Fresnel Lens Group Self-Temperature Focus Compensation
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Solution Overview
Problem
Plastic and glass optical lenses experience defocusing due to temperature changes, leading to image degradation, and existing temperature control systems are costly and impractical for consumer and solar power generation applications.
Innovation Solution
A self-temperature focus compensation device using Fresnel lens groups with zero focal power at a specific temperature, comprising a first Fresnel lens with positive focal power and a second Fresnel lens with negative focal power, where the air gaps along the optical axis are greater than zero, allowing the device to compensate for focal power changes caused by temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature control system is used to maintain the temperature of the use environment, then the optical lens can maintain clear image during imaging, but the costs are beyond a range acceptable to common consumers
Solution Approach 1:
The patent extracts the temperature control function from the optical system and replaces it with a dedicated compensation lens group that independently compensates for thermal defocusing. This separation allows the main optical system to remain simple while adding only the necessary compensation elements, thereby reducing overall system cost while maintaining image quality stability.
Solution Approach 2:
The compensation lens group acts as an intermediary element between the objective lens and the image sensor. It mediates the thermal defocusing effect by introducing additional optical power that counteracts the refractive index changes in the plastic lens, thus stabilizing image quality without requiring temperature control of the entire system.
2Reliability
If a temperature control system is used to maintain the temperature of the use environment, then the optical lens can maintain clear image during imaging, but the system becomes impractical for solar power generation applications
Solution Approach 1:
The patent removes the requirement for active temperature control from the system, making it adaptable to applications like solar power generation where temperature control is impractical. The compensation lens group passively compensates for thermal effects without requiring power or control systems, enabling deployment in diverse environments including outdoor solar applications.
Solution Approach 2:
The compensation lens group is designed to automatically compensate for thermal defocusing without external control. The air gaps between lens elements expand or contract with temperature changes, naturally adjusting the optical power to counteract refractive index changes in the plastic lens, making the system self-regulating and adaptable to various applications.
3Ease of manufacture
If plastic lenses are used due to low costs and easy processing, then manufacturing cost is reduced, but the refractive index changes with temperature causing defocusing
Solution Approach 1:
The patent creates a composite optical system combining plastic lenses (for cost and ease of manufacture) with a compensation lens group containing elements of different materials (glass and plastic with different thermal properties). This composite structure allows the inexpensive plastic objective lens to be paired with compensation elements that counteract its thermal defocusing, achieving both low cost and focus stability.
Solution Approach 2:
The patent utilizes changes in physical parameters (air gap dimensions) in response to temperature changes to compensate for refractive index changes in the plastic lens. The air gaps expand when temperature increases, reducing the optical power of the compensation lens group, which counteracts the increase in optical power caused by refractive index changes in the plastic lens, thereby maintaining focus stability.
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 device effectively maintains image quality by compensating for focal power changes at varying temperatures, reducing costs and system deformation, making it suitable for most lens groups and applications, including solar power generation systems.
Implementation Method 1
Air gaps of the first Fresnel lens and the second Fresnel lens along an optical axis of the Fresnel lens group of the first Fresnel lens and the second Fresnel lens are greater than zero
Implementation Method 2
a refractive index of the plastic lens is likely to change with a temperature change, changing a focus of the optical lens
Data Source
AI summary
A self-temperature focus compensation device adapted to cooperate with a lens group and including at least one Fresnel lens group is provided. Each Fresnel lens group has zero focal power at a specific temperature and is a cemented lens. Each Fresnel lens group includes a first Fresnel lens and a second Fresnel lens. The first Fresnel lens has positive focal power. The second Fresnel lens has negative focal power. A sum of a focal power change of the at least one Fresnel lens group with a temperature change and a focal power change of the lens group with the temperature change is zero.