Absorptive Perforated Disk for Stray-Light-Free Confocal Imaging
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Solution Overview
Problem
Existing perforated disks in optical imaging systems suffer from stray light reflections and geometric aberrations, leading to imaging errors and reduced transmission efficiency, which conventional methods like tilting or polarization optics cannot fully address.
Innovation Solution
A perforated disk made of an optically absorbing material with a high absorption coefficient (>98%) minimizes stray light by absorbing most incident light outside the openings, eliminating the need for tilting or polarization optics, and features a substrate with strategically arranged optical passages for improved light collection and imaging accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an optically transparent material with reflective coating is used for the perforated disk, then the disk can be manufactured with precise openings, but stray light reflections occur that overpower the useful light and cause imaging errors
Solution Approach 1:
The patent changes the optical parameter of the disk material from reflective (conventional) to highly absorptive (≥98% absorption coefficient). This parameter change eliminates stray light reflections by absorbing incident light instead of reflecting it, while maintaining precise opening geometry through controlled material deposition or selective removal processes.
Solution Approach 2:
The patent employs a composite structure consisting of an optically absorptive material substrate with precisely engineered openings. The composite nature combines the light-absorbing property of materials like black anodized aluminum or carbon-loaded plastics with precisely controlled aperture geometry, achieving both manufacturing precision and stray light elimination.
2Object-generated harmful factors
If the perforated disk is tilted in the optical beam path to reduce reflections, then stray light is coupled out of the beam path, but all optical elements must be tilted causing asymmetry and geometric aberrations
Solution Approach 1:
Instead of tilting the disk to redirect reflections away from the beam path (conventional approach), the patent converts the harmful reflection effect into a beneficial absorption effect. The disk surface is designed to absorb incident light directly, eliminating the need for tilting and the associated geometric aberrations while still achieving stray light reduction.
3Object-generated harmful factors
If polarization optics are used to reduce reflections from the perforated disk, then some stray light is suppressed, but the approach is limited because not all images are polarization-preserving
Solution Approach 1:
The patent changes the fundamental optical interaction parameter from polarization-based reflection suppression to absorption-based suppression. By using a material with ≥98% absorption coefficient, the system achieves reliable stray light reduction that is independent of the polarization properties of the imaged object, eliminating the limitations of polarization-based approaches.
4Use of energy by moving object
If an optically transparent material is used for the perforated disk, then the disk can transmit light, but geometric aberrations occur due to optical displacement and chromatic aberrations from dispersion
Solution Approach 1:
The patent changes the light interaction parameter from transmission (transparent materials) to absorption (highly absorptive materials). This eliminates chromatic aberrations and optical displacement effects inherent in transparent materials, while light selection is achieved through the pattern of openings rather than material transparency.
5Ease of manufacture
If a reflective coating is applied to the perforated disk, then the disk can be made from transparent material, but the reflective layer emits stray light that strikes the light detector
Solution Approach 1:
The patent changes the surface optical parameter from reflective to highly absorptive. Instead of applying a reflective coating to transparent material, the disk is manufactured from or coated with a material having ≥98% light absorption coefficient, eliminating stray light emission while maintaining manufacturability through standard coating or material selection processes.
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 solution significantly reduces stray light intensity, enhances imaging accuracy, and maintains high signal-to-noise ratio, enabling precise 3D surface topography measurement with reduced geometric and chromatic aberrations.
Implementation Method 1
The described perforated disk comprises an optically absorbing material having an absorption coefficient of at least 98%, wherein at least one recess is provided in the optically absorbing material, defining an optical passage through the perforated disk.
Data Source
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AI summary
A perforated disk (150) for selecting light for an optical imaging, in particular for an optical imaging in a confocal imaging system (100). The described perforated disk (150) has an optically absorbing material (170), which has an absorption coefficient of at least 98%, where in the optically absorbing material (170) at least one opening (172) is present, which defines an optical passage (172) through the perforated disk (150). Preferably, the optically absorbing material (170) contains carbon nanotubes. Furthermore, there is described a confocal optical imaging system (100) having such a perforated disk (150).