Spectroscopic Sensor Interference Filter Noise Light Protection
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Solution Overview
Problem
Conventional spectroscopic sensors face issues with filter characteristic deterioration and noise light entry due to adverse effects on the optical filter unit's side face, leading to compromised performance.
Innovation Solution
The design incorporates an interference filter unit with a ring-shaped second filter region surrounding the first filter region, where the distance between mirror layers is fixed in the second region, narrowing the wavelength range and preventing noise light entry, while the second region protects the first filter region from external forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical filter unit is provided so as to correspond to a light-receiving surface of the light detection substrate and functions as a whole as a filter region, then the filter can transmit light to be incident on the light-receiving surface, but filter characteristics may immediately deteriorate if a side face of the optical filter unit is adversely affected and noise light may easily enter from the side face
Solution Approach 1:
The optical filter unit is divided into a first filter region corresponding to the light-receiving surface and a second filter region surrounding the first filter region. This segmentation allows the second filter region to protect the first filter region from side face adverse effects while the first filter region maintains its light transmission function.
Solution Approach 2:
The second filter region acts as an intermediary protective structure between the external environment and the first filter region. It blocks noise light and adverse effects from reaching the first filter region's side face, while allowing the first filter region to function normally.
2Measurement precision
If the distance between mirror layers is varied in the first filter region to selectively transmit light, then wavelength-selective transmission is achieved, but the side face remains vulnerable to adverse effects and noise light entry
Solution Approach 1:
Different regions of the optical filter unit are assigned different functions: the first filter region has variable mirror layer distances for wavelength-selective transmission, while the second filter region has fixed mirror layer distances for protection and noise light blocking. Each region's structure is optimized for its specific function.
3Reliability
If a ring-shaped second filter region surrounds the first filter region with fixed mirror layer distance, then noise light entry is restrained and filter characteristics are protected, but device complexity increases
Solution Approach 1:
The first and second filter regions are merged into a single interference filter unit, sharing common mirror layers and cavity structures. This integration achieves protection and noise light restraint functions while avoiding the complexity of completely separate filter units.
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 effectively prevents filter characteristic deterioration and reduces noise light entry, enhancing the spectroscopic sensor's performance by stabilizing the filter regions and improving light detection accuracy.
Implementation Method 1
an interference filter unit, having a cavity layer and first and second mirror layers opposing each other through the cavity layer, for selectively transmitting therethrough a predetermined wavelength range of light according to an incident position thereof from the first mirror layer side to the second mirror layer side
Data Source
AI summary
A spectroscopic sensor 1A comprises an interference filter unit 20A having a cavity layer 21 and first and second mirror layers 22, 23 and a light detection substrate 30 having a light-receiving surface 32a for receiving light transmitted through the interference filter unit 20A. The interference filter unit 20A has a first filter region 24 corresponding to the light-receiving surface 32a and a ring-shaped second filter region 25 surrounding the first filter region 24. The distance between the first and second mirror layers 22, 23 varies in the first filter region 24 and is fixed in the second filter region 25.