Collimator lens and optical scanner device which uses such collimator lens

• US 6,014,262 A
• Filed: 12/08/1998
• Issued: 01/11/2000
• Est. Priority Date: 01/09/1998
• Status: Expired due to Fees

• Current Assignee: Fuji Photo Optical Co. Ltd (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Optical Co. Ltd (Fujifilm Holdings Corporation)
• Inventors: Noda, Takayuki
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): Lester, Evelyn A.
• Application Number:
  US09/206,558
• Time in Patent Office: 399 Days
• Field of Search: 359/205, 359/641, 359/659, 359/662, 359/714, 359/739, 359/753, 359/763, 359/770
• US Class Current: 359/641
• CPC Class Codes: G02B 26/124 Details of the optical system between the light source and the polygonal mirror G02B26/123, G02B26/127 take precedence

Abstract

A collimator lens having five lens elements of negative, negative, positive, positive, and negative refractive power, in order from a collimated luminous flux side of the collimator lens, and designed to have a large back focus, to thereby prevent heat from the light source from causing aberrations in the collimator lens. The collimator lens includes a negative first lens element L₁ of a meniscus shape with its concave surface on the collimated luminous flux side, a positive fourth lens element L₄ with a convex surface on the collimated luminous flux side, and a negative fifth lens element L₅ with a concave surface on the collimated luminous flux side. In addition, a diaphragm stop is arranged on the collimated luminous flux side of the first lens element, and certain conditions are satisfied to reduce aberrations and provide a large back focus.

Claims

1. A collimator lens comprising, in order from a collimated luminous flux side of the collimator lens:

a first lens element of negative refractive power,

a second lens element of negative refractive power,

a third lens element of positive refractive power,

a fourth lens element of positive refractive power,

a fifth lens element of negative refractive power, and

a diaphragm arranged on the collimated luminous flux side of said first lens element.

2. The collimator lens of claim 1, wherein said first lens element has a meniscus shape with its concave surface on the collimated luminous flux side.

3. The collimator lens of claim 2, wherein the fourth lens element has a convex surface on the collimated luminous flux side.

4. The collimator of claim 3, wherein the fifth lens element has a concave surface on the collimated luminous flux side.

5. The collimator lens according to claim 1, and further satisfying the following condition

6. The collimator lens according to claim 5, said collimator lens further satisfying the following conditions:

space="preserve" listing-type="equation">-0.79<

R.sub.1 /f<

-0.70

space="preserve" listing-type="equation">1.10<

f.sub.4 /f<

1.94

where R₁ is the radius of curvature on the collimated luminous flux side of the first lens element, f is the focal length of the collimator lens, and f₄ is the focal length of the fourth lens element.

7. The collimator lens according to claim 6, said collimator lens further satisfying the following conditions:

space="preserve" listing-type="equation">1.2<

f.sub.3 /f<

1.60

space="preserve" listing-type="equation">0.80<

f.sub.2 /f.sub.1 <

1.2

where f₃ is the focal length of the third lens element, f is the focal length of the collimator lens, f₂ is the focal length of the second lens element, and f₁ is the focal length of the first lens element.

8. The collimator lens according to claim 1, said collimator lens further satisfying the following conditions:

space="preserve" listing-type="equation">-0.79<

R.sub.1 /f<

-0.70

space="preserve" listing-type="equation">1.10<

f.sub.4 /f<

1.94

where R₁ is the radius of curvature on the collimated luminous flux side of the first lens element, f is the focal length of the collimator lens, and f₄ is the focal length of the fourth lens element.

9. The collimator lens as set forth in claim 1, said collimator lens further having the following construction:

space="preserve" listing-type="tabular">______________________________________ # R D N ν

.sub.d ______________________________________ S ∞

6.65 1 -74.11 28.75 1.539 45.8 2 -140.86 11.02 3 245.86 8.31 45.8 4 104.51 39.51 5 162.53 45.48 1.610 63.3 6 -133.61 8.19 7 110.38 27.02 1.610 63.3 8 -3525.89 8.42 9 -155.09 8.03 45.8 10 -3630.59 ______________________________________

where S is a stop, # is the surface number in order from the side of the collimated luminous flux, R is the radius of curvature in mm of each lens element surface, D is the on-axis surface spacing in mm, N is the index of refraction at λ

=830 nm, and ν

_d is the Abbe number for the d-line of each lens element.

10. The collimator lens as set forth in claim 1, said collimator lens further having the following construction:

space="preserve" listing-type="tabular">______________________________________ # R D N ν

.sub.d ______________________________________ S ∞

5.56 1 -76.54 25.95 1.546 45.8 2 -127.69 14.83 3 212.35 12.47 1.546 45.8 4 106.35 39.59 5 158.44 49.53 1.616 63.3 6 -158.44 13.65 7 103.37 44.31 1.616 63.3 8 18244.38 8.93 9 -150.51 11.96 1.546 45.8 10 -9838.72 ______________________________________

where S is a stop, # is the surface number in order from the side of the collimated luminous flux, R is the radius of curvature in mm of each lens element surface, D is the on-axis surface spacing in mm, N is the index of refraction at λ

=632.8 nm, and ν

_d is the Abbe number for the d-line of each lens element.

11. The collimator lens as set forth in claim 1, said collimator lens further having the following construction:

space="preserve" listing-type="tabular">______________________________________ # R D N ν

.sub.d ______________________________________ S ∞

6.38 1 -73.87 29.68 1.539 45.8 2 -146.32 10.11 3 258.25 6.82 45.8 4 105.04 39.49 5 167.74 44.69 1.610 63.3 6 -128.17 6.67 7 114.39 21.4 63.3 8 -2088.16 7.67 9 -160.78 6.67 45.8 10 -2594.99 ______________________________________

where S is a stop, # is the surface number in order from the side of the collimated luminous flux, R is the radius of curvature in mm of each lens element surface, D is the on-axis surface spacing in mm, N is the index of refraction at λ

=830 nm, and ν

_d is the Abbe number for the d-line of each lens element.

12. The collimator lens as set forth in claim 1, said collimator lens further having the following construction:

space="preserve" listing-type="tabular">______________________________________ # R D N ν

.sub.d ______________________________________ S ∞

6.57 1 -71.97 32.97 1.539 45.8 2 -162.53 6.67 3 306.64 6.67 45.8 4 102.27 38.68 5 195.18 41.29 1.610 63.3 6 -118.88 7.08 7 118.76 25.03 1.610 63.3 8 -1100.81 7.27 9 -167.13 6.67 45.8 10 -1542.34 ______________________________________

where S is a stop, # is the surface number in order from the side of the collimated luminous flux, R is the radius of curvature in mm of each lens element surface, D is the on-axis surface spacing in mm, N is the index of refraction at λ

=830 nm, and ν

_d is the Abbe number for the d-line of each lens element.

13. The collimator lens as set forth in claim 1, said collimator lens further having the following construction:

space="preserve" listing-type="tabular">______________________________________ # R D N ν

.sub.d ______________________________________ S ∞

7.31 1 -77.74 27.45 1.539 45.8 2 -117.21 15.99 3 186.48 14.50 1.539 45.8 4 107.08 36.84 5 161.03 50.87 1.610 63.3 6 -190.12 21.39 7 96.68 55.49 1.610 63.3 8 90867.37 14.41 9 -143.43 28.77 1.539 45.8 10 ∞

______________________________________

where S is a stop, # is the surface number in order from the side of the collimated luminous flux, R is the radius of curvature in mm of each lens element surface, D is the on-axis surface spacing in mm, N is the index of refraction at λ

=830 nm, and ν

_d is the Abbe number for the d-line of each lens element.

14. In an optical scanner, the improvement of a collimator lens as set forth in claim 1.

15. In an optical scanner, the improvement of a collimator lens as set forth in claim 2.

16. In an optical scanner, the improvement of a collimator lens as set forth in claim 3.

17. In an optical scanner, the improvement of a collimator lens as set forth in claim 4.

18. In an optical scanner, the improvement of a collimator lens as set forth in claim 5.

19. In an optical scanner, the improvement of a collimator lens as set forth in claim 6.

20. In an optical scanner, the improvement of a collimator lens as set forth in claim 7.