Objective lens system for an endscope

• US 4,674,844 A
• Filed: 07/24/1985
• Issued: 06/23/1987
• Est. Priority Date: 07/28/1984
• Status: Expired due to Term

• Current Assignee: Betz Laboratories, Inc. (General Electric Company), Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Inventors: Takahashi, Susumu, Nishioka, Kimihiko, Yokota, Akira, Okabe, Minoru
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Gass, Rebecca D.
• Application Number:
  US06/758,417
• Time in Patent Office: 699 Days
• Field of Search: 350/432, 350/469, 350/465, 350/450
• US Class Current: 359/782
• CPC Class Codes: G02B 23/243 Objectives for endoscopes
• CPC Class Codes: G02B 9/34 having four components only
• CPC Class Codes: G02B 9/60 having five components only

Abstract

An objective lens system for an endoscope comprises a first lens component having a negative refracting power, a second lens component having a positive refracting power, a third lens component having a positive refracting power and a fourth lens component involving a meniscus lens having its concave surface facing the object side, with the lens system being such that the total length is short, the outside diameter is small, the angle of view is wide, and the illuminance in the peripheral portion of the image field is high.

Claims

1. An objective lens system for an endoscope, comprising:

in order from the object side;

a first lens component having a negative refracting power, a second lens component having a positive refracting power, a third lens component having a positive refracting power, and a fourth lens component involving a meniscus lens having its concave surface facing the object side;

said objective lens system satisfying the following conditions (1), (2), (3) and (4);

space="preserve" listing-type="equation">|h.sub.1 f.sub.1 |>

1.15|h.sub.4 /f.sub.4 | (1)

space="preserve" listing-type="equation">F.sub.2 <

3.5 f (2)

space="preserve" listing-type="equation">|f.sub.4 |<

6 f (3)

space="preserve" listing-type="equation">-R.sub.2 ≦

15 f

     4)

wherein h₁ and h₄ represent the mean values of the heights of the principal ray at respective surfaces of said first lens component and said fourth lens component, f₁ and f₄ represent the focal lengths of the first lens component and the fourth lens component, respectively, f₂ represents the focal length of the second lens component, f represents the focal length of the objective lens system, and R₂ represents the radius of curvature of the image side surface of said second lens component.

2. An objective lens system for an endoscope according to claim 1, said third lens component being a cemented lens component, and further satisfying the following conditions (5) through (8):

space="preserve" listing-type="equation">|f.sub.1 |<

1.7 f (5)

space="preserve" listing-type="equation">|f.sub.23 |<

1.7 f (6)

space="preserve" listing-type="equation">R.sub.2 '"'"'>

0 (7)

space="preserve" listing-type="equation">R.sub.3 <

5 f (8)

space="preserve" listing-type="equation">|R.sub.3 '"'"'|<

3 f (9)

where f₂₃ represents the composite focal length of said second lens component and said third lens component, R₂ '"'"' represents the radius of curvature of said outermost surface of said second lens component towards the object, R₃ represents the radius of curvature of the outermost surface of the third lens component towards the object, R₃ '"'"' represents the radius of curvature of the cemented surface of said third lens component.

3. An objective lens system for an endoscope according to claim 2, said first lens component being a negative single lens, said second lens component being a biconvex lens, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.78 image height 1.0040 angle of view 115°

______________________________________ r.sub.1 = ∞

d.sub.1 = 0.2520 n.sub.1 = 1.51633 v.sub.1 = 64.15 r.sub.2 = 0.6655 d.sub.2 = 1.2601 r.sub.3 = 2.2444 d.sub.3 = 0.2520 n.sub.2 = 1.74100 v.sub.2 = 52.68 r.sub.4 = -6.8676 d.sub.4 = 0.0504 r.sub.5 = ∞

(aperture diaphragm) d.sub.5 = 0.0504 r.sub.6 = 2.5764 d.sub.6 = 0.5544 n.sub.3 = 1.62041 v.sub.3 = 60.27 r.sub.7 = -0.5040 d.sub.7 = 0.2016 n.sub.4 = 1.80518 v.sub.4 = 25.43 r.sub.8 = -0.9738 d.sub.8 = 0.7436 r.sub.9 = -0.6990 d.sub.9 = 0.2520 n.sub.5 = 1.72825 v.sub.5 = 28.46 r.sub.10 = -1.2601 h.sub.1 /f.sub.1 = 0.541 h.sub.4 /f.sub.4 = 0.184 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 2.94 f.sub.1 = -1.29 f.sub.2 = 2.31 f.sub.23 = 1.08 f.sub.4 = -2.66 R.sub.2 = -6.8676 R.sub.2 '"'"' = 2.2444 R.sub.3 = 2.5764 R.sub.3 '"'"' = -0.9738 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, and v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials.

4. An objective lens system for an endoscope according to claim 2, said first lens component being a negative single lens, said second lens component being a biconvex lens, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.14 image height 1.2102 angle of view 115°

______________________________________ r.sub.1 = 3.1235 d.sub.1 = 0.3038 n.sub.1 = 1.65160 v.sub.1 = 58.52 r.sub.2 = 0.7758 d.sub.2 = 1.5519 r.sub.3 = 1.7854 d.sub.3 = 0.3038 n.sub.2 = 1.74100 v.sub.2 = 52.68 r.sub.4 = -10.6273 d.sub.4 = 0.0608 r.sub.5 = ∞

(aperture diaphragm) d.sub.5 = 0.0608 r.sub.6 = 1.5013 d.sub.6 = 0.6683 n.sub.3 = 1.62041 v.sub.3 = 60.27 r.sub.7 = -0.6075 d.sub.7 = 0.2430 n.sub.4 = 1.80518 v.sub.4 = 25.43 r.sub.8 = -1.2264 d.sub.8 = 0.4860 r.sub.9 = -0.6198 d.sub.9 = 0.3038 n.sub.5 = 1.72825 v.sub.5 = 28.46 r.sub.10 = -1.8226 h.sub.1 /f.sub.1 = 0.558 h.sub.4 /f.sub.4 = 0.388 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 1.44 f.sub.1 = -1.67 f.sub.2 = 2.0846 f.sub.23 = 1.04 f.sub.4 = -1.44 R.sub.2 = -10.6273 R.sub.2 '"'"' = 1.7854 R.sub.3 = 1.5013 R.sub.3 '"'"' = -0.6075 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, and v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials.

5. An objective lens system for an endoscope according to claim 2, said first lens component being a negative single lens, said second lens component being a biconvex lens, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged in said second lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.228 image height 1.1914 angle of view 114°

______________________________________ r.sub.1 = 2.3923 d.sub.1 = 0.2990 n.sub.1 = 1.51633 v.sub.1 = 64.15 r.sub.2 = 0.5981 d.sub.2 = 1.0830 r.sub.3 = 2.5608 d.sub.3 = 0.2990 n.sub.2 = 1.74100 v.sub.2 = 52.68 r.sub.4 = ∞

(aperture diaphragm) d.sub.4 = 0.2990 n.sub.3 = 1.74100 v.sub.3 = 52.68 r.sub.5 = -1.6972 d.sub.5 = 0.0598 r.sub.6 = 2.4832 d.sub.6 = 0.2392 n.sub.4 = 1.71736 v.sub.4 = 29.51 r.sub.7 = 1.0766 d.sub.7 = 1.0391 n.sub.5 = 1.71300 v.sub.5 = 53.84 r.sub.8 = -2.0701 d.sub.8 = 0.3069 r.sub.9 = - 0.7419 d.sub.9 = 0.2990 n.sub.5 = 1.72825 v.sub.5 = 28.46 r.sub.10 = -2.4014 h.sub.1 /f.sub.1 = 0.479 h.sub.4 /f.sub.4 = 0.411 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 1.165 f.sub.1 = -1.64 f.sub.2 = 1.465 f.sub.23 = 1.02 f.sub.4 = -1.60 R.sub.2 = -1.6972 R.sub.2 '"'"' = 2.5608 R.sub.3 = 2.4832 R.sub.3 '"'"' = 1.0766 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, and v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials.

6. An objective lens system for an endoscope according to claim 2, said first lens component being a negative single lens, said second lens component being a biconvex lens, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a cemented lens component comprising a negative lens and a positive lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.781 image height 1.0091 angle of view 115°

______________________________________ r.sub.1 = ∞

d.sub.1 = 0.2533 n.sub.1 = 1.51633 v.sub.1 = 64.15 r.sub.2 = 0.6947 d.sub.2 = 1.2665 r.sub.3 = 1.1738 d.sub.3 = 0.2533 n.sub.2 = 1.74100 v.sub.2 = 52.68 r.sub.4 = -9.5318 d.sub.4 = 0.0507 r.sub.5 = ∞

(aperture diaphragm) d.sub.5 = 0.0507 r.sub.6 = 1.7243 d.sub.6 = 0.5572 n.sub.3 = 1.51633 v.sub.3 = 64.15 r.sub.7 = -0.5220 d.sub.7 = 0.2026 n.sub.4 = 1.80518 v.sub.4 = 25.43 r.sub.8 = -0.9198 d.sub.8 = 0.4008 r.sub.9 = -0.5470 d.sub.9 = 0.2026 n.sub.5 = 1.59270 v.sub.5 = 35.29 r.sub.10 = 1.9496 d.sub.10 = 0.4559 n.sub.6 = 1.80610 v.sub.6 = 40.95 r.sub.11 = -2.4895 h.sub.1 /f.sub.1 = 0.535 h.sub.4 /f.sub.4 = 0.277 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 1.931 f.sub.1 = -1.35 f.sub.2 = 1.425 f.sub.23 = 0.96 f.sub.4 = -1.95 R.sub.2 = -9.5318 R.sub.2 '"'"' = 1.1738 R.sub.3 = 1.7243 R.sub.3 '"'"' = -0.522 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, and v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials.

7. An objective lens system for an endoscope according to claim 2, said first lens component being a negative single lens, said second lens component being a biconvex lens, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.0 image height 1.062 angle of view 119°

______________________________________ r.sub.1 = 4.6673 d.sub.1 = 0.3333 n.sub.1 = 1.883 v.sub.1 = 40.78 r.sub.2 = 0.864 d.sub.2 = 0.5867 r.sub.3 = ∞

d.sub.3 = 0.6667 n.sub.2 = 1.53172 v.sub.2 = 48.9 r.sub.4 = ∞

d.sub.4 = 0.5333 r.sub.5 = 2.6013 d.sub.5 = 0.9533 n.sub.3 = 1.741 v.sub.3 = 52.68 r.sub.6 = -2.6013 d.sub.6 = 0.0667 r.sub.7 = ∞

(aperture diaphragm) d.sub.7 = 0.0667 r.sub.8 = 1.7973 d.sub.8 = 0.70 n.sub.4 = 1.51633 v.sub.4 = 64.15 r.sub.9 = -0.964 d.sub.9 = 0.3333 n.sub.5 = 1.80518 v.sub.5 = 25.43 r.sub.10 = -1.558 d.sub.10 = 0.4667 r.sub.11 = -0.8967 d.sub.11 = 0.3333 n.sub.6 = 1.76182 v.sub.6 = 26.55 r.sub.12 = -1.7693 d.sub.12 = 0.420 r.sub.13 = ∞

d.sub.13 = 0.6667 n.sub.7 = 1.51633 v.sub.7 = 64.15 r.sub.14 = ∞

h.sub.1 /f.sub.1 = 0.71 h.sub.4 /f.sub.4 = 0.18 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 3.967 f.sub.1 = -1.25 f.sub.2 = 1.90 f.sub.23 = 1.28 f.sub.4 = -2.86 R.sub.2 = -2.60 R.sub.2 '"'"' = 2.60 R.sub.3 = 1.80 R.sub.3 '"'"' = -0.96 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, and v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials.

8. An objective lens system for an endoscope according to claim 2, said first lens component being a negative single lens, said second lens component comprising two positive single lenses, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.0 image height 0.92 angle of view 101°

______________________________________ r.sub.1 = 4.4097 d.sub.1 = 0.2877 n.sub.1 = 1.883 v.sub.1 = 40.78 r.sub.2 = 0.7457 d.sub.2 = 0.4816 r.sub.3 = 2.0242 d.sub.3 = 0.8705 n.sub.2 = 1.741 v.sub.2 = 52.68 r.sub.4 = ∞

d.sub.4 = 0.351 r.sub.5 = ∞

d.sub.5 = 0.3049 n.sub.3 = 1.741 v.sub.3 = 52.68 r.sub.6 = -2.0242 d.sub.6 = 0.0575 r.sub.7 = ∞

(aperture diaphragm) d.sub.7 = 0.0575 r.sub.8 = 1.6116 d.sub.8 = 0.5696 n.sub.4 = 1.51633 v.sub.4 = 64.15 r.sub.9 = -1.0213 d.sub.9 = 0.2301 n.sub.5 = 1.80518 v.sub.5 = 25.43 r.sub.10 = -2.1617 d.sub.10 = 0.0575 r.sub.11 = ∞

d.sub.11 = 0.2877 n.sub.6 = 1.53172 v.sub.6 = 48.9 r.sub.12 = ∞

d.sub.12 = 0.3625 r.sub.13 = -0.8009 d.sub.13 = 0.2301 n.sub.7 = 1.72825 v.sub.7 = 28.46 r.sub.14 = -1.3705 d.sub.14 = 0.3855 r.sub.15 = ∞

d.sub.15 = 0.5754 n.sub.8 = 1.51633 v.sub.8 = 64.15 r.sub.16 = ∞

h.sub.1 /f.sub.1 = 0.63 h.sub.4 /f.sub.4 = 0.15 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 4.344 f.sub.1 = -1.06 f.sub.2 = 1.57 f.sub.23 = 1.18 f.sub.4 = -3.19 R.sub. 2 = -2.02 R.sub.2 '"'"' = 2.02 R.sub.3 = 1.61 R.sub.3 '"'"' = -1.02 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, and v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials.

9. An objective lens system for an endoscope according to claim 2, said first lens component being a negative single lens, said second lens component comprising two positive single lenses, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.0 image height 1.063 angle of view 120°

______________________________________ r.sub.1 = 4.0027 d.sub.1 = 0.3336 n.sub.1 = 1.883 v.sub.1 = 40.78 r.sub.2 = 0.8672 d.sub.2 = 0.5337 r.sub.3 = ∞

d.sub.3 = 0.3336 n.sub.2 = 1.53172 v.sub.2 = 48.90 r.sub.4 = ∞

d.sub.4 = 0.2763 r.sub.5 = 3.3266 d.sub.5 = 0.3885 n.sub.3 = 1.741 v.sub.3 = 52.68 r.sub.6 = -5.1676 d.sub.6 = 0.2001 r.sub.7 = -1.3143 d.sub.7 = 0.7465 n.sub.4 = 1.741 v.sub.4 = 52.68 r.sub.8 = -1.3763 d.sub.8 = 0.0667 r.sub.9 = ∞

(aperture diaphragm) d.sub.9 = 0.0667 r.sub.10 = 1.1237 d.sub.10 = 0.9237 n.sub.5 = 1.51633 v.sub.5 = 64.15 r.sub.11 = -0.8226 d.sub.11 = 0.2668 n.sub.6 = 1.80518 v.sub.6 = 25.43 r.sub.12 = -1.4219 d.sub.12 = 0.4003 r.sub.13 = -0.8672 d.sub.13 = 0.3336 n.sub.7 = 1.72825 v.sub.7 = 28.46 r.sub.14 = -1.8779 d.sub.14 = 0.6671 r.sub.15 = ∞

d.sub.15 = 0.3336 n.sub.8 = 1.51633 v.sub.8 = 64.15 r.sub.16 = ∞

h.sub.1 /f.sub.1 = 0.76 h.sub.4 /f.sub.4 = 0.20 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 3.816 f.sub.1 = -1.32 f.sub.2 = 2.72 f.sub.23 = 1.23 f.sub.4 = -2.57 R.sub. 2 = -1.38 R.sub.2 '"'"' = 3.33 R.sub.3 = 1.12 R.sub.3 '"'"' = -0.82 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, and v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials.

10. An objective lens system for an endoscope according to claim 2, said first lens component being a negative single lens, said second lens component being a biconvex lens, said third lens component comprising a cemented lens and a positive lens, said cemented lens comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.0 image height 1.08 angle of view 121°

______________________________________ r.sub.1 = 4.3525 d.sub.1 = 0.339 n.sub.1 = 1.883 v.sub.1 = 40.78 r.sub.2 = 0.7946 d.sub.2 = 0.8793 r.sub.3 = ∞

d.sub.3 = 0.339 n.sub.2 = 1.53172 v.sub.2 = 48.90 r.sub.4 = ∞

d.sub.4 = 0.1627 r.sub.5 = 2.5566 d.sub.5 = 0.4746 n.sub.3 = 1.72825 v.sub.3 = 28.46 r.sub.6 = -2.5566 d.sub.6 = 0.1182 r.sub.7 = ∞

(aperture diaphragm) d.sub.7 = 0.2585 r.sub.8 = 4.6183 d.sub.8 = 0.6813 n.sub.4 = 1.58913 v.sub.4 = 60.97 r.sub.9 = -0.8237 d.sub.9 = 0.2712 n.sub.5 = 1.80518 v.sub.5 = 25.43 r.sub.10 = -1.6936 d.sub.10 = 0.1794 r.sub.11 = 2.4014 d.sub.11 = 0.4746 n.sub.6 = 1,6583 v.sub.6 = 57.33 r.sub.12 = -32.2502 d.sub.12 = 0.2936 r.sub.13 = -1.2908 d.sub.13 = 0.2373 n.sub.7 = 1.80518 v.sub.7 = 25.43 r.sub.14 = -7.7878 d.sub.14 = 0.3276 r.sub.15 = ∞

d.sub.15 = 0.678 n.sub.8 = 1.54869 v.sub.8 = 45.55 r.sub.16 = ∞

h.sub.1 /f.sub.1 = 0.48 h.sub.4 /f.sub.4 = 0.32 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 1.493 f.sub.1 = -1.15 f.sub.2 = 1.83 f.sub.23 = 1.29 f.sub.4 = - 1.95 R.sub.2 = -2.56 R.sub.2 '"'"' = 2.56 R.sub.3 = 4.62 R.sub.3 '"'"' = -0.82 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, and v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respectively materials.

11. An objective lens system for an endoscope according to claim 2, said first lens component being a negative single lens, said second lens component being a biconvex lens, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged between said first lens component and said second lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.0 image height 0.855 angle of view 100°

______________________________________ r.sub.1 = ∞

d.sub.1 = 0.2678 n.sub.1 = 1.883 v.sub.1 = 40.78 r.sub.2 = 0.9363 d.sub.2 = 0.3749 r.sub.3 = ∞

d.sub.3 = 2.6888 n.sub.2 = 1.8061 v.sub.2 = 40.95 r.sub.4 = ∞

(aperture diaphragm) d.sub.4 = 0.1071 r.sub.5 = 2.3091 d.sub.5 = 0.5196 n.sub.3 = 1.64769 v.sub.3 = 33.80 r.sub.6 = -2.3091 d.sub.6 = 0.0536 r.sub.7 = 2.5522 d.sub.7 = 0.7231 n.sub.4 = 1.51633 v.sub.4 = 64.15 r.sub.8 = -1.0198 d.sub.8 = 0.2678 n.sub.5 = 1.84666 v.sub.5 = 23.78 r.sub.9 = -5.4772 d.sub.9 = 0.4713 r.sub.10 = ∞

d.sub.10 = 0.4178 n.sub.6 = 1.51633 v.sub.6 = 64.15 r.sub.11 = -1.5629 d.sub.11 = 0.0536 r.sub.12 = ∞

d.sub.12 = 0.2678 n.sub.7 = 1.53172 v.sub.7 = 48.90 r.sub.13 = ∞

d.sub.13 = 0.2892 r.sub.14 = -1.0311 d.sub.14 = 0.2678 n.sub.8 = 1.883 v.sub.8 = 40.78 r.sub.15 = -1.8843 d.sub.15 = 0.5142 r.sub.16 = ∞

d.sub.16 = 0.5356 n.sub.9 = 1.51633 v.sub.9 = 64.15 r.sub.17 = ∞

h.sub.1 /f.sub.1 = 0.56 h.sub.4 /f.sub.4 = 0.18 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 3.082 f.sub.1 = -1.06 f.sub.2 = 1.87 f.sub.23 = 1.63 f.sub.4 = -3.02 R.sub.2 = -2.3091 R.sub.2 '"'"' = 2.3091 R.sub.3 = 2.5522 R.sub.3 '"'"' = -1.0198 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, and v₁, v₂, . . . respectively represent Abbe'"'"'s number of respective materials.

12. An objective lens system for an endoscope according to claim 2, said first lens component comprising a negative single lens and a biconvex lens, said negative single lens having a image side surface thereof formed as an aspherical one, said second lens component being a biconvex lens, said third lens component comprising a cemented lens and a positive single lens, said cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus single lens having a image side surface thereof formed as an aspherical one, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.0 image height 1.147 angle of view 100°

______________________________________ r.sub.1 = 6.0105 d.sub.1 = 0.3592 n.sub.1 = 1.883 v.sub.1 = 40.78 r.sub.2 = 0.8194 (aspherical) d.sub.2 = 0.7184 r.sub.3 = 9.2577 d.sub.3 = 0.3592 n.sub.2 = 1.53172 v.sub.2 = 48.90 r.sub.4 = -30.2947 d.sub.4 = 0.3879 r.sub.5 = 2.6624 d.sub.5 = 0.5029 n.sub.3 = 1.72825 v.sub.3 = 28.46 r.sub.6 = -3.7679 d.sub.6 = 0.1252 r.sub.7 =∞

(aperture diaphragm) d.sub.7 = 0.274 r.sub.8 = 4.8937 d.sub.8 = 0.6552 n.sub.4 = 1.58913 v.sub.4 = 60.97 r.sub.9 = -0.8923 d.sub.9 = 0.2874 n.sub.5 = 1.80518 v.sub.5 = 25.43 r.sub.10 = -1.5847 d.sub.10 = 0.1901 r.sub.11 = 2.5445 d.sub.11 = 0.5029 n.sub.6 = 1.6583 v.sub.6 = 57.33 r.sub.12 = -34.1731 d.sub.12 = 0.30 r.sub.13 = -1.3263 d.sub.13 = 0.2514 n.sub.7 = 1.80518 v.sub.7 = 25.43 r.sub.14 = -7.5450 (aspherical) d.sub.14 = 0.3471 r.sub.15 = ∞

d.sub.15 = 0.7184 n.sub.8 = 1.54869 v.sub.8 = 45.55 r.sub.16 = ∞

h.sub.1 /f.sub.1 = 0.43 h.sub.4 /f.sub.4 = 0.29 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 1.517 E.sub.2 = 0.51666 ×

10.sup.-1 F.sub.2 = 0.1371 E.sub.14 = 0.17323 F.sub.14 = 0 f.sub.1 = -1.29 f.sub.2 = 2.22 f.sub.23 = 1.37 f.sub.4 = -2.04 R.sub.2 = -3.768 R.sub.2 '"'"'= 2.66 R.sub.3 = 4.89 R.sub.3 '"'"' = -0.89 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials, E₂, F₂ represent the coefficients of said aspherical surface in said first lens component, and E₁₄, F₁₄ represent the coefficients of said aspherical surface in said fourth lens component.

13. An objective lens system for an endoscope according to claim 1, said first lens component comprising a negative single lens and a biconvex lens, said second lens component being a biconvex lens, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component comprising a negative meniscus lens and a biconvex lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.1 image height 1.14 angle of view 138°

______________________________________ r.sub.1 = 5.7266 d.sub.1 = 0.3573 n.sub.1 = 1.883 v.sub.1 = 40.78 r.sub.2 = 0.8615 d.sub.2 = 1.6801 r.sub.3 = 1.7123 d.sub.3 = 0.8102 n.sub.2 = 1.713 v.sub.2 = 53.84 r.sub.4 = -3.5156 d.sub.4 = 0.0039 r.sub.5 = ∞

(aperture diaphragm) d.sub.5 = 0.0659 r.sub.6 = 2.4711 d.sub.6 = 0.6563 n.sub.3 = 1.51633 v.sub.3 = 64.15 r.sub.7 = -0.7133 d.sub.7 = 0.2863 n.sub.4 = 1.80518 v.sub.4 = 25.43 r.sub.8 = -1.2246 d.sub.8 = 0.0636 r.sub.9 = ∞

d.sub.9 = 0.1034 n.sub.5 = 1.53172 v.sub. 5 = 48.90 r.sub.10 = ∞

d.sub.10 = 0.1720 r.sub.11 = -0.9620 d.sub.11 = 0.2147 n.sub.6 = 1.72825 v.sub.6 = 28.46 r.sub.12 = -2.5078 d.sub.12 = 0.0517 r.sub.13 = 7.1019 d.sub.13 = 0.5011 n.sub.7 = 1.51633 v.sub.7 = 64.15 r.sub.14 = -19.3899 d.sub.14 = 0.7158 r.sub.15 = ∞

d.sub.15 = 0.3579 n.sub.8 = 1.51633 v.sub.8 = 64.15 r.sub.16 = ∞

h.sub.1 /f.sub.1 = 0.813 h.sub.4 /f.sub.4 = 0.177 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 4.59 f.sub.1 = -1.189 f.sub.2 = 1.726 f.sub.23 = 1.262 f.sub.4 = -3.075 R.sub.2 = -3.5156 R.sub.2 '"'"' = 1.7123 R.sub.3 = 2.4711 R.sub.3 '"'"' = -0.7133 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, and v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials.

14. An objective lens system for an endoscope according to claim 2, said first lens component being a negative single lens, said second lens component being a biconvex lens, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component comprising a negative meniscus lens and a positive meniscus lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.1 image height 1.2 angle of view 140°

______________________________________ r.sub.1 = 3.1833 d.sub.1 = 0.3782 n.sub.1 = 1.883 v.sub.1 = 40.78 r.sub.2 = 0.8334 d.sub.2 = 1.7146 r.sub.3 = 2.43 d.sub.3 = 0.7182 n.sub.2 = 1.713 v.sub.2 = 53.84 r.sub.4 = -2.2325 d.sub.4 = 0.025 r.sub.5 = ∞

(aperture diaphragm) d.sub.5 = 0.0546 r.sub.6 = 7.1362 d.sub.6 = 0.5463 n.sub.3 = 1.51633 v.sub.3 = 64.15 r.sub.7 = -0.7591 d.sub.7 = 0.2185 n.sub.4 = 1.80518 v.sub.4 = 25.43 r.sub.8 = -1.293 d.sub.8 = 0.0672 r.sub.9 = ∞

d.sub.9 = 0.1092 n.sub.5 = 1.53172 v.sub. 5 = 48.90 r.sub.10 = ∞

d.sub.10 = 0.302 r.sub.11 = -0.888 d.sub.11 = 0.2731 n.sub.6 = 1.72825 v.sub.6 = 28.46 r.sub.12 = -1.1927 d.sub.12 = 0.0546 r.sub.13 = 10.5247 d.sub.13 = 0.5295 n.sub.7 = 1.51633 v.sub.7 = 64.15 r.sub.14 = 117.0536 d.sub.14 = 0.7564 r.sub.15 = ∞

d.sub.15 = 0.3782 n.sub.8 = 1.51633 v.sub.8 = 64.15 r.sub.16 = ∞

h.sub.1 /f.sub.1 = 0.801 h.sub.4 /f.sub.4 = 0.0488 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 16.41 f.sub.1 = -1.383 f.sub.2 = 1.744 f.sub.23 = 1.335 f.sub.4 = -12.545 R.sub.2 = -2.2325 R.sub.2 '"'"'= 2.43 R.sub.3 = 7.1362 R.sub.3 '"'"' = -0.7591 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, and v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials.

15. An objective lens system for an endoscope according to claim 2, said first lens component being an aspherical lens component.

16. An objective lens system for an endoscope according to claim 15, said first lens component being a negative single lens having an object side surface thereof formed as an aspherical one, said second lens component being a biconvex lens, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.438 image height 1.1036 angle of view 101°

______________________________________ r.sub.1 = ∞

(aspherical) d.sub.1 = 0.2770 n.sub.1 = 1.51633 v.sub.1 = 64.15 r.sub.2 = 0.7047 d.sub.2 = 1.3918 r.sub.3 = 1.8404 d.sub.3 = 0.2770 n.sub.2 = 1.74100 v.sub.2 = 52.68 r.sub.4 = -6.2624 d.sub.4 = 0.0554 r.sub.5 = ∞

(aperture diaphragm) d.sub.5 = 0.0554 r.sub.6 = 3.4891 d.sub.6 = 0.6094 n.sub.3 = 1.62041 v.sub.3 = 60.27 r.sub.7 = -0.5540 d.sub.7 = 0.2216 n.sub.4 = 1.80518 v.sub.4 = 25.43 r.sub.8 = -1.1104 d.sub.8 = 0.9041 r.sub.9 = -0.6186 d.sub.9 = 0.2770 n.sub.5 = 1.72825 v.sub.5 = 28.46 r.sub.10 = -1.0830 h.sub.1 /f.sub.1 = 0.565 h.sub.4 /f.sub.4 = 0.221 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 2.557 E.sub.1 = 0.46954 ×

10.sup.-1 f.sub.1 = -1.57 f.sub.2 = 1.948 f.sub.23 = 1.14 f.sub.4 = -2.65 R.sub.2 = -6.2624 R.sub.2 '"'"' = 1.8404 R.sub.3 = 3.4891 R.sub.3 '"'"' = -0.554 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between the respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials, and E₁ represents the coefficient of said aspherical surface.

17. An objective lens system for an endoscope according to claim 15, said first lens component being a negative single lens having an object side surface thereof formed as an aspherical one, said second lens component being a cemented lens component consisting of a positive lens and a negative lens, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F / 3.365 image height 1.0969 angle of view 98°

______________________________________ r.sub.1 = ∞

(aspherical) d.sub.1 = 0.2753 n.sub.1 = 1.51633 v.sub.1 = 64.15 r.sub.2 = 0.7513 d.sub.2 = 1.4662 r.sub.3 = 2.3609 d.sub.3 = 0.5507 n.sub.2 = 1.59270 v.sub.2 = 35.29 r.sub.4 = -1.0953 d.sub.4 = 0.2203 n.sub.3 = 1.83400 v.sub.3 = 37.16 r.sub.5 = -2.7689 d.sub.5 = 0.0551 r.sub.6 = ∞

(aperture diaphragm) d.sub.6 = 0.0551 r.sub.7 = 2.3940 d.sub.7 = 0.6057 n.sub.4 = 1.62041 v.sub.4 = 60.27 r.sub.8 = -0.5884 d.sub.8 = 0.2203 n.sub.5 = 1.80518 v.sub.5 = 25.43 r.sub.9 = - 1.1177 d.sub.9 = 0.8941 r.sub.10 = -0.6526 d.sub.10 = 0.2753 n.sub.6 = 1.84666 v.sub.6 = 23.88 r.sub.11 = -0.9566 h.sub.1 /f.sub.1 = 0.637 h.sub.4 /f.sub.4 = 0.135 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 4.72 E.sub.1 = 0.58567 ×

10.sup.-1 f.sub.1 = -1.46 f.sub.2 = 3.095 f.sub.23 = 1.27 f.sub.4 = -4.15 R.sub.2 = -2.7689 r.sub.2 '"'"' = 2.3609 R.sub.3 = 2.394 R.sub.3 '"'"' = -0.5884 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials, and E₁ represents the coefficient of said aspherical surface.

18. An objective lens system for an endoscope according to claim 15, said first lens component being a negative single lens having an object side surface thereof formed as an aspherical one, said second lens component being a cemented lens component consisting of a positive lens and a negative lens, said third lens component being a cemented lens component comprising a negative lens and a positive lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.295 image height 1.1141 angle of view 99°

______________________________________ r.sub.1 = ∞

(aspherical) d.sub.1 = 0.2796 n.sub.1 = 1.51633 v.sub.1 = 64.15 r.sub.2 = 0.7952 d.sub.2 = 1.4787 r.sub.3 = 5.3878 d.sub.3 = 0.5593 n.sub.2 = 1.59270 v.sub.2 = 35.29 r.sub.4 = -0.7414 d.sub.4 = 0.2237 n.sub.3 = 1.83400 v.sub.3 = 37.16 r.sub.5 = -1.9280 d.sub.5 = 0.0559 r.sub.6 = ∞

(aperture diaphragm) d.sub.6 = 0.0559 r.sub.7 = 1.5169 d.sub.7 = 0.2237 n.sub.4 = 1.80518 v.sub.4 = 25.43 r.sub.8 = 0.6123 d.sub.8 = 0.6152 n.sub.5 = 1.56883 v.sub.5 = 56.34 r.sub.9 = -1.0448 d.sub. 9 = 0.8849 r.sub.10 = -0.7375 d.sub.10 = 0.2796 n.sub.6 = 1.84666 v.sub.6 = 23.88 r.sub.11 = -1.0612 h.sub.1 /f.sub.1 = 0.631 h.sub.4 /f.sub.4 = 0.12 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 5.26 E.sub.1 = 0.54347 ×

10.sup.-1 f.sub.1 = -1.54 f.sub.2 = 4.471 f.sub.23 = 1.27 f.sub.4 = -4.73 R.sub.2 = -1.928 R.sub.2 '"'"'= 5.3878 R.sub.3 = 1.5169 R.sub.3 '"'"' = 0.6123 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials, and E₁ represents the coefficient of said aspherical surface.

19. An objective lens system for an endoscope comprising, in the order from the object side, a first lens component having a negative refracting power, a second lens component having a positive refracting power, a third lens component having a positive refracting power, a fourth lens component involving a meniscus lens having its concave surface facing the object side, and an aperture diaphragm arranged between the outermost surface of the second lens component toward the object and the outermost surface of the third lens component toward the image, said first lens component being an aspherical lens component having at least one aspherical surface the shape of which is that the object side surface of the lens component involves such a portion that the curvature of object side surface becomes progressively stronger toward the edge of the surface and the image side surface of the lens component involves such a portion that the curvature of image side surface becomes progressively weaker toward the edge of the surface, and said object lens system for an endoscope satisfying the following condition (1):

space="preserve" listing-type="equation">|h.sub.1 /f.sub.1 |>

1.15|h.sub.4 /f.sub.4 | (1)

where, h₁ and h₄ represent the mean values of the heights of the principal ray at respective surfaces of said first lens component and said fourth lens component, f₁ and f₄ represent the focal lengths of the first lens component and the fourth lens component, respectively.

20. An objective lens system for an endoscope according to claim 19, further satisfying the following conditions (2), (3), and (4):

space="preserve" listing-type="equation">f.sub.2 <

3.5 f (2)

space="preserve" listing-type="equation">|f.sub.4 |<

6 tm (3)

space="preserve" listing-type="equation">-R.sub.2 ≦

15 f (4)

where f₂ represents the focal length of the second lens component, f represents the focal length of the objective lens system, R₂ represents the radius of curvature of the image side surface of said second lens component.

21. An objective lens system for an endoscope according to claim 20, said third lens component being a cemented lens component, and further satisfying the following conditions (5) through (8):

space="preserve" listing-type="equation">|f.sub.1 |<

1.7 f (5)

space="preserve" listing-type="equation">|f.sub.23 |<

1.7 f (6)

space="preserve" listing-type="equation">R.sub.2 '"'"'>

0 (7)

space="preserve" listing-type="equation">R.sub.3 <

5 f (8)

space="preserve" listing-type="equation">|R.sub.3 '"'"'|<

3 f (9)

where f₂₃ represents the composite focal length of said second lens component and said third lens component, R₂ '"'"' represents the radius of curvature of said outermost surface of said second lens component towards the object, R₃ represents the radius of curvature of the outermost surface of the third lens component towards the object, R₃ '"'"' represents the radius of curvature of the cemented surface of said third lens component.

22. An objective lens system for an endoscope according to claim 21, said first lens component being a negative single lens having an object side surface thereof formed as an aspherical one, said second lens component being a biconvex lens, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.438 image height 1.1036 angle of view 101°

______________________________________ r.sub.1 = ∞

(aspherical) d.sub.1 = 0.2770 n.sub.1 = 1.51633 v.sub.1 = 64.15 r.sub.2 = 0.7047 d.sub.2 = 1.3918 r.sub.3 = 1.8404 d.sub.3 = 0.22770 n.sub.2 = 1.74100 v.sub.2 = 52.68 r.sub.4 = -6.2624 d.sub.4 = 0.0554 r.sub.5 =∞

(aperture diaphragm) d.sub.5 = 0.554 r.sub.6 = 3.4891 d.sub.6 = 0.6094 n.sub.3 = 1.62041 v.sub.3 = 60.27 r.sub.7 = -0.5540 d.sub.7 = 0.2216 n.sub.4 = 1.80518 v.sub.4 = 25.43 r.sub.8 = -1.1104 d.sub.8 = 0.9041 r.sub.9 = -0.6186 d.sub.9 = 0.2770 n.sub.5 = 1.72825 v.sub.5 = 28.46 r.sub.10 = -1.0830 h.sub.1 /f.sub.1 = 0.565 h.sub.4 /f.sub.4 = 0.221 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 2.557 E.sub.1 = 0.46954 ×

10.sup.-1 f.sub.1 = -1.57 f.sub.2 = 1.948 f.sub.23 = 1.14 f.sub.4 = -2.65 R.sub.2 = -6.2624 R.sub.2 '"'"' = 1.8404 R.sub.3 = 3.4891 R.sub.3 '"'"' = -0.554 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials, and E₁ represents the coefficient of said aspherical surface.

23. An objective lens system for an endoscope according to claim 21, said first lens component being a negative single lens having an object side surface thereof formed as an aspherical one, said second lens component being a cemented lens component consisting of a positive lens and a negative lens, said third lens component being a cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.365 image height 1.0969 angle of view 98°

______________________________________ r.sub.1 = ∞

(aspherical) d.sub.1 = 0.2753 n.sub..sub.1 = 1.51633 v.sub.1 = 64.15 r.sub.2 = 0.7513 d.sub.2 = 1.4662 r.sub.3 = 2.3609 d.sub.3 = 0.5507 n.sub.2 = 1.59270 v.sub.1 = 35.29 r.sub.4 = -1.0953 d.sub.4 = 0.2203 n.sub..sub.3 = 1.83400 v.sub.3 = 37.16 r.sub.5 = -2.7689 d.sub.5 = 0.0551 r.sub.6 = ∞

(aperture diaphragm) d.sub.6 = 0.0551 r.sub.7 = 2.3940 d.sub.7 = 0.6057 n.sub.4 = 1.62041 v.sub.4 = 60.27 r.sub.8 = -0.5884 d.sub.8 = 0.2203 n.sub.5 = 1.80518 v.sub.5 = 25.43 r.sub.9 = - 1.1177 d.sub.9 = 0.8941 r.sub.10 = -0.6526 d.sub.10 = 0.2753 n.sub.6 = 1.84666 v.sub.6 = 23.88 r.sub.11 = -0.9566 h.sub.1 /f.sub.1 = 0.637 h.sub.4 /f.sub.4 = 0.135 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 4.72 E.sub.1 = 0.58567 ×

10.sup.-1 f.sub.1 = -1.46 f.sub.2 = 3.095 f.sub.23 = 1.27 f.sub.4 = -4.15 R.sub.2 32 -2.7689 R.sub.2 '"'"' = 2.3609 R.sub.3 = 2.394 R.sub.3 '"'"' = -0.5884 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials, and E₁ represents the coefficient of said aspherical surface.

24. An objective lens system for an endoscope according to claim 21, said first lens component being a negative single lens having an object side surface thereof formed as an aspherical one, said second lens component being a cemented lens component consisting of a positive lens and a negative lens, said third lens component being a cemented lens component comprising a negative lense and a positive lens, and said fourth lens component being a negative meniscus lens, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.295 image height 1.1141 angle of view 99°

______________________________________ r.sub.1 = ∞

(aspherical) d.sub.1 = 0.2796 n.sub.1 = 1.51633 v.sub.1 = 64.15 r.sub.2 = 0.7952 d.sub.2 = 1.4787 r.sub.3 = 5.3878 d.sub.3 = 0.5593 n.sub.2 = 1.59270 v.sub.2 = 35.29 r.sub.4 = -0.7414 d.sub.4 = 0.2237 n.sub.3 = 1.83400 v.sub.3 = 37.16 r.sub.5 = -1.9280 d.sub.5 = 0.0559 r.sub.6 = ∞

(aperture diaphragm) d.sub.6 = 0.0559 r.sub.7 = 1.5169 d.sub.7 = 0.2237 n.sub.4 = 1.80518 v.sub.4 = 25.43 r.sub.8 = 0.6123 d.sub.8 = 0.6152 n.sub.5 = 1.56883 v.sub.5 = 56.34 r.sub.9 = -1.0448 d.sub. 9 = 0.8849 r.sub.10 = -0.7375 d.sub.10 = 0.2796 n.sub.6 = 1.84666 v.sub.6 = 23.88 r.sub.11 = -1.0612 h.sub.1 /f.sub.1 = 0.631 h.sub.4 /f.sub.4 = 0.12 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 5.26 E.sub.1 = 0.54347 ×

10.sup.-1 f.sub.1 = -1.54 f.sub.2 = 4.471 f.sub.23 = 1.27 f.sub.4 = -4.73 R.sub.2 = -1.928 R.sub.2 '"'"'= 5.3878 R.sub.3 = 1.5169 R.sub.3 '"'"' = 0.6123 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials, and E₁ represents the coefficient of said aspherical surface.

25. An objective lens system for an endoscope according to claim 19, said fourth lens component being an aspherical lens component having at least one aspherical surface the shape of which is that the object side surface of the lens component involves such a portion that the absolute value of the curvature of object side surface becomes progressively larger toward the edge of the surface and the image side surface of the lens component involves such a portion that the absolute value of the curvature of image side surface becomes progressively smaller toward the edge of the surface.

26. An objective lens system for an endoscope according to claim 25, further satisfying the following conditions (2), (3), and (4):

space="preserve" listing-type="equation">f.sub.2 <

3.5 f (2)

space="preserve" listing-type="equation">|f.sub.4 |<

6 f (3)

space="preserve" listing-type="equation">-R.sub.2 ≦

15 f (4)

where f₂ represents the focal length of the second lens component, f represents the focal length of the objective lens system, R₂ represents the radius of curvature of the image side surface of said second lens component.

27. An objective lens system for an endoscope according to claim 26, said third lens component being a cemented lens component, and further satisfying the following conditions (5) through (8):

space="preserve" listing-type="equation">|f.sub.1 |<

1.7 f (5)

space="preserve" listing-type="equation">|f.sub.23 |<

1.7 f (6)

space="preserve" listing-type="equation">R.sub.2 '"'"'>

0 (7)

space="preserve" listing-type="equation">R.sub.3 <

5 f (8)

space="preserve" listing-type="equation">|R.sub.3 '"'"'|<

3 f (9)

where f₂₃ represents the composite focal length of said second lens component and said third lens component, R₂ '"'"' represents the radius of curvature of said outermost surface of said second lens component towards the object, R₃ represents the radius of curvature of the outermost surface of the third lens component towards the object, R₃ '"'"' represents the radius of curvature of the cemented surface of said third lens component.

28. An objective lens system for an endoscope according to claim 27, said first lens component comprising a negative single lens and a biconvex lens, said negative single lens having a image side surface thereof formed as an aspherical one, said second lens component being a biconvex lens, said third lens component comprising a cemented lens and a positive single lens, said cemented lens component comprising a positive lens and a negative lens, and said fourth lens component being a negative meniscus single lens having a image side surface thereof formed as an aspherical one, wherein said aperture diaphragm is arranged between said second lens component and said third lens component, and said objective lens system for an endoscope has the following numerical data:

space="preserve" listing-type="tabular">______________________________________ f = 1.00 F/3.0 image height 1.147 angle of view 100°

______________________________________ r.sub.1 = 6.0105 d.sub.1 = 0.3592 n.sub.1 = 1.883 v.sub.1 = 40.78 r.sub.2 = 0.8194 (aspherical) d.sub.2 = 0.7184 r.sub.3 = 9.2577 d.sub.3 = 0.3592 n.sub.2 = 1.53172 v.sub.2 = 48.90 r.sub.4 = -30.2947 d.sub.4 = 0.3879 r.sub.5 = 2.6624 d.sub.5 = 0.5029 n.sub.3 = 1.72825 v.sub.3 = 28.46 r.sub.6 = -3.7679 d.sub.6 = 0.1252 r.sub.7 =∞

(aperture diaphragm) d.sub.7 = 0.274 r.sub.8 = 4.8937 d.sub.8 = 0.6552 n.sub.4 = 1.58913 v.sub.4 = 60.97 r.sub.9 = -0.8923 d.sub.9 = 0.2874 n.sub.5 = 1.80518 v.sub.5 = 25.43 r.sub.10 = -1.5847 d.sub.10 = 0.1901 r.sub.11 = 2.5445 d.sub.11 = 0.5029 n.sub.6 = 1.6583 v.sub.6 = 57.33 r.sub.12 = -34.1731 d.sub.12 = 0.30 r.sub.13 = -1.3263 d.sub.13 = 0.2514 n.sub.7 = 1.80518 v.sub.7 = 25.43 r.sub.14 = -7.5450 (aspherical) d.sub.14 = 0.3471 r.sub.15 = ∞

d.sub.15 = 0.7184 n.sub.8 = 1.54869 v.sub.8 = 45.55 r.sub.16 = ∞

h.sub.1 /f.sub.1 = 0.43 h.sub.4 /f.sub.4 = 0.29 (h.sub.1 /f.sub.1)/(h.sub.4 /f.sub.4) = 1.517 E.sub.2 = 0.51666 ×

10.sup.-1 F.sub.2 = 0.1371 E.sub.14 = 0.17323 F.sub.14 = 0 f.sub.1 = -1.29 f.sub.2 = 2.22 f.sub.23 = 1.37 f.sub.4 = -2.04 R.sub.2 = -3.768 R.sub.2 '"'"'= 2.66 R.sub.3 = 4.89 R.sub.3 '"'"' = -0.89 ______________________________________

where r₁, r₂, . . . respectively represent the radii of curvature of respective surfaces, d₁, d₂, . . . respectively represent the spaces between respective surfaces, n₁, n₂, . . . respectively represent the refractive indices of respective materials, v₁, v₂, . . . respectively represent Abbe'"'"'s numbers of respective materials, E₂, F₂ represent the coefficients of said aspherical surface in said first lens component, and E₁₄, F₁₄ represent the coefficients of said aspherical surface in said fourth lens component.