Collimating Lens Thermal Stability via Glass-Plastic Composite Design
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Solution Overview
Problem
Conventional collimating lenses for 3D imaging technology experience significant changes in focal length and light angle due to temperature variations, leading to errors in contour restoration and reduced sharpness, and are prone to aging, making them unreliable.
Innovation Solution
A collimating lens design comprising a first lens with positive refractive power, a second lens with negative refractive power, and a third lens with positive refractive power, where the optical centers are aligned, and the refractive index change rates are carefully managed to stabilize focal length and reduce thermal expansion effects, with the first lens made of glass near the laser emitter to delay aging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional plastic lens is used in the collimating lens, then the manufacturing cost is reduced and ease of manufacture is improved, but the reliability deteriorates due to aging and difficulty in passing reliability tests
Solution Approach 1:
The patent changes the material parameter of the first lens from plastic to glass, which has different thermal and optical properties. This material substitution resolves the contradiction by using glass that resists aging better (improving reliability) while maintaining manufacturability through standard glass lens fabrication processes
Solution Approach 2:
The patent employs a composite lens structure where the first lens is made of glass and the second and third lenses are made of plastic. This composite approach allows the system to benefit from both materials: glass provides stability and reliability for the critical first lens position, while plastic maintains ease of manufacture and cost-effectiveness for the other lenses
2Device complexity
If the focal length of the lens changes with temperature, then the lens structure is simple, but the measurement precision deteriorates due to errors in contour restoration
Solution Approach 1:
The patent carefully selects and controls the refractive index parameters of the lens materials to minimize temperature dependence. By choosing materials with appropriate thermal coefficients and optimizing the lens design parameters, the system achieves temperature-stable focal length while maintaining structural simplicity
Solution Approach 2:
The patent addresses thermal expansion effects by selecting materials and designing the lens structure to compensate for temperature-induced dimensional changes. The glass-plastic composite structure and optimized curvature parameters help mitigate thermal expansion impacts on focal length, maintaining measurement precision without adding complex temperature compensation mechanisms
3Device complexity
If the imaging point of the collimating lens becomes larger with temperature changes, then the lens design is simple, but the manufacturing precision deteriorates due to reduced sharpness of the three-dimensional object
Solution Approach 1:
The patent optimizes the refractive index parameters and lens curvature to maintain a consistent imaging point size across temperature variations. By carefully controlling the thermal optical properties of the glass and plastic materials, the system achieves temperature-invariant imaging characteristics without complicating the lens design
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 design maintains a stable focal length and reduces light angle variations, enhancing the accuracy and reliability of 3D imaging, while being more resistant to temperature changes and easier to test for reliability.
Implementation Method 1
a first lens with positive refractive power, including a convex object side surface
Implementation Method 2
a second lens with negative refractive power, including a concave object side surface
Implementation Method 3
a third lens with positive refractive power, including a convex image side surface
Data Source
AI summary
The disclosure provides a collimating lens. In order from a laser transmitter side to a to-be-measured object side, the collimating lens includes a first lens, a second lens, a third lens and an aperture stop. The first lens is a lens with positive power and includes a convex object side surface. The second lens is a lens having negative power and includes a concave object side surface. The third lens is a lens having positive power and includes a convex image side surface. The change rate of the refractive index of the first lens with temperature in the range of 0 to 60° C. satisfies that (dn/dt)1>−10×10−6/° C. So, the aging of the lens can be effectively delayed. With the same size laser transmitter, the focal length of the system is larger, the field of view angle is smaller.