Scanning Ophthalmoscope Illumination Control for Mirror Motion Deviations
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Solution Overview
Problem
Ophthalmic imaging scanners face challenges in ensuring that the eye is not exposed to radiation levels that exceed the maximum permissible exposure, necessitating real-time monitoring and safety mechanisms to prevent deviations in beam delivery.
Innovation Solution
An ophthalmic imaging instrument with a rotatable mirror and a rotary encoder that generates a signal indicative of its rotational motion, allowing a processor to detect deviations and generate control signals to reduce illumination, either by adjusting power or blocking the beam, thus maintaining safe exposure levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If real-time monitoring and safety mechanisms are implemented to prevent deviations in beam delivery, then patient safety is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where a rotary encoder continuously monitors the actual rotational position of the scanning mirror and provides real-time feedback to the control system. The processor compares the expected position (based on drive mechanism commands) with the actual position (from encoder feedback) and generates correction signals or safety alerts when deviations are detected, thereby ensuring patient safety through continuous monitoring without requiring complex manual intervention systems
Solution Approach 2:
The patent replaces complex mechanical safety monitoring systems with an electronic sensing and processing system. Instead of using multiple mechanical sensors and interlocks, the invention uses a rotary encoder (electronic position sensor) coupled with a processor to monitor mirror position electronically, simplifying the overall system architecture while maintaining high reliability
2Object-affected harmful factors
If the beam illumination is reduced in response to detected deviations, then harmful radiation exposure is prevented, but imaging quality may deteriorate
Solution Approach 1:
The patent applies preliminary anti-action by implementing safety thresholds and predictive monitoring. The system continuously monitors mirror position deviations and compares them against pre-established safety thresholds. When deviations approach critical levels, the system proactively reduces illumination or triggers safety protocols before harmful radiation exposure can occur, preventing damage before it happens rather than reacting after damage occurs
Solution Approach 2:
The patent implements a graduated response system where illumination reduction is applied partially rather than completely. Instead of immediately shutting off the beam upon any deviation, the system applies partial illumination reduction proportional to the severity of the deviation, maintaining sufficient imaging quality for diagnostic purposes while preventing harmful exposure levels. This allows the system to operate in a safe manner without completely sacrificing imaging functionality
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
Effectively limits exposure to safe radiation levels by detecting and responding to deviations in the rotational motion of the mirror, preventing potential eye damage.
Implementation Method 1
a rotary encoder coupled to the rotatable mirror so as to generate a signal indicative of a rotational motion of the rotatable mirror. The rotary encoder may comprise: an encoder wheel attached to the rotatable mirror so as to rotate with the rotatable mirror, the encoder wheel having markings for detecting a rotation of the encoder wheel; and a detector arranged to detect the markings on the encoder wheel as the encoder wheel rotates
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
An ophthalmic imaging instrument for imaging an eye of a subject, comprising: a light source arranged to emit a beam of light for imaging the eye; an optical system comprising a rotatable mirror and a drive mechanism arranged to drive the rotatable mirror to undergo a predetermined rotational motion to scan the beam of light across the eye; a rotary encoder coupled to the rotatable mirror so as to generate a signal indicative of a rotational motion of the rotatable mirror; and a processor arranged to detect when the rotational motion of the rotatable mirror indicated by the signal has deviated from the predetermined rotational motion and, in response to detecting that the rotational motion of the rotatable mirror has deviated from the predetermined rotational motion, generate a control signal to reduce an illumination of the eye by the beam of light.