Collimator Lens Diffractive Structure Thermal Compensation
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Solution Overview
Problem
Existing optical scanning devices face challenges in maintaining imaging performance due to temperature changes, particularly with collimator lenses made from resin materials, which affect refractive index and lead to thermal deformation, causing fluctuations in imaging position and aberrations, and the use of inexpensive materials with high linear expansion coefficients results in insufficient imaging performance.
Innovation Solution
A collimator lens with a diffractive structure on at least one of its faces, designed to convert divergent light into convergent light, where the wavefront aberration of divergent light is minimized compared to parallel light, and the diffractive structure compensates for thermal expansion, ensuring superior imaging performance across a temperature range of 0°C to 60°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a collimator lens is molded from a resin material, then manufacturing cost is reduced and ease of manufacture is improved, but imaging performance deteriorates due to temperature-induced refractive index changes and thermal deformation
Solution Approach 1:
The patent introduces a diffractive structure on the lens surface that changes its optical parameters in response to temperature variations. The diffractive structure's diffraction characteristics vary with temperature to compensate for the resin material's refractive index changes, maintaining imaging performance across different temperatures while using inexpensive molded resin lenses.
Solution Approach 2:
The patent combines a resin lens material with a diffractive optical structure to create a composite optical element. The resin provides the basic lens function and thermal expansion characteristics, while the diffractive structure (formed by microlens arrays or surface relief patterns) provides temperature compensation, achieving both ease of manufacture and maintained imaging performance.
2Temperature
If the ambient temperature changes, then the refractive index of the lens component varies and thermal deformation occurs, but these changes cause imaging position shifts and aberrations that worsen imaging performance
Solution Approach 1:
The diffractive structure is designed to change its optical parameters (diffraction efficiency, focal length) as temperature varies. This parameter change compensates for the resin lens's thermal effects, maintaining stable imaging performance across the temperature range of 0°C to 60°C despite refractive index variations and thermal deformation.
Solution Approach 2:
The patent converts the harmful thermal expansion and refractive index changes of the resin material into a beneficial effect. By designing the diffractive structure to have opposite thermal characteristics, the harmful thermal effects are transformed into a compensating mechanism that maintains imaging performance.
3Ease of manufacture
If inexpensive materials with large linear expansion coefficients are used for the housing, then manufacturing cost is reduced, but imaging performance becomes insufficient due to thermal expansion affecting optical component distances
Solution Approach 1:
The diffractive structure's temperature-dependent optical parameters compensate for distance changes caused by housing thermal expansion. As temperature increases and the housing expands changing component distances, the diffractive structure's parameters change to compensate, maintaining imaging performance despite using inexpensive thermally expandable housing materials.
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 effectively maintains superior imaging performance and compensates for thermal expansion, allowing the use of thermally expandable resin housing while ensuring the collimator lens maintains optimal imaging quality, even with temperature changes, thus addressing the limitations of existing technologies.
Implementation Method 1
a diffractive structure which is formed on at least one of the first face and the second face
Implementation Method 2
the diffractive structure compensates for thermal expansion, ensuring superior imaging performance across a temperature range of 0°C to 60°C
Implementation Method 3
a collimator lens which converts, into convergent light, a light beam of divergent light emitted from a light source
Data Source
AI summary
In a collimator lens, in a case where divergent light emitted from a position P1 at a distance S1 from a second face enters the second face and imaging is performed at a position P2 at a distance S2 from a first face, in a temperature range of 0° C. to 60° C. and in a range of the emission wavelength of the light source which changes within the temperature range, and when a minimum value of a wavefront aberration of an image, which is generated at the position P2 by the divergent light emitted from the position P1 in a range of 0<S1/S2≦̸50, is WF1, and when a minimum value of a wavefront aberration of an image, which is generated at the position P2 when parallel light satisfying S1=∞ enters the second face, is WF2, a relationship of WF1<WF2 is satisfied.