Collimator Lens Thermal Stability via Refractive Index Compensation
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Solution Overview
Problem
Existing collimator lenses experience significant changes in focal length and light angle due to temperature variations, leading to errors in 3D imaging and reduced clarity of reconstructed three-dimensional objects.
Innovation Solution
A collimator lens design comprising a first and second lens with specific focal power and refractive index change rates, along with aspheric surfaces and independent non-bonded lenses, ensures a stable focal length across temperatures by configuring the optical elements to offset thermal expansion effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional collimator lens is used, then the lens can project laser information onto the object surface, but the focal length changes significantly with temperature, causing light angle changes and imaging errors
Solution Approach 1:
The patent changes the material parameter (refractive index temperature coefficient) by selecting specific glass materials with different thermal characteristics for the first and second lenses. The first lens uses material with (dn/dt)1 between -16×10^-6/°C to -6×10^-6/°C, while the second lens uses material with (dn/dt)2 greater than -10×10^-6/°C, creating a composite system that compensates for thermal focal length drift.
Solution Approach 2:
The patent employs a composite lens system where the first lens and second lens are made from different glass materials with complementary thermal properties. This composite structure allows the positive thermal expansion of one material to compensate for the negative thermal expansion of the other, stabilizing the overall focal length across temperature variations.
2Stability of the object's composition
If the focal length changes with temperature, then the light projection angle changes, but this causes errors in light information calculation and profile reconstruction
Solution Approach 1:
The patent modifies the optical parameters of the lens system by selecting materials with specific refractive index temperature coefficients and designing asymmetric focal lengths (f1 > f2) with specific ratio relationships. This parameter optimization ensures that the light projection angle remains stable despite temperature changes, preventing information loss in 3D reconstruction.
3Adaptability or versatility
If image points become larger with temperature changes, then the system can adapt to thermal expansion, but this leads to sharpness reduction and clarity loss
Solution Approach 1:
The patent divides the collimator lens into two separate lens elements (first lens and second lens) with different thermal characteristics. This segmentation allows each lens to be optimized for specific thermal compensation functions, preventing the sharpness reduction that would occur in a monolithic lens design subjected to thermal stress.
Solution Approach 2:
The patent applies different material qualities to different parts of the optical system. The first lens uses material with lower thermal expansion characteristics while the second lens uses material with higher thermal stability, creating local quality differences that collectively maintain overall image sharpness across temperature variations.
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 consistent light projection angles and original light formation, enhancing the accuracy and clarity of 3D imaging by stabilizing the focal length and reducing aberrations across varying temperatures.
Implementation Method 1
the first lens is of a positive focal power, an object side surface of the first lens is convex; the second lens is of a positive focal power, an image side surface of the second lens is convex
Implementation Method 2
a focal length of a lens changes greatly with the change of ambient temperature
Implementation Method 3
where (dn/dt)1 represents a change rate of a refractive index of the first lens with temperature, and (dn/dt)2 represents a change rate of a refractive index of the second lens with temperature
Data Source
AI summary
A collimator lens includes a first lens, a second lens and a diaphragm from an object side to an image side of the assembly in turn along an optical axis, in which the first lens is of a positive focal power, and an object side surface thereof is convex; the second lens is of a positive focal power, and an image side surface thereof is convex; optical centers of the first lens and the second lens are arranged along a same straight line, the system meets following formulas: f1>f2; (dn/dt)1<−50×10−6/° C.; (dn/dt)2>−10×10−6/° C., where f1 represents a focal length of the first lens, f2 represents a focal length of the second lens, (dn/dt)1 represents a change rate of a refractive index of the first lens with temperature, and (dn/dt)2 represents a change rate of a refractive index of the second lens with temperature.