Collimator Lens System Thermal Stability
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Solution Overview
Problem
Existing collimator lens systems experience significant changes in focal length and light angle due to temperature variations, leading to errors in 3D imaging accuracy and clarity.
Innovation Solution
A collimator lens system comprising a first positive focal power lens, a second negative focal power lens, and a third positive focal power lens, with specific refractive index change rates and optical configurations to maintain a stable focal length across temperature changes, including aspheric surfaces and independent lenses made of plastic and glass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional collimator lens system is used, then the structure is simple, but the focal length changes greatly with temperature, causing light angle changes and reducing imaging accuracy
Solution Approach 1:
The collimator lens system is divided into three separate lenses with different focal powers arranged in sequence: a first lens with positive focal power, a second lens with negative focal power, and a third lens with positive focal power. This segmentation allows each lens to contribute differently to temperature compensation, with the first and third lenses providing converging power and the second lens providing diverging power to offset thermal expansion effects collectively
Solution Approach 2:
The patent specifies precise parameter ranges for each lens including focal lengths (f1, f2, f3), refractive index temperature coefficients ((dn/dt)1, (dn/dt)2, (dn/dt)3), and spacing distances (d1, d2, d3). By carefully controlling these parameters, the system achieves temperature compensation where the focal length change rates of individual lenses combine to minimize overall focal length variation with temperature
2Stability of the object's composition
If the focal length is made stable across temperatures, then imaging accuracy is maintained, but the lens system becomes more complex with multiple lenses and specific configurations
Solution Approach 1:
The patent utilizes the thermal expansion properties of lens materials by selecting lenses with specific refractive index temperature coefficients. The first lens has (dn/dt)1 between -50×10^-6/°C and -20×10^-6/°C, the second lens has (dn/dt)2 between -50×10^-6/°C and -30×10^-6/°C, and the third lens has (dn/dt)3 greater than -10×10^-6/°C. These different thermal characteristics allow the lenses to compensate for each other's focal length changes when subjected to temperature variations
Solution Approach 2:
The collimator lens system employs a composite configuration of three lenses made from materials with different thermal-optical properties. The combination of materials with varying refractive index temperature coefficients creates a composite optical system that achieves thermal stability, where the aggregate focal length remains relatively constant across temperature ranges despite individual lens variations
3Adaptability or versatility
If ambient temperature changes, then the lens system adapts to new conditions, but the focal length changes significantly, causing light angle variation and reducing 3D imaging quality
Solution Approach 1:
The patent defines specific parameter ranges for the lens system to maintain performance across temperature variations. The focal lengths (f1, f2, f3), spacing distances (d1, d2, d3), and refractive index temperature coefficients ((dn/dt)1, (dn/dt)2, (dn/dt)3) are carefully selected so that the system adapts to temperature changes while keeping the overall focal length and light angle within acceptable tolerances for accurate 3D imaging
Solution Approach 2:
The patent converts the harmful effect of temperature-induced refractive index changes into a beneficial compensation mechanism. By using lenses with specific refractive index temperature coefficients that vary in sign and magnitude, the thermal expansion of one lens is compensated by the thermal contraction or different expansion of another lens, transforming what would be a source of error into a self-correcting system
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 system ensures minimal change in focal length and light angle with temperature, maintaining image clarity and accuracy by offsetting thermal expansion effects, resulting in stable 3D imaging performance.
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 negative focal power; the third lens is of a positive focal power
Implementation Method 2
a focal length of a lens changes greatly with the change of ambient temperature... (dn/dt)1 represents a change rate of a refractive index of the first lens with temperature, (dn/dt)2 represents a change rate of a refractive index of the second lens with temperature, and (dn/dt)3 represents a change rate of a refractive index of the third lens with temperature
Data Source
AI summary
A collimator lens system includes a first lens, a second lens, a third lens and a diaphragm from an object side to an image side of the system 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 negative focal power; the third lens is of a positive focal power, and an image side surface thereof is convex; optical centers of all the lenses are arranged along a same straight line, the system meets following formulas: f12>f3; (dn/dt)1<−50×10−6/° C.; (dn/dt)2<−50×10−6/° C.; (dn/dt)3>−10×10−6/° C., where f12 represents a combined focal length of the first and second lenses, f3 represents a focal length of the third lens, and (dn/dt)1, (dn/dt)2, and (dn/dt)3 represent change rates of refractive indices of the first lens, the second lens and the third lens with temperature, respectively.