Apodization Optical System With Segmented Transmittance Elements
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Solution Overview
Problem
Existing optical systems fail to maintain a consistent apodization effect on-axis beam when the in-focus distance changes, leading to variations in the appearance of blurred images at the image center.
Innovation Solution
An optical system comprising multiple lens elements, where at least one moves during focusing, with a first optical element on the light incident side and a second optical element on the light emission side of the aperture diaphragm, both having transmittance distributions that satisfy specific conditional expressions to minimize changes in the apodization effect due to in-focus distance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an optical element having transmittance distribution is provided only at the object side end of the optical system, then the apodization effect can be provided to the off-axis beam, but the apodization effect on the on-axis beam changes significantly when the in-focus distance changes
Solution Approach 1:
The optical system is divided into two segments: an object-side optical element and an image-side optical element, both having transmittance distribution. This segmentation allows each element to contribute to the overall apodization effect, with the object-side element primarily affecting off-axis beams and the image-side element primarily affecting on-axis beams, thereby maintaining consistent apodization across different focus distances
Solution Approach 2:
Different regions of the optical system are assigned different transmittance characteristics. The object-side optical element has transmittance distribution optimized for off-axis beams (Te1/T1 ≥ 0.6), while the image-side optical element has transmittance distribution optimized for on-axis beams (Te2/T2 ≤ 0.4). This local quality differentiation ensures that each region contributes appropriately to maintaining apodization consistency across the entire focus range
2Reliability
If the transmittance of the first optical element at the marginal ray position is too low, then the apodization effect is enhanced, but the light quantity at the center of the image becomes insufficient
Solution Approach 1:
The apodization function is segmented between two optical elements. The object-side element provides moderate apodization (Te1/T1 ≥ 0.6) to preserve central light quantity, while the image-side element provides stronger apodization (Te2/T2 ≤ 0.4) to ensure consistency. This segmentation allows the system to achieve both sufficient central illumination and consistent apodization effect
Solution Approach 2:
The transmittance parameters of the two optical elements are optimized within specific ranges (Te1/T1 ≥ 0.6 and Te2/T2 ≤ 0.4) to balance the apodization effect with light quantity distribution. By controlling these parameters, the system achieves optimal performance where the apodization effect remains consistent without excessively reducing the light quantity at the image center
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 solution effectively reduces changes in the apodization effect caused by in-focus distance changes, ensuring consistent light quantity distribution and minimizing asymmetrical light quantity issues, thereby maintaining image quality across different focus distances.
Implementation Method 1
Such light quantity distribution is achieved by an apodization effect. An apodization effect is obtained by using an optical element in which transmittance decreases as the distance from an optical axis increases.
Data Source
AI summary
An optical system includes an aperture diaphragm, a first optical element disposed on a light incident side of the aperture diaphragm, and a second optical element disposed on a light emission side of the aperture diaphragm. Transmittance distribution of the first optical element satisfies a predetermined conditional expression. Transmittance distribution of the second optical element satisfies a predetermined conditional expression.