FIXED-FOCUS LENS

• US 20100232038A1
• Filed: 12/21/2009
• Published: 09/16/2010
• Est. Priority Date: 03/12/2009
• Status: Active Grant

• Current Assignee: Young Optics, Inc. (Coretronic Corporation)
• Original Assignee: Young Optics, Inc. (Coretronic Corporation)
• Inventors: Su, Yuan-Hung, Kang, Yi-Hao
• Granted Patent: US 8,054,541 B2
• Time in Patent Office: Days
• US Class Current: 359/717
• CPC Class Codes: G02B 13/06 Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
• CPC Class Codes: G02B 13/16 for use in conjunction with image converters or intensifiers , or for use with projectors, e.g. objectives for projection TV
• CPC Class Codes: G02B 17/08 Catadioptric systems used in non-imaging applications G02B19/00
• CPC Class Codes: G02B 17/0852 having a field corrector only

Abstract

A fixed-focus lens adapted to be disposed between a primary image side and a second image side is provided. The fixed-focus lens includes a second lens group, a first lens group, and a curved reflector arranged in sequence from the primary image side to the second image side. The second lens group includes a first lens, a second lens, and a third lens arranged in sequence from the primary image side to the second image side. The first lens and the third lens have positive refractive powers and each of the first lens, the second lens, and the third lens is a spherical lens.

Claims

1. A fixed-focus lens, adapted to be disposed between a primary image side and a second image side and having an optical axis, the fixed-focus lens comprising:

a first lens group disposed between the primary image side and the second image side and comprising an aspheric lens;

a second lens group disposed in a light path between the primary image side and the first lens group and comprising a first lens, a second lens, and a third lens sequentially arranged from the primary image side to the second image side, wherein refractive powers of the first lens and the third lens are both positive, and each of the first lens, the second lens, and the third lens is a spherical lens; and

a curved reflector disposed in a light path between the primary image side and the second image side, wherein a refractive power of the curved reflector is negative;

wherein an image light beam transmitted from the primary image side and passing through the first lens group and the second lens group forms one of a butterfly-like spot and a trapezoid-like spot on a reference plane, and the reference plane is located between the first lens group and the curved reflector and perpendicular to a part of the optical axis between the first lens group and the curved reflector;

wherein the image light beam forming the butterfly-like spot is compensated to form a rectangular spot after being reflected by the curved reflector, and the image light beam forming the trapezoid-like spot is compensated to form another rectangular spot after being reflected by the curved reflector.

2. The fixed-focus lens as claimed in claim 1, wherein the reference plane passes through a center position between the first lens group and the curved reflector.

3. The fixed-focus lens as claimed in claim 1, further comprising a light valve, wherein an offset of the light valve relative to the optical axis is greater than or equal to 100%.

4. The fixed-focus lens as claimed in claim 1, wherein the image light beam is capable of passing through the first lens group and the second lens group, and a distance between a near axial ray focus of the image light beam and the first lens group is shorter than a distance between an off-axis ray focus of the image light beam and the first lens group.

5. The fixed-focus lens as claimed in claim 1, wherein the second lens group comprises a fixed lens group and a movable lens group, wherein the fixed lens group is fixed with respect to the fixed-focus lens, and the movable lens group is capable of moving with respect to the fixed-focus lens to focus.

6. The fixed-focus lens as claimed in claim 1, wherein the second lens group comprises at least one low dispersion lens having Abbe number greater than 75, and a refractive index of the at least one low dispersion lens is less than 1.55.

7. The fixed-focus lens as claimed in claim 1, wherein the second lens group comprises the first lens, the second lens, the third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged in sequence from the primary image side to the second image side, refractive powers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are respectively positive, negative, positive, negative, positive, negative, positive, and negative, wherein each of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens is a spherical lens, and the eighth lens is an aspheric lens.

8. The fixed-focus lens as claimed in claim 7, wherein each of the first lens, the third lens, the fifth lens, and the seventh lens is a biconvex lens, each of the second lens and the eighth lens is a convex-concave lens with a convex surface facing the second image side, the fourth lens is a convex-concave lens with a convex surface facing the primary image side, and the sixth lens is a biconcave lens, wherein the first lens and the second lens together form a first double cemented lens, and the fifth lens and the sixth lens together form a second double cemented lens.

9. The fixed-focus lens as claimed in claim 1, wherein the first lens group comprises a ninth lens, and a refractive power of the ninth lens is negative, wherein the ninth lens is an aspheric lens.

10. The fixed-focus lens as claimed in claim 1, wherein the second lens group comprises the first lens, the second lens, the third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, and a tenth lens arranged in sequence from the primary image side to the second image side, refractive powers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, and the tenth lens are respectively positive, positive, positive, negative, positive, positive, negative, positive, positive, and negative, wherein each of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, and the tenth lens is a spherical lens.

11. The fixed-focus lens as claimed in claim 10, wherein each of the first lens and the ninth lens is a concave-convex lens with a convex surface facing the second image side, each of the second lens, the sixth lens, and the eighth lens is a biconvex lens, each of the third lens and the fifth lens is a concave-convex lens with a convex surface facing the primary image side, the fourth lens is a convex-concave lens with a convex surface facing the primary image side, the seventh lens is a biconcave lens, and the tenth lens is a convex-concave lens with a convex surface facing the second image side.

12. The fixed-focus lens as claimed in claim 1, wherein the first lens group comprises a eleventh lens and a twelfth lens arranged in sequence from the primary image side to the second image side, refractive powers of the eleventh lens and the twelfth lens are respectively positive and negative, wherein each of the eleventh lens and the twelfth lens is an aspheric lens.

13. The fixed-focus lens as claimed in claim 1, wherein the second lens group comprises the first lens, the second lens, the third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged in sequence from the primary image side to the second image side, refractive powers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens are respectively positive, positive, positive, negative, positive, negative, positive, positive, and negative, wherein each of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, and the ninth lens is a spherical lens.

14. The fixed-focus lens as claimed in claim 13, wherein each of the first lens, the seventh lens, and the eighth lens is a concave-convex lens with a convex surface facing the second image side, each of the second lens and the fifth lens is a biconvex lens, the third lens is a concave-convex lens with a convex surface facing the primary image side, the fourth lens is a convex-concave lens with a convex surface facing the primary image side, the sixth lens is a biconcave lens, and the ninth lens is a convex-concave lens with a convex surface facing the second image side.

15. The fixed-focus lens as claimed in claim 1, wherein the first lens group comprises a tenth lens and a eleventh lens arranged in sequence from the primary image side to the second image side, refractive powers of the tenth lens and the eleventh lens are respectively positive and negative, wherein each of the tenth lens and the eleventh lens is an aspheric lens.

16. The fixed-focus lens as claimed in claim 1, wherein the second lens group comprises the first lens, the second lens, the third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged in sequence from the primary image side to the second image side, refractive powers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are respectively positive, negative, positive, negative, positive, negative, and positive, wherein each of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens is a spherical lens.

17. The fixed-focus lens as claimed in claim 16, wherein each of the first lens and the third lens is a biconvex lens, the second lens is a convex-concave lens with a convex surface facing the second image side, each of the fourth lens and the sixth lens is a convex-concave lens with a convex surface facing the primary image side, the fifth lens is a concave-convex lens with a convex surface facing the primary image side, and the seventh lens is a biconvex lens, wherein the first lens and the second lens together form a first double cemented lens, and the fourth lens and the fifth lens together form a second double cemented lens.

18. The fixed-focus lens as claimed in claim 1, wherein the first lens group comprises an eighth lens, a ninth lens, a tenth lens, and a eleventh lens arranged in sequence from the primary image side to the second image side, refractive powers of the eighth lens, the ninth lens, the tenth lens, and the eleventh lens are respectively negative, negative, negative, and negative, wherein each of the eighth lens, the ninth lens, and the tenth lens is a spherical lens, and the eleventh lens is an aspheric lens.

19. The fixed-focus lens as claimed in claim 1, further comprising an aperture stop disposed in a light path within the second lens group.

20. A fixed-focus lens, adapted to be disposed between a primary image side and a second image side and having an optical axis, wherein a light valve is adapted to be disposed at the primary image side and capable of emitting an image light beam, the fixed-focus lens comprising:

a first lens group disposed between the primary image side and the second image side and comprising an aspheric lens;

a second lens group disposed in a light path between the primary image side and the first lens group and comprising a first lens, a second lens, and a third lens sequentially arranged from the primary image side to the second image side, wherein refractive powers of the first lens and the third lens are both positive, and each of the first lens, the second lens, and the third lens is a spherical lens; and

a curved reflector disposed in a light path between the primary image side and the second image side, wherein a refractive power of the curved reflector is negative;

wherein the image light beam passing through the first lens group and the second lens group forms one of a first type spot and a second type spot on a reference plane, and the reference plane is located between the first lens group and the curved reflector and perpendicular to a part of the optical axis between the first lens group and the curved reflector;

wherein the image light beam forming the first type spot is compensated to form a rectangular spot after being reflected by the curved reflector, and the image light beam forming the second type spot is compensated to form another rectangular spot after being reflected by the curved reflector;

wherein the first type spot comprises a first butterfly-like reference point (a), a second butterfly-like reference point (b), a third butterfly-like reference point (c), a fourth butterfly-like reference point (d), a fifth butterfly-like reference point (e), a sixth butterfly-like reference point (f), a seventh butterfly-like reference point (g), an eighth butterfly-like reference point (h), a ninth butterfly-like reference point (i), a tenth butterfly-like reference point (j), a eleventh butterfly-like reference point (k), a twelfth butterfly-like reference point (m), and a thirteenth butterfly-like reference point (n), and a first image point (A), a second image point (B), a third image point (C), a fourth image point (D), a fifth image point (E), a sixth image point (F), a seventh image point (G), an eighth image point (H), a ninth image point (I), a tenth image point (J), a eleventh image point (K), a twelfth image point (M), and a thirteenth image point (N) on the light valve respectively form the butterfly-like reference points after being imaged by the first lens group and the second lens group, wherein a relationship of the butterfly-like reference points and the image points satisfies at least one of a first condition and a second condition as follows;

$\mathrm{the}<br><br><br><br>\mathrm{first}<br><br><br><br>\mathrm{condition}<br><br>\text{;<br><br>}<br><br><br><br>\stackrel{\_}{a<br><br><br><br>c}+\stackrel{\_}{\mathrm{gi}}><br><br>2\times <br><br>\stackrel{\_}{\mathrm{df}},\stackrel{\_}{\mathrm{ag}}><br><br>\stackrel{\_}{\mathrm{bh}}><br><br>\stackrel{\_}{\mathrm{ci}},<br><br>\stackrel{\_}{\mathrm{BE}}=2<br><br>\stackrel{\_}{\mathrm{BJ}},\stackrel{\_}{\mathrm{CF}}=2<br><br>\stackrel{\_}{\mathrm{CK}},\stackrel{\_}{\mathrm{bc}}\approx <br><br>\stackrel{\_}{\mathrm{jk}},\stackrel{\_}{\mathrm{EH}}=2<br><br>\stackrel{\_}{\mathrm{MH}},\stackrel{\_}{\mathrm{FI}}=2<br><br>\stackrel{\_}{\mathrm{NI}},<br><br>\mathrm{and}<br><br><br><br>\stackrel{\_}{\mathrm{mn}}\approx <br><br>\stackrel{\_}{\mathrm{hi}};<br><br>$ $\mathrm{the}<br><br><br><br>\mathrm{second}<br><br><br><br>\mathrm{condition}<br><br>\text{;<br><br>}<br><br><br><br>5><br><br>\frac{\stackrel{\_}{a<br><br><br><br>c}+\stackrel{\_}{\mathrm{gi}}}{2\times <br><br>\stackrel{\_}{\mathrm{df}}}><br><br>1,0.1\le <br><br>\frac{\stackrel{\_}{\mathrm{bh}}}{\stackrel{\_}{\mathrm{ag}}}<<br><br>1,<br><br>0.1\le <br><br>\frac{\stackrel{\_}{\mathrm{ci}}}{\stackrel{\_}{\mathrm{bh}}}<<br><br>1,0.9\le <br><br>\frac{\stackrel{\_}{\mathrm{bc}}}{\stackrel{\_}{\mathrm{jk}}}<<br><br>1.1,0.9\le <br><br>\frac{\stackrel{\_}{\mathrm{hi}}}{\stackrel{\_}{\mathrm{mn}}}<<br><br>1.1,\stackrel{\_}{\mathrm{ef}}<<br><br>\stackrel{\_}{\mathrm{jk}},<br><br>\mathrm{and}<br><br><br><br>\stackrel{\_}{\mathrm{ef}}<<br><br>\stackrel{\_}{\mathrm{mn}};<br><br>$

wherein the second type spot comprises a first trapezoid-like reference point (a′

), a second trapezoid-like reference point (b′

), a third trapezoid-like reference point (c′

), a fourth trapezoid-like reference point (d′

), a fifth trapezoid-like reference point (e′

), a sixth trapezoid-like reference point (f′

), a seventh trapezoid-like reference point (g′

), an eighth trapezoid-like reference point (h′

), and a ninth trapezoid-like reference point (i′

), and the first image point (A), the second image point (B), the third image point (C), the fourth image point (D), the fifth image point (E), the sixth image point (F), the seventh image point (G), the eighth image point (H), and the ninth image point (I) on the light valve respectively form the trapezoid-like reference points after being imaged by the first lens group and the second lens group, wherein a relationship of the trapezoid-like reference points and the image points satisfies a third condition as follows;

$\mathrm{the}<br><br><br><br>\mathrm{third}<br><br><br><br>\mathrm{condition}<br><br>\text{;<br><br>}<br><br><br><br>1.05><br><br>\frac{\stackrel{\_}{a^{\mathrm{\prime <br><br>}}<br><br>c^{\mathrm{\prime <br><br>}}}+\stackrel{\_}{g^{\mathrm{\prime <br><br>}}<br><br>i^{\mathrm{\prime <br><br>}}}}{2\times <br><br>\stackrel{\_}{d^{\mathrm{\prime <br><br>}}<br><br>f^{\mathrm{\prime <br><br>}}}}><br><br>0.95,0.1\le <br><br>\frac{\stackrel{\_}{b^{\mathrm{\prime <br><br>}}<br><br>h^{\mathrm{\prime <br><br>}}}}{\stackrel{\_}{a^{\mathrm{\prime <br><br>}}<br><br>g^{\mathrm{\prime <br><br>}}}}<<br><br>1,<br><br>\mathrm{and}<br><br><br><br>0.1\le <br><br>\frac{\stackrel{\_}{c^{\mathrm{\prime <br><br>}}<br><br>i^{\mathrm{\prime <br><br>}}}}{\stackrel{\_}{b^{\mathrm{\prime <br><br>}}<br><br>h^{\mathrm{\prime <br><br>}}}}<<br><br>1.$

21. A fixed-focus lens, adapted to be disposed between a primary image side and a second image side and having an optical axis, the fixed-focus lens comprising:

a first lens group disposed between the primary image side and the second image side and comprising an aspheric lens;

a second lens group disposed in a light path between the primary image side and the first lens group and comprising a first lens, a second lens, and a third lens sequentially arranged from the primary image side to the second image side, wherein refractive powers of the first lens and the third lens are both positive, and each of the first lens, the second lens, and the third lens is a spherical lens; and

a curved reflector disposed in a light path between the primary image side and the second image side, wherein a refractive power of the curved reflector is negative;

wherein an effective focal length (EFL) of the fixed-focus lens is F, an EFL of the first lens group is F₁, and an EFL of the second lens group is F₂, and the fixed-focus lens satisfies at least one of following conditions;

8.5<

|F₁/F|<

50.1 and 20.2<

|F₂/F|<

75.7.