Tear Film Imaging Optics for Automatic Eye Alignment
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Solution Overview
Problem
Existing tear film photographing devices face challenges in implementing a position detection and automatic alignment function due to space limitations and difficulties in adjusting optical components, particularly when optical paths are folded, leading to increased device size and complexity.
Innovation Solution
A tear film photographing device with a first optical system for capturing interference fringes and a second optical system for wider anterior eye portion imaging, combined with positional deviation detection using multiple light sources and sensors, allows for automatic alignment without increasing device size by adjusting optical relationships and calculating positional deviations in X, Y, and Z directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a detector and LED are arranged on the back side of an objective lens to implement position detection and automatic alignment, then the position detection function and automatic alignment function are achieved, but the device size increases and space limitations are violated
Solution Approach 1:
The patent combines the tear film imaging optical system and the position detection optical system into a shared optical path. The imaging lens serves dual purposes: capturing tear film images and detecting eye position through Purkinje images. This merging eliminates the need for separate detectors and LEDs on the back side of the lens, thereby maintaining compact device size while achieving automatic alignment functionality.
Solution Approach 2:
The imaging lens is designed to perform multiple functions simultaneously: it acts as both the imaging lens for tear film capture and the objective lens for position detection. By making the lens universal, the patent avoids adding extra optical components that would increase device volume, thus resolving the contradiction between automation and device size.
2Extent of automation
If the optical paths of the LED and detector are folded on the back side of the objective lens, then the position detection function is implemented, but the adjustment of LED and detector positions becomes more difficult due to positional variations and angular variations
Solution Approach 1:
The patent merges the detection optical path with the imaging optical path, eliminating separate folded optical paths for LEDs and detectors. By using the imaging lens itself for detection purposes and capturing Purkinje images along with tear film images, the system removes the complexity of folded optical paths and associated alignment difficulties, thereby improving ease of operation.
3Measurement precision
If the photographing range of the second photographing unit is made wider than the first photographing unit, then the positional deviation detection accuracy is improved, but the optical system complexity increases
Solution Approach 1:
The patent combines both imaging functions (narrow-range tear film imaging and wide-range position detection imaging) into a single optical system using one imaging lens. The imaging lens captures both types of images simultaneously or sequentially, eliminating the need for separate optical systems with different focal lengths. This merging approach achieves the desired measurement precision while avoiding the complexity of multiple optical systems.
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 precise and efficient automatic alignment of the device with the eye under examination, facilitating clear tear film imaging without enlarging the device, thereby improving dry eye examination capabilities.
Implementation Method 1
a first photographing unit that receives the first light reflected by the tear film of the eye under examination and passing through the objective lens and photographs the interference fringes formed on the tear film
Implementation Method 2
a second light reflection unit that is disposed on an optical path of the first optical system and selectively reflects the second light reflected by a corneal surface of the eye under examination and passing through the objective lens
Data Source
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Figure 3(a)~3(b)
Figure 4
AI summary
In order to provide a tear film photographing device capable of implementing a position detection function for an eye under examination and an automatic alignment function, the tear film photographing device includes: a first optical system that includes an objective lens that is disposed so as to face the eye under examination, a first illumination unit that irradiates the eye under examination with first light through the objective lens, and a first photographing unit that receives the first light reflected by a tear film of the eye under examination and passing through the objective lens and photographs interference fringes formed on the tear film; a second optical system that includes a second illumination unit that irradiates the eye under examination with second light, a second light reflection unit that is disposed on an optical path of the first optical system and selectively reflects the second light reflected by a corneal surface of the eye under examination and passing through the objective lens, and a second photographing unit that receives the second light through the second light reflection unit and photographs an anterior eye portion of the eye under examination, the second optical system adjusting a positional relationship between respective optical components such that the second photographing unit can photograph a wider range than that of the first photographing unit; and a positional deviation amount calculation unit that calculates a positional deviation amount from a proper position of the first optical system with respect to the eye under examination based on an image of the anterior eye portion obtained by the second optical system.