Endoscope Light Source Apparatus with Reflected Light Detection
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Solution Overview
Problem
Endoscope light source apparatuses using semiconductor laser diodes face challenges in accurately detecting illumination light due to the limited dynamic range of light receiving devices, which affects the stability of light output, especially when the light emitting device generates heat and changes light intensity based on temperature.
Innovation Solution
The light source apparatus employs an optical fiber, a ferrule with a through-hole, a holder with a reflecting surface, and an optical sensor positioned to receive second reflected light, allowing for accurate detection of illumination light by reflecting the emission light twice before it reaches the sensor, thereby reducing the light intensity within the sensor's dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light receiving device is used to detect illumination light from a semiconductor laser diode, then real-time light amount detection is enabled, but the limited dynamic range of the light receiving device prevents accurate detection due to the large amount of illumination light
Solution Approach 1:
A beam splitter is introduced as an intermediary component between the illumination light path and the light receiving device. The beam splitter divides the illumination light into a reference light portion and a detection light portion, enabling the light receiving device to detect light amounts within its dynamic range while still monitoring the overall illumination output.
Solution Approach 2:
The illumination light is segmented into multiple portions using the beam splitter - a reference light portion that maintains the original light characteristics and a detection light portion that is suitable for light receiving device measurement. This segmentation allows accurate detection without requiring the light receiving device to handle the full intensity range.
2Illumination intensity
If the amount of illumination light is increased to ensure sufficient lighting for the endoscope, then adequate image brightness is achieved, but the light intensity exceeds the dynamic range of the light receiving device
Solution Approach 1:
The beam splitter acts as a mediator that allows high-intensity illumination light to pass through to the endoscope while simultaneously directing a reduced-intensity portion to the light receiving device for accurate detection within its dynamic range.
Solution Approach 2:
Different portions of the illumination light are treated differently - the main illumination path maintains high intensity for adequate lighting, while the detection path receives a divided, lower-intensity portion suitable for precise measurement by the light receiving device.
3Measurement precision
If the arrangement position of the light receiving device is changed to optimize detection, then detection angle may be improved, but the absolute value of received light changes largely affecting measurement consistency
Solution Approach 1:
The light receiving device provides real-time feedback on the light amount detected from the reference light portion. This feedback is used by the control unit to adjust the drive signal to the semiconductor laser diode, maintaining consistent illumination output despite variations in device positioning or environmental conditions.
Solution Approach 2:
The system uses a portion of its own illumination light (reference light) to monitor and regulate its performance. By detecting the light amount from the reference portion and using this information to control the light source, the system achieves self-regulation and maintains measurement consistency.
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 enables precise detection and control of illumination light, ensuring consistent brightness for endoscope images, even when using semiconductor light emitting devices, by adjusting the drive signal based on the optical sensor's output, thus maintaining appropriate light levels within the sensor's dynamic range.
Implementation Method 1
a holder having a reflecting surface configured to reflect first reflected light to thereby emit second reflected light, the first reflected light being the emission light reflected on the fiber end face
Data Source
AI summary
A light source apparatus for an endoscope includes an optical fiber that guides emission light emitted from a light source and is incident on a fiber end face, a ferrule having a ferrule end face having a through-hole in which the optical fiber is inserted, a holder to which the ferrule is fixed, the holder having a reflecting surface that reflects first reflected light to thereby emit second reflected light, the first reflected light being the emission light reflected on the fiber end face, and an optical sensor that receives the second reflected light disposed between the light source and the fiber end face and in a region facing the reflecting surface through an optical axis.