Optical Module Asymmetric Baffle for ToF Stray Light Control
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Solution Overview
Problem
Optical sensing systems face challenges in minimizing stray radiation that reflects internally within a compact package containing both a transmitter and a receiver, which degrades performance by adding noise to the receiver's signals, especially in ToF-based depth sensing.
Innovation Solution
An asymmetrical optical baffle is used to block stray radiation preferentially, allowing ancillary components to be mounted closely and enabling controlled stray light for ToF calibration, with options for apertures or light guides to manage stray light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a compact package is used to integrate transmitter and receiver on the same substrate, then device size is reduced and integration is improved, but stray radiation from the transmitter reaches the receiver causing noise and performance degradation
Solution Approach 1:
An asymmetrical baffle structure is introduced as an intermediary element between the transmitter and receiver. The baffle preferentially blocks stray radiation from the transmitter from reaching the receiver while allowing the main optical paths to remain unobstructed. This mediator structure resolves the contradiction by enabling compact integration while filtering out harmful stray radiation that would otherwise cause noise in the receiver.
Solution Approach 2:
The baffle is designed with an asymmetrical geometry that is optimized to block stray radiation paths from the transmitter to the receiver while maintaining clear paths for the intended optical signals. The asymmetrical shape allows selective blocking of harmful radiation based on its propagation direction, enabling effective noise reduction in the compact integrated package without compromising the main optical functionality.
2Object-affected harmful factors
If traditional symmetrical baffles are used to block stray radiation, then stray light blocking is achieved, but ancillary components cannot be mounted closely and device complexity increases
Solution Approach 1:
The asymmetrical baffle design eliminates the need for complex symmetrical structures by using a simplified single-sided configuration. This asymmetrical approach blocks stray radiation effectively while leaving sufficient space on one side for mounting ancillary components, thereby reducing overall packaging complexity compared to traditional symmetrical baffle designs that would require more intricate arrangements.
Solution Approach 2:
The baffle is positioned and shaped to provide localized blocking of stray radiation specifically in the critical paths from transmitter to receiver, while leaving other regions of the package open for ancillary component mounting. This localized approach to stray light blocking avoids the need for comprehensive symmetrical structures, reducing device complexity while maintaining effective radiation filtering where needed.
3Measurement precision
If all stray radiation is blocked to eliminate noise, then receiver signal quality is improved, but calibration capability for ToF measurements is lost
Solution Approach 1:
The asymmetrical baffle provides selective blocking of stray radiation, allowing different regions of the receiver to experience different levels of stray light. Specifically, a first region is protected from stray radiation to maintain high signal quality for normal measurements, while a second region receives controlled stray radiation that can be used for ToF calibration. This localized differentiation resolves the contradiction by enabling both noise reduction and calibration functionality simultaneously.
Solution Approach 2:
The baffle structure acts as a selective intermediary that mediates between the transmitter and different regions of the receiver. It blocks stray radiation paths to protected regions while allowing controlled stray light to reach calibration regions, thereby enabling the system to maintain both high measurement precision and calibration capability through spatially differentiated light management.
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 asymmetrical baffle design reduces noise while allowing controlled stray light for calibration, enhancing performance and flexibility in packaging, and enabling efficient operation of optical modules.
Implementation Method 1
An optical baffle is disposed asymmetrically relative to the transmit axis and has an asymmetrical shape configured to block preferentially stray radiation emitted from the optical transmitter toward the receive axis
Implementation Method 2
a transmission lens assembly, which is configured to direct the beam along a transmit axis toward a target
Implementation Method 3
an objective lens assembly, which is configured to focus the optical radiation that is reflected from the target along a receive axis onto the optical sensor
Data Source
Figure 1~2
Figure 3A~3B
Figure 4~5
AI summary
An optical device (20, 60, 80) includes a substrate (26) and an optical transmitter (21), which is mounted on the substrate and includes an optical emitter (22), which is configured to emit a beam of optical radiation, and a transmission lens assembly (30), which is configured to direct the beam along a transmit axis (31) toward a target. An optical receiver (23) is mounted on the substrate alongside the optical transmitter and includes an optical sensor (24) and an objective lens assembly (42), which is configured to focus the optical radiation that is reflected from the target along a receive axis (45) onto the optical sensor. An optical baffle (48, 50, 65) is disposed asymmetrically relative to the transmit axis and has an asymmetrical shape configured to block preferentially stray radiation emitted from the optical transmitter toward the receive axis.