Self-Aligned Optical Cavities for Infrared Sensor Arrays
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Solution Overview
Problem
Existing infrared sensor arrays face challenges in maintaining consistent optical cavity length due to warping, leading to variations in sensor reflector distance and reduced sensitivity and resolution.
Innovation Solution
Integrating individual optical cavities with each sensor, using metal and dielectric layers deposited on the sensor chip, to maintain consistent cavity dimensions and reduce crosstalk between sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common reflector is used for multiple sensors, then device complexity is reduced, but manufacturing precision deteriorates due to warping causing inconsistent cavity lengths
Solution Approach 1:
The patent divides the single common reflector into multiple individual reflectors, each dedicated to a specific sensor. This segmentation ensures that each sensor-reflector pair maintains a consistent quarter-wave cavity length independent of warping effects, thereby resolving the contradiction between device complexity and manufacturing precision.
Solution Approach 2:
The patent implements locally optimized reflector positions for each sensor based on its specific location and wavelength requirements. Each reflector is individually positioned to maintain the precise quarter-wave distance from its corresponding sensor, allowing local quality customization that compensates for global warping effects.
2Productivity
If sensors are placed close together to increase array density, then productivity increases, but object-generated harmful factors worsen due to increased crosstalk between sensors
Solution Approach 1:
The patent segments the optical path for each sensor using individual reflectors and separate optical cavities. This segmentation creates isolated optical channels that prevent infrared radiation from adjacent sensors from interfering with each other, thereby eliminating crosstalk even when sensors are densely packed.
Solution Approach 2:
The patent introduces individual optical cavities as intermediary structures between adjacent sensors. These cavities act as optical isolators that guide and contain the infrared radiation paths, preventing radiation from one sensor from reaching adjacent sensors and thus reducing crosstalk.
3Ease of manufacture
If the optical cavity length varies due to warping, then ease of manufacture is improved, but measurement precision deteriorates due to reduced sensitivity and resolution
Solution Approach 1:
The patent segments the optical cavity system into multiple independent sensor-reflector-cavity units. Each unit maintains its own quarter-wave cavity length independently, so warping of the overall array does not affect the precision of individual sensor measurements, thereby preserving measurement precision while allowing manufacturing flexibility.
Solution Approach 2:
The patent adjusts the reflector positions and cavity dimensions for each individual sensor to compensate for local warping effects. By changing the geometric parameters of each cavity to maintain the precise quarter-wave length, the system preserves measurement precision despite variations in the overall array structure.
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
Enhances sensitivity and wavelength selectivity by maintaining consistent cavity dimensions and reducing crosstalk, improving the overall resolution of the sensor array.
Implementation Method 1
an individual reflector, formed integrally with the sensor at a location separated from the sensor by one quarter wave at a selected wavelength of the infrared radiation
Implementation Method 2
an open optical cavity between the sensor and the individual reflector
Data Source
AI summary
A sensing device includes an array of sensing elements. Each sensing element includes a thermal infrared sensor, configured to output an electric signal in response to an intensity of infrared radiation that is incident on the sensor. An individual reflector is formed integrally with the sensor at a location separated from the sensor by one quarter wave at a selected wavelength of the infrared radiation.