Projection lenses having reduced lateral color for use with pixelized panels

• US 6,195,209 B1
• Filed: 05/04/1999
• Issued: 02/27/2001
• Est. Priority Date: 05/04/1999
• Status: Expired due to Term

• Current Assignee: Regents of The University of Minnesota (University of Minnesota)
• Original Assignee: US Precision Lens, Inc. (3M Company)
• Inventors: Moskovich, Jacob, Kreitzer, Melvyn H.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): THOMPSON, TIMOTHY J
• Application Number:
  US09/304,693
• Time in Patent Office: 665 Days
• Field of Search: 359/649, 359/650, 359/651, 359/689, 359/691
• US Class Current: 359/649
• 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 13/22 Telecentric objectives or lens systems

Abstract

Projection lens for use with pixelized panels are provided which consist of a first lens unit which has a negative power and a second lens unit which has a positive power. The V-values and Q-values of the lens elements of the first and second lens units are selected so that the projection lenses can simultaneously have: (1) a high level of lateral color correction, including correction of secondary lateral color; (2) low distortion; (3) a large field of view in the direction of the image (screen); (4) a telecentric entrance pupil; and (5) a relatively long back focal length.

Claims

1. A projection lens for forming an image of an object which consists in order from its image end to its object end of:

(A) a first lens unit U₁ having a negative power and comprising three lens elements E_P, E_N, and E_N′

, arranged in any order and having focal lengths f_U1/P, f_U1/N, and f_U1/N′

, V-values V_U1/P, V_U1/N, and V_U1/N′

, and Q-values Q_U1/P, Q_U1/N, and Q_U1/N′

, respectively;

(B) a second lens unit having a positive power; and

(C) an optional field lens unit;

wherein E_N or E_N′

is made of glass and wherein;

f_U1/P>

0,

f_U1/N<

0,

f_U1/N′

<

0,

V_U1/N>

V_U1/P,

V_U1/N′

>

V_U1/P,

Q_U1/N>

0,

Q_U1/N>

Q_U1/P,

Q_U1/N>

V_U1/N,

Q_U1/N′

>

0, and

Q_U1/N>

Q_U1/P.

2. The projection lens of claim 1 wherein Q_U1/N′

>

V_U1/N.

3. The projection lens of claim 1 wherein Q_U1/P<

0.

9. The projection lens of claim 1, 4, 5, 6, 7, or 8 wherein:

10. The projection lens of claim 1, 4, 5, 6, or 8 wherein the projection lens has an aperture stop or a pseudo-aperture stop and the first lens unit is on the image side of said aperture stop or pseudo-aperture stop and the second lens unit is on the object side of said aperture stop or pseudo-aperture stop.

11. The projection lens of claim 1 wherein the projection lens has an aperture stop or a pseudo-aperture stop and E_P, E_N, and E_N′

are on the image side of said aperture stop or pseudo-aperture stop.

14. The projection lens of claim 1, 4, 5, 6, 7, or 8 wherein the projection lens is telecentric in the direction of the object.

15. The projection lens of claim 1, 4, 5, 6, 7, or 8 wherein the first lens unit comprises an aspherical surface.

16. The projection lens of claim 1, 4, 5, 6, 7, or 8 wherein the second lens unit comprises an aspherical surface.

17. The projection lens of claim 1, 4, 5, 6, 7, or 8 wherein the lens is a zoom lens.

18. The projection lens of claim 1, 4, 5, or 8 wherein the second lens unit comprises two lens elements E′

_P and E′

_N, arranged in any order and having focal lengths f_U2/P and f_U2/N, V-values V_U2/P and V_U2/N, and Q-values Q_U2/P and Q_U2/N, respectively, where;

f_U2/P>

0,

f_U2/N<

0,

V_u2/P>

V_U2/N,

Q_U2/P>

0,

Q_U2/P>

Q_U2/N, and

Q_U2/P>

V_U2/P.

19. The projection lens of claim 18 wherein:

20. The projection lens of claim 18 wherein:

21. A projection lens system for forming an image of an object, said system comprising:

(a) an illumination system comprising a light source and illumination optics which forms an image of the light source, said image of the light source being the output of the illumination system;

(b) a pixelized panel which comprises the object; and

(c) the projection lens of claim 1, 4, 5, 6, 7, or 8.

22. The projection lens system of claim 21 wherein said projection lens has an entrance pupil whose location substantially corresponds to the location of the output of the illumination system.

23. The projection lens system of claim 21 wherein the projection lens is a zoom lens.

24. The projection lens of claim 1, 4, 5, or 8 wherein E_P and E_N or E_N′

form a color correcting doublet.

4. A projection lens for forming an image of an object which consists in order from its image end to its object end of:

(A) a first lens unit U₁ having a negative power and comprising two lens elements E_P and E_N, arranged in any order and having focal lengths f_U1/P and f_U1/N, V-values V_U1/P and V_U1/N, and Q-values Q_U1/P and Q_U1/N, respectively;

(B) a second lens unit having a positive power; and

(C) an optional field lens unit;

wherein E_N is made of glass and wherein;

f_U1/P>

0,

f_U1/N<

0,

V_U1/N>

V_U1/P,

Q_U1/N>

0, and

Q_U1/P<

0.

12. The projection lens of claim 4 or 5 wherein the projection lens has an aperture stop or a pseudo-aperture stop and E_P and E_N are on the image side of said aperture stop or pseudo-aperture stop.

5. A projection lens for forming an image of an object which consists in order from its image end to its object end of:

(A) a first lens unit U₁ having a negative power and comprising two lens elements E_P and E_N, arranged in any order and having focal lengths f_U1/P and f_U1/N, V-values V_U1/P and V_U1/N, and Q-values Q_U1/P and Q_U1/N, respectively;

(B) a second lens unit having a positive power; and

(C) an optional field lens unit;

wherein;

f_U1/P>

0,

V_U1/N>

V_U1/P,

Q_U1/N>

V_U1/N, and

Q_U1/N>

125.

6. A projection lens for forming an image of an object which consists in order from its image end to its object end of:

(A) a first lens unit U₁ having a negative power;

(B) a second lens unit U₂ having a positive power and comprising two lens elements E′

_P and E′

_N, arranged in any order and having focal lengths f_U2/P and f_U2/N, V-values V_U2/P and V_U2/N, and Q-values Q_U2/P and Q_U2/N, respectively; and

(C) an optional field lens unit;

wherein;

f_U2/P>

0,

f_U2/N<

0,

V_U2/P>

V_U2/N,

Q_U2/P>

V_U2/P, and

Q_U2/P>

135.

13. The projection lens of claim 6 wherein the projection lens has an aperture stop or a pseudo-aperture stop and E′

_P and E′

_N are on the object side of said aperture stop or pseudo-aperture stop.

7. A projection lens for forming an image of an object composed of pixels, said projection lens consisting in order from its image end to its object end of:

(A) a first lens unit U₁ having a negative power;

(B) an aperture stop or a pseudo-aperture stop;

(C) a second lens unit U₂ having a positive power and comprising a positive lens elements having a V-value V_U2/P; and

(D) an optional field lens unit;

wherein;

V_U2/P>

75, and

V_U2/C>

0.1/(p′

•

F#_U2),

where F#_U2 is the f-number of the second lens unit as traced from the object towards the image, p′

is the width of a pixel divided by f₀, where f₁ is the focal length of the combination of the first and second lens units, and V_U2/C is a composite V-value for the second lens unit given by;

8. A projection lens for forming an image of an object composed of pixels, said projection lens consisting in order from its image end to its object end of:

(A) a first lens unit having a negative power and comprising means for correcting the secondary lateral color of the projection lens, said means comprising two lens elements E_P and E_N, arranged in any order and having focal lengths f_U1/P and f_U1/N, V-values V_U1/P and V_U1/N, and Q-values Q_U1/P and Q_U1/N. respectively;

(B) a second lens unit having a positive power; and

(C) an optional field lens unit;

wherein;

f_U1/P>

0,

f_U1/N<

0,

V_U1/N>

V_U1/P,

Q_U1/N>

0, and

Q_U1/P<

0.

25. A projection lens for forming an image of an object composed of pixels, said projection lens consisting in order from its image end to its object end of:

(A) a first lens unit having a negative power;

(B) a second lens unit having a positive power; and

(C) an optional field lens unit;

wherein;

(i) the projection lens has a half field of view in the direction of the image of at least 25°

;

(ii) the lateral color blur of the projection lens at its full field is less than a pixel for wavelengths in the range from 460 nanometers to 620 nanometers;

(iii) the distortion of the projection lens is less than 1.0 percent;

(iv) the projection lens is telecentric in the direction of the object;

(v) the projection lens is a zoom lens and has a short focal length position; and

(vi) the half field of view, lateral color blur, and distortion are evaluated at the short focal length position.

26. The projection lens of claim 25 wherein:

27. The projection lens of claim 25 wherein the projection lens has an aperture stop or a pseudo-aperture stop and the first lens unit is on the image side of said aperture stop or pseudo-aperture stop and the second lens unit is on the object side of said aperture stop or pseudo-aperture stop.

28. The projection lens of claim 25 wherein the first lens unit comprises an aspherical surface.

29. The projection lens of claim 25 wherein the second lens unit comprises an aspherical surface.

30. A projection lens system for forming an image of an object, said system comprising:

(a) an illumination system comprising a light source and illumination optics which forms an image of the light source, said image of the light source being the output of the illumination system;

(b) a pixelized panel which comprises the object; and

(c) the projection lens of claim 25.

31. The projection lens system of claim 30 wherein said projection lens has an entrance pupil whose location substantially corresponds to the location of the output of the illumination system.