Applanation Tonometer Head Curved Surface Light Propagation
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Solution Overview
Problem
Current applanation tonometer heads face difficulties in intraocular pressure measurement due to weak light emission from ophthalmic dye, primarily caused by the shape of the end portion leading to poor illumination and interference from spurious light arcs that disturb vision.
Innovation Solution
A rotationally symmetrical applanation tonometer head with a portion having an external lateral surface inclined at an angle between 0° and 80°, allowing light to enter and propagate without reflection, and featuring semi-cylindrical or semi-elliptical prisms with inclined bases to improve illumination and reduce spurious light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the end portion of the tonometer head has a conventional shape, then the structure is simple, but the illumination of the corneal applanation surface is poor and spurious light arcs interfere with vision
Solution Approach 1:
The end portion of the tonometer head is designed with a curved external lateral surface instead of flat surfaces. This curvature allows light to propagate through the transparent material without reflection and without encountering surfaces of discontinuity, thereby improving illumination of the corneal applanation surface and eliminating spurious light arcs that would interfere with the physician's vision.
Solution Approach 2:
The patent changes the geometric parameters of the end portion by defining specific internal angles (between 0° and 80°) for the curved external lateral surface. This parameter optimization ensures that light enters the end portion and propagates to the corneal applanation surface without reflection, resolving the illumination problem while maintaining structural integrity.
2Measurement precision
If the prisms have conventional inclined surfaces, then they are effective for splitting light, but spurious light arcs are generated that disturb the physician's vision
Solution Approach 1:
The patent extracts or removes the problematic conventional inclined surfaces from the prism design. Instead of using traditional inclined surfaces that generate spurious light arcs, the invention uses curved surfaces that guide light without creating harmful reflections, thereby maintaining measurement precision while eliminating visual interference.
Solution Approach 2:
The patent converts the potentially harmful effect of light reflection into a beneficial outcome by designing curved surfaces that redirect light constructively. The curved external lateral surface of the end portion and the curved surfaces of the prisms work together to guide light to where it is needed (the corneal applanation surface and hemicorones) without creating spurious arcs that would disturb vision.
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
Enhances the illumination of the corneal applanation surface and minimizes spurious light arcs, resulting in improved visibility and accuracy of intraocular pressure measurements.
Implementation Method 1
a beam of light incident on the external lateral surface from the outside of the applanation head enters the second portion and propagates in the end portion to the flat corneal applanation surface without making the light beam be reflected
Implementation Method 2
two semi-cylindrical or semi-elliptical prisms, each having: a respective lower semicircular or semi-elliptical base integral with the second portion and having a nominal height at a center of the respective base; a respective upper base inclined with respect to the respective lower base by a respective internal angle
Implementation Method 3
two semi-cylindrical or semi-elliptical prisms
Data Source
Figure 1~2
Figure 3~4
Figure 5~6d
AI summary
A rotationaliy symmetrical head for an applanation tonometer has a portion bounded by a respective major base and a respective minor base and a respective external lateral surface L2 having at least one area inclined with respect to the base greater than a respective internal angle between 0° and 80°, This zone is configured so that a beam of light incident on it from the outside of the applanation head enters the second portion 3 and propagates through the end portion 2 to the flat corneal applanation surface without the light beam being reflected and without encountering surfaces of discontinuity of material.