{100}^5}$

$k_1=\frac{1.035241\&times;{10}^5}{{100}^5}$ ${\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">k</figure-callout>}}_2=\frac{-1280.388194}{{100}^5}$ ${\mathrm{<figure-callout\; id="3"\; label="k"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">k</figure-callout>}}_3=\frac{561.713627}{{100}^5}$

$l_1=\frac{-1.298383\&times;{10}^4}{{100}^5}$ ${\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">l</figure-callout>}}_2=\frac{362.365061}{{100}^5}$ ${\mathrm{<figure-callout\; id="3"\; label="l"\; filenames="HSA00000394740700011.png"\; state="\{\{state\}\}">l</figure-callout>}}_3=\frac{631.956581}{{100}^5}$

Three curved surfaces adopt different coordinate systems when satisfying above-mentioned equation.Curved surface 2 adopts the acquiescence coordinate system.Curved surface 3 coordinate systems are obtained by curved surface 2 coordinate system transformations: at z axial translation 4.959937mm, afterwards around 32 ° of x axle rotations.Curved surface 1 coordinate system is obtained by curved surface 2 coordinate system transformations: rotate-25 ° around the x axle, again translation 23.796769mm on Z is axial.

This optical system reaches following optical index

Field angle reaches 56 °

Exit pupil diameter is 8mm

The emergent pupil distance is 25mm

Modulation transfer function reaches 0.4 at the 20lp/mm place

Marginal distortion is 8%

Claims (6)

1. an optical imaging system that adopts free curved surface prism is characterized in that: comprise a free curved surface prism and a compensating prism.Free curved surface prism comprises three free form surface optical surfaces, comprising: be positioned at the plane of incidence 1 of end face, realize that optics enters in the optical system; Be positioned at the free form surface 2 in left side, will also reflect away from the light total reflection of the plane of incidence 1 entering optical system; Be positioned at the reflecting surface 3 on right side, the light that fully reflecting surface and face 2 are reflected back is reflected back fully reflecting surface and exit facet 2 again, is reflected away by fully reflecting surface and exit facet 2 at last and is aggregated to pupil.Compensating prism comprises two free form surface optical surfaces, comprising: be positioned at the face 4 in left side, face type and face 3 are identical and overlap; Be positioned at the face 5 on right side, the face type is identical and parallel with face 2 with face 2.

2. a kind of optical imaging system that adopts free form surface according to claim 1 is characterized in that: described free curved surface prism adopts three free form surfaces.

3. according to a kind of optical imaging system that adopts free form surface under the claim 1, it is characterized in that: described free curved surface prism adopts each power parameter designing, from first power to five powers.

4. a kind of optical imaging system that adopts free form surface according to claim 1, it is characterized in that: described lens are formed by plastic production.

5. a kind of optical imaging system that adopts free form surface according to claim 1 is characterized in that: described lens are formed by free curved surface prism and compensating prism gummed.

6. a kind of optical imaging system that adopts free form surface according to claim 1, it is characterized in that: cemented surface is coated with part reflective semitransparent film.

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