Eye Optical System Depth of Field Measurement
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Solution Overview
Problem
Conventional methods for measuring the depth of field of eye optical systems are time-consuming and yield inaccurate results due to changes in the eye's characteristics over time, such as tear film evaporation and accommodation changes.
Innovation Solution
A device comprising a Badal system with a lens of positive optical power, a positioning apparatus to maintain the eye optical system at a focal plane, and a multi-vergency target providing multiple objects at uniform optical path differences, allowing for simultaneous viewing and reflection into the eye's field of view, enabling accurate depth of field measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional scanning techniques are used to measure depth of field, then the measurement can be performed with simple equipment, but the measurement time is excessive and accuracy deteriorates due to eye characteristic changes over time
Solution Approach 1:
The patent transitions from temporal scanning (viewing objects at different times) to spatial arrangement (viewing multiple objects simultaneously at different vergences). The multi-vergency target presents multiple test objects at different optical distances along the optical axis, allowing the eye to view all vergences simultaneously rather than sequentially, thereby eliminating time-related measurement errors.
Solution Approach 2:
The patent combines multiple test objects at different vergences into a single multi-vergency target that can be viewed simultaneously. This merging of multiple measurement targets into one unified structure allows the eye to assess depth of field across multiple focal points in a single viewing event, dramatically reducing measurement time.
2Productivity
If multiple test objects at different vergences are presented simultaneously, then measurement time is reduced, but device complexity increases due to Badal system and positioning apparatus
Solution Approach 1:
The Badal system acts as an intermediary optical mechanism that translates physical position changes into controlled vergence changes. By using the Badal system as a mediator, the patent can present multiple vergences through a single physical target structure, managing the complexity of presenting multiple test objects at different optical distances.
Solution Approach 2:
The Badal system serves multiple functions: it creates the multi-vergency target, controls the vergence of each object, and maintains the eye at a fixed focal plane. This multi-functionality reduces the need for separate mechanisms for each function, thereby managing overall device complexity while achieving high productivity.
3Ease of operation
If the eye is allowed to move or accommodate during measurement, then natural viewing conditions are maintained, but measurement accuracy deteriorates due to changes in optical path length
Solution Approach 1:
The Badal system creates an equipotential optical environment where the eye is maintained at a fixed focal plane while viewing objects at different vergences. This equipotential condition ensures that the optical path length from the eye to the focal plane remains constant, preventing accommodation changes while allowing comfortable viewing of multiple vergences.
Solution Approach 2:
The patent changes the vergence parameter of the test objects while keeping the eye's focal plane position constant. By using the Badal system to adjust object vergences rather than eye position, the patent maintains optical path length consistency while still presenting varying focal demands to the eye.
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 device provides efficient and accurate measurement of the depth of field by maintaining consistent optical path differences and angular resolution, reducing the impact of temporal changes in the eye's characteristics, thereby improving measurement precision and reducing practitioner and patient time consumption.
Implementation Method 1
a lens having positive optical power, a positioning apparatus adapted to maintain the eye optical system on the image side of the lens at a first focal plane of the lens
Implementation Method 2
the device further comprising reflective surfaces to reflect the plurality of objects into the field of view of the eye optical system
Data Source
AI summary
A device for measuring depth of field of an eye optical system that includes a lens Badal having positive optical power, a positioning apparatus adapted to maintain the eye optical system on the image side of the lens at a first focal plane of the lens and a multi-vergency target that provides a plurality of objects that are simultaneously viewable, through the lens, by the eye optical system.