Adjustable Lens Perimeter for Consistent Stimulus Light Spot
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Solution Overview
Problem
Existing perimetry devices face challenges in maintaining consistent stimulus light spot size and brightness across different screen locations due to varying optical path lengths, which requires complex compensation optics and can introduce noise affecting examination accuracy.
Innovation Solution
The perimeter incorporates adjustable projection optics with a lens having an adjustable focal length, controlled by a control unit to compensate for varying path lengths, ensuring consistent stimulus light spot size and brightness across all screen locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If displaceable mirrors are used for path length correction, then the stimulus light spot focus can be compensated, but the mechanical complexity increases and actuating mirrors creates noise that affects examination accuracy
Solution Approach 1:
The patent replaces the mechanical displacement mirror system with an adjustable lens that can be rotated to change its focal length. This optical substitution eliminates mechanical movement in the compensation path, thereby reducing mechanical complexity and eliminating the noise generated by moving mirrors while still achieving path length correction for the stimulus light spot.
Solution Approach 2:
The patent changes the focal length parameter of the adjustable lens to compensate for varying optical path lengths. By rotating the lens to different focal length positions, the system adapts to different screen locations without requiring mechanical displacement of mirrors, thus solving the contradiction between precision and complexity.
2Manufacturing precision
If displaceable mirrors are used for path length correction, then the stimulus light spot focus can be compensated, but the noise from actuating mirrors alerts the patient and reduces examination accuracy
Solution Approach 1:
The patent replaces the mechanical displacement mirror system with an adjustable lens that can be rotated to change its focal length. This optical substitution eliminates mechanical movement in the compensation path, thereby reducing mechanical complexity and eliminating the noise generated by moving mirrors while still achieving path length correction for the stimulus light spot.
3Adaptability or versatility
If the optical path length varies with screen location, then the perimeter can cover a wide field of view, but the stimulus light spot size and brightness become inconsistent across different locations
Solution Approach 1:
The patent employs a dynamically adjustable lens whose focal length can be changed during operation. The lens is rotated to different positions corresponding to different focal lengths, allowing the system to adapt to varying optical path lengths at different screen locations while maintaining consistent stimulus light spot size and brightness across the entire field of view.
Solution Approach 2:
The patent changes the focal length parameter of the adjustable lens to compensate for varying optical path lengths. By rotating the lens to different focal length positions, the system adapts to different screen locations without requiring mechanical displacement of mirrors, thus solving the contradiction between precision and complexity.
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
This solution allows for simple and effective correction of stimulus light spot size, reducing mechanical complexity and noise, thereby enhancing the accuracy and reliability of visual field examinations.
Implementation Method 1
the projection optics comprises an adjustable lens with adjustable focal length. This lens can be used to correct the focus of the stimulus light spot quickly and easily, and it may be controlled as a function of the path length of the light from the light source to the screen
Implementation Method 2
the projection optics comprises a projection lens element arranged coaxially with and at a distance from the adjustable lens. This lens element can support the imaging operation of the adjustable lens. It advantageously has a fixed focal length
Implementation Method 3
An adjustable deflector: The adjustable deflector is adapted to deflect the light in order to generate the stimulus light spot at a plurality of selectable coordinates on the screen
Data Source
AI summary
The perimeter includes a screen, a light source assembly, projection optics, and an adjustable beam deflector. The projection optics includes an adjustable lens having a focal length that can be changed by the control unit of the device. The projection optics further includes a projection lens element. The focal length of the adjustable lens is being changed as a function of the location of the stimulus light spot, thereby compensating for the location-dependent length of the optical path from the projection optics to the screen. The distance between the projection lens element and the adjustable lens is equal to the focal length of the projection lens element, which makes the spot size independent on the location.