Collimating Array for Optical Sensor Angular Control
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Solution Overview
Problem
Spectroscopy devices using interference-based filters, such as Fabry-Pérot filters, face performance issues due to strong angular dependency, where light incident at angles greater than ±10° can cause filter response shifts and widening, affecting the stability and uniformity of spectral measurements.
Innovation Solution
The implementation of a collimated beam of light and an angle-of-incidence device with an array of pinhole elements or a fiber-optic plate is used to limit the angle of incidence, ensuring that light striking the filter array is substantially collimated, thereby maintaining a stable and uniform spectral response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If light is allowed to incident on the filter array at wide angles, then the field of view and light collection efficiency are improved, but the filter response shifts and widens causing measurement instability
Solution Approach 1:
A collimating lens is introduced as an intermediary optical element between the sample and the filter array. This lens collimates the light before it reaches the filters, ensuring that light rays incident on the filters are parallel and within the acceptable angular range. This mediator resolves the contradiction by enabling efficient light collection while maintaining spectral measurement stability through angular control.
Solution Approach 2:
The patent controls the angular parameter of incident light by using a collimating lens to transform divergent light into parallel beams. By changing the angular distribution parameter of the light (from wide angles to narrow collimated angles), the system maintains filter response stability while still achieving adequate light collection for spectroscopy measurements.
2Measurement precision
If a collimating lens is added to control the angle of incidence, then the spectral measurement stability is improved, but the device complexity increases
Solution Approach 1:
The collimating lens serves multiple functions simultaneously: it collimates the light to control angle of incidence, focuses light to improve collection efficiency, and defines the field of view for the spectroscopy measurement. By making the optical element multi-functional, the patent reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving spectral measurement stability.
3Reliability
If the angle of incidence is strictly limited, then the filter response stability is improved, but the light collection efficiency decreases
Solution Approach 1:
The collimating lens provides partial collimation rather than perfect parallelism, achieving sufficient angular control to maintain filter response stability within acceptable tolerances. This partial action is adequate to resolve the stability issue while allowing some angular spread that maintains adequate light collection efficiency, avoiding the need for overly restrictive angular limiting that would excessive reduce light throughput.
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 approach effectively limits the angle of incidence, reducing the impact of angular dependence on the filter response, resulting in a more stable and uniform spectral measurement across the sensor array, which is essential for diffuse optical spectroscopy applications.
Implementation Method 1
The implementation of a collimated beam of light and an angle-of-incidence device with an array of pinhole elements or a fiber-optic plate is used to limit the angle of incidence, ensuring that light striking the filter array is substantially collimated
Implementation Method 2
Interference-based filters, such as Fabry-Pérot filters, when used in conjunction with spectroscopy, have been shown to be capable of providing useful spectral information. Light traveling through interference-based filters at an angle incident to a sensor surface of more than a relatively small amount can negatively impact a sensors performance.
Data Source
AI summary
An optical sensor system comprises an array of optical sensors arranged on an integrated circuit and a plurality of filters with the bottom surface of the plurality of filters located above the top surface of the array of optical sensors. The optical sensor system further comprises an angle-of-incidence layer that includes a top surface, a bottom surface, and a thickness Y, where the bottom surface of the angle-of-incidence layer is located a predetermined distance X from the top surface of the plurality of filters and the angle-of-incidence layer includes a plurality of collimating elements, with each collimating element of the angle-of-incidence layer having an aperture width Z.