Sensor Holder Thermal Compensation for Camera Alignment
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Solution Overview
Problem
Conventional imaging systems face misalignment and focus issues due to thermal cycling caused by differing coefficients of thermal expansion in various materials, leading to debowing and destressing, which affects the accuracy of image capture in fixed focus cameras.
Innovation Solution
An optical system is designed with a sensor holder that positions the image sensor along the optical axis and at the focal plane, using a substrate and lens assembly with materials like ceramic or glass-reinforced epoxy, and an active alignment process to maintain the image sensor's position within a few microns of the focal plane across multiple thermal cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional imaging systems use multiple materials with differing coefficients of thermal expansion, then the system can be manufactured with available materials, but thermal cycling causes misalignment and focus issues
Solution Approach 1:
The patent changes the physical parameters of the substrate by selecting materials with specific thermal expansion properties. The substrate is designed to have a coefficient of thermal expansion that matches or compensates for the combined thermal expansion of the lens assembly and image sensor, thereby maintaining focal plane alignment during thermal cycling.
Solution Approach 2:
The patent employs composite material strategies by using a substrate made from materials like ceramic or glass-reinforced epoxy that exhibit controlled thermal expansion characteristics. These composite materials are selected to harmonize the thermal behavior of different system components, preventing misalignment while maintaining manufacturability.
2Measurement precision
If the image sensor position is maintained across thermal cycles, then focus accuracy is improved, but the system becomes more sensitive to thermal expansion differences
Solution Approach 1:
The patent converts the harmful effect of thermal expansion into a beneficial outcome by designing the substrate to actively compensate for thermal cycling. The substrate's thermal expansion properties are selected to counterbalance the thermal expansion of other components, so that temperature changes that would normally cause misalignment instead maintain the image sensor at the correct focal plane.
3Manufacturing precision
If a sensor holder is used to position the image sensor, then alignment precision is improved, but the device complexity increases
Solution Approach 1:
The patent merges the substrate and sensor holder functions into a single integrated component. The substrate itself is designed with features that directly position and secure the image sensor, eliminating the need for a separate sensor holder assembly. This integration maintains precise alignment while reducing overall system complexity.
4Stability of the object's composition
If materials with matched thermal expansion coefficients are selected, then thermal stability is improved, but material selection becomes more restrictive
Solution Approach 1:
The patent changes the approach from selecting materials based on mechanical or optical properties alone to selecting materials based on their thermal expansion parameters. By prioritizing thermal compatibility, the system achieves stable performance across temperature ranges while working within practical material selection constraints.
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
This configuration ensures accurate focus and reduces thermal-cycle-induced misalignment, maintaining image sensor position and image quality over a wide temperature range, enhancing the reliability of fixed-focal length imaging systems.
Implementation Method 1
thermal cycling caused by differing coefficients of thermal expansion in various materials
Implementation Method 2
positions the image sensor along the optical axis and substantially at the focal plane
Data Source
AI summary
The present disclosure relates to optical systems and methods of their manufacture. An example optical system includes a lens assembly having at least one lens. The lens assembly defines an optical axis, a focal distance, and a corresponding focal plane. The optical system includes a substrate having a first surface and an image sensor attached to the first surface of the substrate. The optical system also includes a sensor holder attached to the first surface of the substrate. The sensor holder positions the image sensor along the optical axis and substantially at the focal plane. The optical system includes a registration body having a first registration surface and a second registration surface. The lens assembly is coupled to the first registration surface and the sensor holder is coupled to the second registration surface.