Objective lens system for endoscopes

• US 4,493,537 A
• Filed: 11/04/1982
• Issued: 01/15/1985
• Est. Priority Date: 11/10/1981
• Status: Expired due to Fees

• Current Assignee: Olympus Optical Corporation Limited (Olympus Corporation)
• Original Assignee: Olympus Optical Company Ltd. (Olympus Corporation)
• Inventors: Nakahashi, Kenichi
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/439,293
• Time in Patent Office: 803 Days
• Field of Search: 350/469, 350/450
• US Class Current: 359/783
• CPC Class Codes: G02B 13/04 Reversed telephoto objectives
• CPC Class Codes: G02B 9/34 having four components only

Abstract

An objective lens system for endoscopes comprising a first negative meniscus lens component, a second positive meniscus lens component, a third biconvex lens component and a fourth positive cemented doublet component consisting of a positive lens element and a negative lens element, said lens system having a super-wide angle and favorably corrected aberrations, especially spherical aberration and lateral chromatic aberration.

Claims

1. An objective lens system for endoscopes comprising a first negative meniscus lens component having a concave surface on the image side, an aperture stop, a second positive meniscus lens component, a third biconvex lens component and a fourth positive cemented doublet component consisting of a positive lens element and a negative lens element, said lens system being so designed as to satisfy the following conditions:

##EQU2## wherein the reference symbol f represents total focal length of the entire lens system as a whole, the reference symbol f₂₃₄ designates total focal length of said second, third and fourth lens components as a whole, the reference symbols r₂ , r₅ and r₇ denote radii of curvature on the image side surface of said first lens component, image side surface of said second lens component and image side surface of said third lens component, the reference symbols n₁ through n₅ represent refractive indices of the respective lens elements and the reference symbols ν

₁, ν

₂ and ν

₃ designate Abbe'"'"'s numbers of said first, second and third lens components respectively.

2. An objective lens system for endoscopes according to claim 1 wherein said aperture stop is arranged in the vicinity of the object side focal point of said rear lens group consisting of said second, third and fourth lens components.

3. An objective lens system for endoscopes according to claim 1 having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 40.340 d.sub.1 = 0.509 n.sub.1 = 1.58913 ν

.sub.1 = 60.97 r.sub.2 = 0.844 d.sub.2 = 1.253 r.sub.3 = ∞

d.sub.3 = 0.372 r.sub.4 = -35.462 d.sub.4 = 1.067 n.sub.2 = 1.69680 ν

.sub.2 = 55.52 r.sub.5 = -2.318 d.sub.5 = 0.124 r.sub.6 = 9.484 d.sub.6 = 1.129 n.sub.3 =1.51728 ν

.sub.3 = 69.56 r.sub.7 = -2.955 d.sub.7 = 0.124 r.sub.8 = 2.782 d.sub.8 = 1.948 n.sub.4 = 1.61800 ν

.sub.4 = 63.38 r.sub.9 = -1.608 d.sub.9 = 0.434 n.sub.5 = 1.84666 ν

.sub.5 = 23.90 r.sub.10 = - 49.305 f = 1.0, 1 = 15.0, S = 0.81 IH = 0.881 2ω

= 115.84°

, Σ

P = -0.014 NA = 0.0129, f.sub.234 /f = 1.614 ##STR16## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, reference symbols IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum and the reference symbol NA represents numerical aperture.

4. An objective lens system for endoscopes according to claim 1 having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 20.6504 d.sub.1 = 0.5001 n.sub.1 = 1.58913 ν

.sub.1 = 60.97 r.sub.2 = 0.8479 d.sub.2 = 1.2476 r.sub.3 = ∞

d.sub.3 = 0.3770 r.sub.4 = -63.1598 d.sub.4 = 1.0635 n.sub.2 = 1.69680 ν

.sub.2 = 55.52 r.sub.5 = -2.4379 d.sub.5 = 0.1251 r.sub.6 = 7.2310 d.sub.6 = 1.1253 n.sub.3 = 1.51728 ν

.sub.3 = 69.56 r.sub.7 = -3.0381 d.sub.7 = 0.1255 r.sub.8 = 2.6453 d.sub.8 = 1.8743 n.sub.4 = 1.61800 ν

.sub.4 = 63.38 r.sub.9 = -1.6289 d.sub.9 = 0.4375 n.sub.5 = 1.84666 ν

.sub.5 = 23.90 r.sub.10 = -812.0951 f = 1.0, 1 = 15.0, S = 0.773 IH = 0.881, 2ω

= 115.57°

, Σ

P = 0 NA = 0.0129, f.sub.234 /f = 1.587 ##STR17## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference symbol IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum and the reference symbol NA represents numerical aperture.

5. An objective lens system for endoscopes according to claim 1 having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 21.3790 d.sub.1 = 0.5062 n.sub.1 = 1.58913 ν

.sub.1 = 60.97 r.sub.2 = 0.8417 d.sub.2 = 1.2469 r.sub.3 = ∞

d.sub.3 = 0.3704 r.sub.4 = -35.9354 d.sub.4 = 1.0617 n.sub.2 = 1.69680 ν

.sub.2 = 55.52 r.sub.5 = -2.2956 d.sub.5 = 0.1246 r.sub.6 = 8.7810 d.sub.6 = 1.1235 n.sub.3 = 1.51728 ν

.sub.3 = 69.56 r.sub.7 = -3.0240 d.sub.7 = 0.1235 r.sub.8 = 2.6730 d.sub.8 = 1.8765 n.sub.4 = 1.61800 ν

.sub.4 = 63.38 r.sub.9 = -1.6290 d.sub.9 = 0.4321 n.sub.5 = 1.84666 ν

.sub.5 = 23.90 r.sub.10 = -206.3722 f = 1.0, 1 = 15.0, S = 0.794 IH = 0.881, 2ω

= 114.86°

, Σ

P = -0.006 NA = 0.0129, f.sub.234 /f = 1.589 ##STR18## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference symbol IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum and the reference symbol NA represents numerical aperture.

6. An objective lens system for endoscopes according to claim 1 having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 17.6741 d.sub.1 = 0.4938 n.sub.1 = 1.58913 ν

.sub.1 = 60.97 r.sub.2 = 0.8373 d.sub.2 = 0.9877 r.sub.3 = ∞

d.sub.3 = 0.6173 r.sub.4 = -36.3478 d.sub.4 = 1.0494 n.sub.2 = 1.69680 ν

.sub.2 = 55.52 r.sub.5 = -2.4411 d.sub.5 = 0.1246 r.sub.6 = 6.5303 d.sub.6 = 1.0864 n.sub.3 = 1.48749 ν

.sub.3 = 70.15 r.sub.7 = -2.8037 d.sub.7 = 0.1235 r.sub.8 = 2.5290 d.sub.8 = 1.7284 n.sub.4 = 1.61800 ν

.sub.4 = 63.38 r.sub.9 = -1.5909 d.sub.9 = 0.4321 n.sub.5 = 1.84666 ν

.sub.5 = 23.90 r.sub.10 = 89.7642 f = 1.0, 1 = 15.0, S = 0.863 IH = 0.881, 2ω

= 115.53°

, Σ

P = 0 NA = 0.0129, f.sub.234 /f = 1.574 ##STR19## ______________________________________

wherein reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference symbol IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum and the reference symbol NA represents numerical aperture.

7. An objective lens system for endoscopes according to claim 1 having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 20.3968 d.sub.1 = 0.4938 n.sub.1 = 1.58913 ν

.sub.1 = 60.97 r.sub.2 = 0.8374 d.sub.2 = 0.9877 r.sub.3 = ∞

d.sub.3 = 0.6173 r.sub.4 = -62.3951 d.sub.4 = 1.0494 n.sub.2 = 1.6968 ν

.sub.2 = 55.52 r.sub.5 = -2.4077 d.sub.5 = 0.1235 r.sub.6 = 7.1414 d.sub.6 = 1.1110 n.sub.3 = 1.51728 ν

.sub.3 = 69.56 r.sub.7 = -3.0005 d.sub.7 = 0.1236 r.sub.8 = 2.6126 d.sub.8 = 1.7284 n.sub.4 = 1.61800 ν

.sub.4 = 63.38 r.sub.9 = -1.6088 d.sub.9 = 0.4321 n.sub.5 = 1.84666 ν

.sub.5 = 23.90 r.sub.10 = - 796.822 f = 1, 1 = 15.0, S = 0.863 IH = 0.881, 2ω

= 115.71°

, Σ

P = 0 NA = 0.013, f.sub.234 /f = 1.584 ##STR20## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference symbol IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum and the reference symbol NA represents numerical aperture.

8. An objective lens system for endoscopes according to claim 1 having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sup.1 = 46.5568 d.sub.1 = 0.5043 n.sub.1 = 1.58913 ν

.sub.1 = 60.97 r.sub.2 = 0.8358 d.sub.2 = 1.2423 r.sub.3 = ∞

d.sub.3 = 0.3690 r.sub.4 = -39.4208 d.sub.4 = 1.0578 n.sub.2 = 1.6968 ν

.sub.2 = 55.52 r.sub.5 = -2.2932 d.sub.5 = 0.1230 r.sub.6 = 8.9076 d.sub.6 = 1.1193 n.sub.3 = 1.5728 ν

.sub.3 = 69.56 r.sub.7 = -2.9702 d.sub.7 = 0.1230 r.sub.8 = 2.7349 d.sub.8 = 1.8696 n.sub.4 = 1.61800 ν

.sub.4 = 63.38 r.sub.9 = -1.5664 d.sub.9 = 0.4305 n.sub.5 = 1.84666 ν

.sub.5 = 23.90 r.sub.10 = -363.0739 f = 1.0, l = 15.0, S = 0.838 IH = 0.881, 2ω

= 115.646°

, Σ

P = -0.022 NA = 0.0129, f.sub.234 /f = 1.53 ##STR21## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference sybmol IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum and the reference symbol NA represents numerical aperture.

9. An objective lens system for endoscopes according to claim 1 having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 75.582 d.sub.1 = 0.523 n.sub.1 = 1.58913 ν

.sub.1 = 60.97 r.sub.2 = 0.872 d.sub.2 = 1.264 r.sub.3 = ∞

d.sub.3 = 0.376 r.sub.4 = -31.949 d.sub.4 = 1.076 n.sub.2 = 1.69680 ν

.sub.2 = 55.52 r.sub.5 = -2.309 d.sub.5 = 0.125 r.sub.6 = 10.102 d.sub.6 = 1.139 n.sub.3 = 1.51728 ν

.sub.3 = 69.56 r.sub.7 = -2.963 d.sub.7 = 0.125 r.sub.8 = 2.737 d.sub.8 = 1.965 n.sub.4 = 1.6180 ν

.sub.4 = 63.38 r.sub.9 = -1.602 d.sub.9 = 0.439 n.sub.5 = 1.84666 ν

.sub.5 = 23.90 r.sub.10 = - 72.703 f = 1.0, l = 15.0, S = 0.78 IH = 0.888. 2ω

= 117.85°

, Σ

P = -0.009 NA = 0.0132, f.sub.234 /f = 1.563 ##STR22## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference symbol IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum and the reference symbol NA represents numerical aperture.

10. An objective lens system for endoscopes according to claim 1 having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 76.346 d.sub.1 = 0.5277 n.sub.1 = 1.58913 ν

.sub.1 = 60.97 r.sub.2 = 0.880 d.sub.2 = 1.2771 r.sub.3 = ∞

d.sub.3 = 0.38 r.sub.4 = -31.030 d.sub.4 = 1.0872 n.sub.2 = 1.670 ν

.sub.2 = 57.33 r.sub.5 = -2.242 d.sub.5 = 0.1010 r.sub.6 = 10.204 d.sub.6 = 1.1505 n.sub.3 = 1.51728 ν

.sub.3 = 69.56 r.sub.7 = -2.993 d.sub.7 = 0.1010 r.sub.8 = 2.764 d.sub.8 = 2.0202 n.sub.4 = 1.618 ν

.sub.4 = 63.38 r.sub.9 = -1.618 d.sub.9 = 0.4433 n.sub.5 = 1.84666 ν

.sub.5 = 23.90 r.sub.10 = -73.4376 f = 1.0, l = 15.0, S = 0.762 IH = 0.899, 2ω

= 120.19°

, Σ

P = -0.006 NA = 0.013, f.sub.234 /f = 1.612 ##STR23## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference symbol IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum and the reference symbol NA represents numerical aperture.

11. An objective lens system for endoscopes according to claim 1 having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 75.582 d.sub.1 = 0.523 n.sub.1 = 1.58913 ν

.sub.1 = 60.97 r.sub.2 = 0.872 d.sub.2 = 1.264 r.sub.3 = ∞

d.sub.3 = 0.376 r.sub.4 = -31.949 d.sub.4 = 1.076 n.sub.2 = 1.6968 ν

.sub.2 = 55.52 r.sub.5 = -2.309 d.sub.5 = 0.125 r.sub.6 = 10.102 d.sub.6 = 1.139 n.sub.3 = 1.51728 ν

.sub.3 = 69.56 r.sub.7 = -2.963 d.sub.7 = 0.125 r.sub.8 = 3.074 d.sub.8 = 1.965 n.sub.4 = 1.69249 ν

.sub.4 = 58.56 r.sub.9 = -1.602 d.sub.9 = 0.439 n.sub.5 = 1.92286 ν

.sub.5 = 21.29 r.sub.10 = -36.333 f = 1.0, l = 15.0, S = 0.853 IH = 0.89, 2ω

= 117.6°

, Σ

P = -0.005 NA = 0.0129, f.sub.234 /f = 1.583 ##STR24## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference symbol IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum and the reference symbol NA represents numerical aperture.

12. An objective lens system for endoscopes according to claim 1 having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 39.261 d.sub.1 = 0.45 n.sub.1 = 1.58913 ν

.sub.1 = 60.97 r.sub.2 = 0.834 d.sub.2 = 1.28 r.sub.3 = ∞

d.sub.3 = 0.38 r.sub.4 = -33.554 d.sub.4 = 1.05 n.sub.2 = 1.6968 ν

.sub.2 = 55.52 r.sub.5 = -2.325 d.sub.5 = 0.1 r.sub.6 = 10.771 d.sub.6 = 1.06 n.sub.3 = 1.51728 ν

.sub.3 = 69.56 r.sub.7 = -2.962 d.sub.7 = 0.1 r.sub.8 = 2.907 d.sub.8 = 1.85 n.sub.4 = 1.6180 ν

.sub.4 = 63.38 r.sub.9 = -1.659 d.sub.9 = 0.44 n.sub.5 = 1.84666 ν

.sub.5 = 23.90 r.sub.10 = - 22.0281 f = 1.0, l = 15.0, S = 0.986 IH = 0.9, 2ω

= 118°

, Σ

P = -0.018 NA = 0.0133, f.sub.234 /f = 1.651 ##STR25## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference symbol IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum and the reference symbol NA represents numerical aperture.

13. An objective lens system for endoscopes according to claim 1 having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 53.309 d.sub.1 = 0.444 n.sub.1 = 1.58913 ν

.sub.1 = 60.97 r.sub.2 = 0.833 d.sub.2 = 1.262 r.sub.3 = ∞

d.sub.3 = 0.375 r.sub.4 = -31.892 d.sub.4 = 1.036 n.sub.2 = 1.6968 ν

.sub.2 = 55.52 r.sub.5 = -2.305 d.sub.5 = 0.099 r.sub.6 = 10.489 d.sub.6 = 1.045 n.sub.3 = 1.51728 ν

.sub.3 = 69.56 r.sub.7 = -2.934 d.sub.7 = 0.099 r.sub.8 = 2.852 d.sub.8 = 1.825 n.sub.4 = 1.6180 ν

.sub.4 = 63.38 r.sub.9 = -1.638 d.sub.9 = 0.434 n.sub.5 = 1.84666 ν

.sub.5 = 23.90 r.sub.10 = -22.031 f = 1.0, 1 = 15.0, S = 0.974 IH = 0.89, 2ω

= 118.0°

, Σ

P = -0.016 NA = 0.0129, f.sub.234 /f = 1.630 ##STR26## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference symbol IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum and the reference symbol NA represents numerical aperture.

14. An objective lens system for endoscopes according to claim 1 having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 87.350 d.sub.1 = 0.523 n.sub.1 = 1.58913 ν

.sub.1 = 60.97 r.sub.2 = 0.871 d.sub.2 = 1.264 r.sub.3 = ∞

d.sub.3 = 0.376 r.sub.4 = -34.593 d.sub.4 = 1.076 n.sub.2 = 1.6968 ν

.sub.2 = 55.52 r.sub.5 = -2.281 d.sub.5 = 0.125 r.sub.6 = 11.081 d.sub.6 = 1.080 n.sub.3 = 1.48749 ν

.sub.3 = 70.15 r.sub.7 = -2.839 d.sub.7 = 0.120 r.sub.8 = 2.693 d.sub.8 = 1.965 n.sub.4 = 1.6180 ν

.sub.4 = 63.38 r.sub.9 = -1.604 d.sub.9 = 0.439 n.sub.5 = 1.84666 ν

.sub.5 = 23.90 r.sub.10 = -62.149 f = 1.0, 1 = 15.0, S = 0.794 IH = 0.89, 2ω

= 118.58°

, Σ

P = -0.007 NA = 0.0127, f.sub.234 /f = 1.610 ##STR27## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference symbol IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum and the reference symbol NA represents numerical aperture.

15. An objective lens system for endoscopes according to claim 1 having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 42.483 d.sub.1 = 0.423 n.sub.1 = 1.51633 ν

.sub.1 = 64.15 r.sub.2 = 0.809 d.sub.2 = 1.259 r.sub.3 = ∞

d.sub.3 = 0.374 r.sub.4 = -42.497 d.sub.4 = 1.032 n.sub.2 = 1.69680 ν

.sub.2 = 55.52 r.sub.5 = -2.358 d.sub.5 = 0.098 r.sub.6 = 7.206 d.sub.6 = 1.032 n.sub.3 = 1.51728 ν

.sub.3 = 69.56 r.sub.7 = -3.096 d.sub.7 = 0.098 r.sub.8 = 2.615 d.sub.8 = 1.770 n.sub.4 = 1.61800 ν

.sub.4 = 63.38 r.sub.9 = -1.658 d.sub.9 = 0.433 n.sub.5 = 1.84666 ν

.sub.5 = 23.90 r.sub.10 = -76.590 f = 1.0, 1 = 15.0, S = 0.794 IH = 0.885, 2ω

= 118°

, Σ

P = 0.015 NA = 0.0129, f.sub.234 /f = 1.562 ##STR28## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference symbol IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum and the reference symbol NA represents numerical aperture.

16. An objective lens system for endoscopes comprising a first negative meniscus lens component having a concave surface on the image side, an aperture stop, a second positive meniscus lens component, a third biconvex lens component and a fourth positive cemented doublet component consisting of a positive lens element and a negative lens element, said lens system having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 28.7611 d.sub.1 = 0.4938 n.sub.1 = 1.58913 ν

.sub.1 = 60.97 r.sub.2 = 0.8457 d.sub.2 = 0.9877 r.sub.3 = ∞

d.sub.3 = 0.6173 r.sub.4 = -99,2330 d.sub.4 = 1.0494 n.sub.2 = 1.6968 ν

.sub.2 = 55.52 r.sub.5 = -2,1786 d.sub.5 = 0.1235 r.sub.6 = 9.2568 d.sub.6 = 1.1111 n.sub.3 = 1.6968 ν

.sub.3 = 55.52 r.sub.7 = -4.4531 d.sub.7 = 0.1235 r.sub.8 = 3.0441 d.sub.8 = 1.7284 n.sub.4 = 1.6180 ν

.sub.4 = 63.38 r.sub.9 = -1.6506 d.sub.9 = 0.4321 n.sub.5 = 1.84666 ν

.sub.5 = 23.90 r.sub.10 = -18.0296 f = 1.0, 1 = 15.0, S = 0.863 IH = 0.889, 2ω

= 117.08°

, Σ

P = 0 NA = 0.0129, f.sub.234 /f = 1.591 ##STR29## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference symbol IH represents height of the image, the reference symbol 2ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum, the reference sumbol NA represents numerical aperture, the reference symbol f represents total focal length of the entire lens system as a whole, and the reference symbol f₂₃₄ designates total focal length of said second, third and fourth lens components as a whole.

17. An objective lens system for endoscopes comprising a first negative meniscus lens component having a concave surface on the image side, an aperture stop, a second positive meniscus lens component, a third biconvex lens component and a fourth positive cemented doublet component consisting of a positive lens element and a negative lens element, said lens system having the following numerical data:

space="preserve" listing-type="tabular">______________________________________ r.sub.1 = 80.059 d.sub.1 = 0.523 n.sub.1 = 1.726 ν

.sub.1 = 53.56 r.sub.2 = 0.945 d.sub.2 = 1.264 r.sub.3 = ∞

d.sub.3 = 0.376 r.sub.4 = -30.452 d.sub.4 = 1.076 n.sub.2 = 1.6968 ν

.sub.2 = 55.52 r.sub.5 = -2.227 d.sub.5 = 0.126 r.sub.6 = 12.588 d.sub.6 = 1.139 n.sub.3 = 1.51728 ν

.sub.3 = 69.56 r.sub.7 = -2.878 d.sub.7 = 0.126 r.sub.8 = 3.426 d.sub.8 = 1.965 n.sub.4 = 1.69249 ν

.sub.4 = 58.56 r.sub.9 = -1.557 d.sub.9 = 0.439 n.sub.5 = 1.92286 ν

.sub.5 = 21.29 r.sub.10 = -36.333 f = 1.0, l = 15.0, S = 1.05 IH = 0.89, 2ω

= 116.69°

, Σ

P = -0.036 NA = 0.0128, f.sub.234 /f = 1.666 ##STR30## ______________________________________

wherein the reference symbols r₁ through r₁₀ represent radii of curvature on the surfaces of the respective lens elements including said stop, the reference symbols d₁ through d₉ designate thicknesses of the respective lens elements and airspaces reserved therebetween, the reference symbols n₁ through n₅ denote refractive indices of the respective lens elements, the reference symbols ν

₁ through ν

₅ represent Abbe'"'"'s numbers of the respective lens elements, the reference symbol 1 designates distance as measured from an object to be observed or photographed to the front surface of the lens system, the reference symbol S denotes distance as measured from the rear surface of the lens system to the image, the reference symbol IH represents height of the image, the reference symbol 2.sub.ω

designates field angle, the reference symbol Σ

P denotes Petzval'"'"'s sum, the reference symbol NA represents numerical aperture, the reference symbol f represents total focal length of the entire lens system as a whole, and the reference symbol f₂₃₄ designates total focal length of said second, third and fourth lens components as a whole.