Measuring Endoscope Using Low Coherence Light for Constricted Pore Profile
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Solution Overview
Problem
Contact probes are ineffective in accurately measuring the surface profile of small, constricted pores due to difficulty in making contact with the inner walls, especially when the inner diameter increases in depth.
Innovation Solution
A measuring endoscope apparatus utilizing low coherence light and a single optical fiber to form interference patterns, allowing precise measurement of distances by adjusting optical path lengths and using polarizing beam splitters to ensure identical influence on both low coherence lights, enabling accurate surface roughness measurement of observation objects, including those with small diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a contact probe is used to measure surface profile, then measurement can be performed on surfaces with constant cross-section, but the probe cannot make contact with inner walls of pores with constricted diameters
Solution Approach 1:
The patent replaces the mechanical contact probe with an optical measurement system using a laser beam. The laser beam can penetrate through the constricted entrance of pores and illuminate the inner walls without requiring physical contact, thereby enabling measurement of pores with varying cross-sectional areas that cannot be accessed by contact probes.
Solution Approach 2:
The patent transitions from one-dimensional contact measurement to two-dimensional optical field measurement. By using a laser beam that can be focused and scanned across the pore interior, the system captures surface profile information from multiple dimensions, allowing accurate measurement of complex pore geometries including constricted diameters and varying cross-sections.
2Ease of operation
If the inner diameter of a pore is small at the entrance and increases in depth, then the pore can be accessed by a small probe, but the probe cannot make contact with the inner wall at the bottom
Solution Approach 1:
The patent substitutes the mechanical contact-based measurement with optical illumination and detection. The laser beam can be focused through the constricted entrance and scanned across the inner walls of the pore, enabling non-contact measurement of the bottom inner wall that is inaccessible to contact probes.
Solution Approach 2:
The patent employs dynamic scanning of the laser beam across the pore interior. By moving the beam position and adjusting the focus, the system can adapt to the varying geometry of the pore, scanning from the constricted entrance through to the bottom inner wall, thereby capturing measurement data from all accessible surfaces.
3Length of moving object
If a single optical fiber is used to transmit low coherence light, then the apparatus can be miniaturized for endoscopic measurement, but bending or orienting the fiber may affect measurement accuracy
Solution Approach 1:
The patent incorporates a feedback mechanism that continuously monitors the interference pattern quality and adjusts the optical path length accordingly. When the fiber is bent or reoriented, the system detects changes in the interference fringes and automatically compensates by adjusting the path length, thereby maintaining measurement accuracy despite fiber position variations.
Solution Approach 2:
The patent dynamically adjusts the optical path length parameter to compensate for fiber bending and reorientation. By changing the path length in response to detected variations, the system maintains the conditions necessary for accurate interference-based measurement, thereby decoupling the measurement precision from the fiber physical state.
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
Enables accurate measurement of surface profiles and roughness by forming interference fringes on an image detector, maintaining measurement accuracy even when the optical fiber is bent or oriented differently, effectively addressing the limitations of contact probes in measuring small, constricted spaces.
Implementation Method 1
a light source unit that is provided with a low coherence light source that emits low coherence light, a probe that illuminates an observation object with the low coherence light emitted from the light source unit and that collects the light reflected by the observation object, and a single optical fiber that optically connects the light source unit and the probe
Implementation Method 2
an optical path length adjustment part that adjusts the optical path length of the first low coherence light
Implementation Method 3
using polarizing beam splitters to ensure identical influence on both low coherence lights
Implementation Method 4
a lens (such as a gradient index lens) that conjugates a measuring surface position to an image surface at which an image detector is positioned
Data Source
AI summary
A measuring endoscope apparatus is disclosed having a light source unit that emits low coherence light, a probe that illuminates the observation object with the low coherence light and that collects light reflected by the observation object, and a single optical fiber that optically connects the light source unit and the probe. The light source unit includes a first low coherence light splitting part and an optical path length adjustment part. The probe includes a second low coherence light splitting part, a low coherence light multiplexing part, a lens that forms images using light returned from the observation object and an image detector that captures interference patterns and/or images using light reflected by the observation object. By using the low coherence light, surface conditions, such as roughness, can be accurately measured.