Slit Lamp Microscope Scheimpflug Correction for Focused Eye Imaging
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Solution Overview
Problem
Scheimpflug-type slit lamp microscopes face deviations from the Scheimpflug condition due to refractive index differences between the inside and outside of the subject's eye, causing disorder in optical system arrangement and requiring time-consuming scanning in multiple directions for focused imaging.
Innovation Solution
A slit lamp microscope design that aligns the subject plane, principal plane of the optical system, and light detecting surface to satisfy the Scheimpflug condition, incorporating a movement mechanism for parallel photography and image construction, and includes processors for three-dimensional image rendering and analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Scheimpflug principle is applied to arrange the optical system, then the image can be focused over the entire subject plane, but the refractive index differences cause deviation from the Scheimpflug condition and disorder in optical system arrangement
Solution Approach 1:
The patent applies parameter changes by adjusting the optical system arrangement parameters to compensate for refractive index differences. Specifically, the optical axis of the photographing system is set to form a predetermined angle with the optical axis of the illumination system, and the subject plane is positioned at a specific angle relative to the optical axis. These parameter adjustments ensure that the Scheimpflug condition is satisfied despite variations in refractive indices of different eye tissues.
2Measurement precision
If scanning in multiple directions is performed to achieve focused imaging, then the entire subject plane can be imaged, but the process becomes time-consuming
Solution Approach 1:
The patent applies preliminary action by pre-configuring the optical system according to the Scheimpflug principle before actual photographing. The subject plane, principal plane of the optical system, and light detecting surface are arranged to satisfy the Scheimpflug condition in advance. This preliminary arrangement eliminates the need for time-consuming scanning operations during image acquisition, as the system is already optimized for focused imaging across the entire subject plane.
3Measurement precision
If the optical system is arranged according to Scheimpflug principle, then the subject plane can be imaged in focus, but individual differences in eye tissue refractive indices cause variation in optical arrangement disorder
Solution Approach 1:
The patent applies dynamics by making the optical system arrangement adaptable to individual eye characteristics. The system allows for adjustment of the angle between the illumination optical axis and photographing optical axis, and the positioning of the subject plane, to accommodate variations in refractive indices caused by individual differences in corneal shapes and tissue characteristics. This dynamic adaptability ensures consistent imaging quality across different subjects.
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 focused imaging over the entire subject plane by compensating for refractive index differences, allowing efficient and accurate three-dimensional image acquisition and analysis.
Implementation Method 1
the light beam is refracted by the difference between the refractive indices inside and outside the subject's eye, thereby disordering the optical system arrangement
Data Source
AI summary
A slit lamp microscope according to some aspect examples includes an illumination system and photographing system. The illumination system projects slit light onto an anterior segment of a subject's eye. The photographing system includes an optical system and an image sensor. The optical system directs light from the anterior segment onto which the slit light is being projected. The image sensor includes a light detecting surface that receives the light directed by the optical system. Further, a subject plane, a principal plane of the optical system, and the light detecting surface are arranged so as to satisfy a Scheimpflug condition. Here, the subject plane includes a focal point of the illumination system in which a position of the focal point is shifted on account of a refractive index of a tissue of the anterior segment.