Imaging system and bimodal zoom lens thereof

• US 11,061,211 B2
• Filed: 01/09/2019
• Issued: 07/13/2021
• Est. Priority Date: 01/09/2019
• Status: Active Grant

• Current Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Original Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Inventors: Cheng, Tingyu, Deng, Jau-Jan
• Primary Examiner(s): Lei, Jie
• Application Number:
  US16/243,935
• Publication Number:
  US 20200218043A1
• Time in Patent Office: 916 Days
• Field of Search: 359684, 359689, 359716, 359748, 359753, 359784, 359787, 359790
• CPC Class Codes: G02B 13/0035 having three lenses
• CPC Class Codes: G02B 15/04 by changing a part
• CPC Class Codes: G02B 15/143507 arranged -++
• CPC Class Codes: G02B 15/177 having a negative front lens or group of lenses
• CPC Class Codes: G02B 15/20 having an additional movable lens or lens group for varying the objective focal length
• CPC Class Codes: G02B 23/2438 Zoom objectives
• CPC Class Codes: G02B 23/2446 of the image relay G02B23/26 takes precedence

Abstract

A bimodal zoom lens includes three coaxially aligned lenses including a first lens, a third lens, and a second lens therebetween. The first lens is a negative lens, each of the second lens and the third lens is a positive lens. The three coaxially aligned lenses form (i) a first configuration when the second lens and the first lens are separated by an axial distance L₁₁ and (ii) a second configuration when the second lens and the first lens are separated by an axial distance L₁₂, which exceeds axial distance L₁₁. The second configuration has a second effective focal length that exceeds a first effective focal length of the first configuration.

Claims

1. A bimodal zoom lens comprising:

three coaxially aligned lenses including a first lens, a third lens, and a second lens therebetween,

the first lens being a negative simple lens, each of the second lens and the third lens being a positive lens,

the second lens being a multi-element lens that includes an object-side plano-convex positive lens and, at a fixed axial distance therefrom, an image-side plano-convex positive lens located between the third lens and the object-side plano-convex positive lens; and

a substrate between the object-side plano-convex positive lens and the image-side plano-convex positive lens and including a planar object-side surface and a planar image-side surface, the object-side plano-convex positive lens being disposed on the planar object-side surface, the image-side plano-convex positive lens being disposed on the planar image-side surface;

the three coaxially aligned lenses being configurable in (i) a first configuration when the second lens and the first lens are separated by an axial distance L₁₁ and (ii) a second configuration when the second lens and the first lens are separated by an axial distance L₁₂, which exceeds axial distance L₁₁,

the first configuration having a first effective focal length that exceeds a second effective focal length of the second configuration.

2. The bimodal zoom lens of claim 1,

in the first configuration, the second lens and the third lens being separated by an axial distance L₃₁ that exceeds the axial distance L₁₁ between the second lens and the first lens;

in the second configuration, the second lens and the third lens being separated by an axial distance L₃₂ that is less than the axial distance L₁₂ between the second lens and the first lens.

3. The bimodal zoom lens of claim 1, the first configuration having a total track length T₁, the second configuration having a total track length T₂, wherein 0.9925<

T₁/T₂<

1.0075.

4. The bimodal zoom lens of claim 1, the second configuration having a second field of view that exceeds a first field of view of the first configuration.

5. The bimodal zoom lens of claim 1, ratio of the first effective focal length to the second effective focal length exceeding 1.99.

6. The bimodal zoom lens of claim 1, ratio of a first focal length, of the first lens, the first effective focal length being between −

1.02 and zero.

7. The bimodal zoom lens of claim 1, further comprising a substrate between the object-side plano-convex positive lens and the image-side plano-convex positive lens.

8. The bimodal zoom lens of claim 7, the substrate being formed of a substrate material that differs from a second-lens material forming the second lens and a third-lens material forming the third lens.

9. The bimodal zoom lens of claim 1, ratio of a focal length, of the image-side plano-convex positive lens, to the first effective focal length being positive and less than 1.54.

10. The bimodal zoom lens of claim 1, the object-side plano-convex positive lens being formed of a material having an Abbe number less than thirty-five.

11. The bimodal zoom lens of claim 1, the first lens and the third lens being separated by a fixed axial distance, which is invariant between the first configuration and the second configuration.

12. An imaging system comprising:

an image sensor; and

the bimodal zoom lens of claim 1, configured to form an image on a pixel array of the image sensor.

13. The imaging system of claim 12, the image sensor including a pixel array having a width and a height in a plane perpendicular to an optical axis common to the three coaxially aligned lenses, at least one of the width and the height being less than 1.1 millimeters.

14. The imaging system of claim 12, wherein the imaging system is part of an endoscope.

15. The imaging system of claim 12, the second configuration having a second field of view that exceeds a first field of view of the first configuration.

16. The bimodal zoom lens of claim 1, the first lens including a single object-side surface and a single image-side surface.