Five-Lens Camera Group for TOF Temperature Stability
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Solution Overview
Problem
Current camera lenses for Time of Flight (TOF) technology face challenges in achieving a large relative aperture, ultra-wide angle, and temperature stability while maintaining imaging quality, particularly in TOF cameras that require specific optical designs to handle temperature drift and large chief ray angles.
Innovation Solution
A camera lens group comprising five lenses with carefully configured refractive powers, surface shapes, and interval distances along the optical axis, including a stop and glass lenses with controlled thermal expansion coefficients, to optimize the field of view, reduce temperature drift, and enhance imaging quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a lens is designed with large relative aperture for TOF camera, then the light gathering capability is improved, but the chief ray incident angle becomes large causing imaging quality degradation
Solution Approach 1:
The lens is divided into five separate lens elements (first through fifth lenses) with alternating positive and negative refractive powers. This segmentation allows each element to be optimized for specific functions: the negative power lenses control the chief ray angles, while the positive power lenses provide light gathering capability, resolving the contradiction between large aperture and imaging quality
Solution Approach 2:
Different regions of the lens system are assigned different optical properties. The first and second lenses have negative refractive powers specifically to control chief ray angles at the image periphery, while the third, fourth, and fifth lenses have positive refractive powers to provide overall light gathering. This local differentiation allows simultaneous optimization of both aperture and imaging quality
2Volume of moving object
If the lens structure is made compact for portability, then the device size is reduced, but temperature drift control becomes more difficult
Solution Approach 1:
The patent specifies precise parameter ranges for each lens element including focal lengths (e.g., −0.451 < f1/f < −0.102), spacing distances (e.g., 0.545×10 < T45×10/TTL < 1.1), and thermal expansion coefficients (TCE < 6×10^−6/K). These controlled parameters maintain temperature stability while allowing compact overall dimensions
Solution Approach 2:
The lens system uses glass materials with specifically controlled thermal expansion coefficients (TCE < 6×10^−6/K) to minimize thermal effects. This material selection enables the compact lens design to maintain dimensional stability across temperature variations, resolving the contradiction between size and temperature drift
3Area of moving object
If ultra-wide angle capability is achieved through specific lens configuration, then the field of view is expanded, but the lens complexity increases
Solution Approach 1:
The ultra-wide angle capability is achieved by segmenting the lens into five elements with alternating positive and negative powers. The negative power first and second lenses specifically control off-axis rays to enable wide field of view (half maximum field of view satisfying 0.8 < tan(HFOV/2) < 1.3), while the subsequent positive power lenses correct the introduced aberrations, managing the complexity through functional division
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a camera lens group that achieves ultra-wide angle capabilities, reduces temperature drift, and supports large aperture requirements, improving imaging quality and resolution while ensuring compactness and processability for TOF cameras.
Implementation Method 1
a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are arranged from an object side to an image side along an optical axis. The first lens has a negative refractive power; the second lens has a negative refractive power; the third lens has a positive refractive power or a negative refractive power
Data Source
AI summary
The present disclosure discloses a camera lens group including, sequentially from an object side to an image side of the camera lens group along an optical axis, a first lens, a second lens, a third lens, a fourth lens and a fifth lens. The first lens has a negative refractive power; the second lens has a negative refractive power; the third lens has a refractive power, and an object-side surface of the third lens is concave; the fourth lens has a positive refractive power, an object-side surface of the fourth lens is convex, and an image-side surface of the fourth lens is convex; and the fifth lens has a refractive power. A half of a maximum field of view HFOV of the camera lens group satisfies 0.8<tan(HFOV/2)<1.2.