Wavefront Aberration Detection Using Planar Mirror
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Solution Overview
Problem
Existing methods for detecting wavefront aberration of objective lenses are limited by the machining precision and cost of spherical mirrors, restricting the range of detectable numerical apertures (NAs) and requiring high-precision, customized mirrors.
Innovation Solution
A wavefront detection apparatus using a planar mirror positioned at the focal point of an objective lens, with a planar mirror adjusting mechanism to control the mirror's position and tilt, allowing for the emission and detection of test wavefronts to derive wavefront aberration using Zernike or Legendre polynomials, reducing the influence of machining errors and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a spherical mirror is used for wavefront detection, then the detection method is established, but the machining precision requirements and cost increase significantly for high-NA objectives
Solution Approach 1:
The patent replaces the expensive, high-precision spherical mirror with a low-cost planar mirror. The planar mirror has much lower machining precision requirements and can be a standard commercial product, eliminating the need for costly customized high-precision spherical mirrors while maintaining detection accuracy through the specific optical path design
Solution Approach 2:
The patent changes the fundamental parameter of the mirror from spherical to planar, which fundamentally alters the optical path requirements. This parameter change allows the use of low-precision planar mirrors instead of high-precision spherical mirrors, resolving the manufacturing precision contradiction
2Adaptability or versatility
If a spherical mirror with minimum f′/D of 0.65 is used, then the detection setup is feasible, but the detectable NA range is limited to 0.77 and above
Solution Approach 1:
The patent uses a standard planar mirror that is widely available and inexpensive, replacing the specialized spherical mirror that limits NA detection range. This allows detection of high-NA objectives (NA>0.9) that were previously inaccessible with commercial spherical mirrors
Solution Approach 2:
The planar mirror serves multiple functions: it reflects the wavefront, defines the focal point position, and works with various NA ranges. This universal component replaces the specialized spherical mirror, expanding the detectable NA range beyond the 0.77 limitation
3Measurement precision
If a customized high-NA spherical standard mirror is used, then detection accuracy for NA>0.9 objectives is achieved, but the cost increases significantly
Solution Approach 1:
The patent replaces the expensive customized spherical mirror with an inexpensive planar mirror. The planar mirror can be a standard commercial product with low machining costs, eliminating the need for expensive customized high-NA spherical mirrors while maintaining detection accuracy through the optimized optical path
Solution Approach 2:
The patent creates an equivalent detection capability using a planar mirror that copies the functional role of the spherical mirror but with much lower cost. The planar mirror performs the necessary wavefront reflection and focal point definition functions without requiring the expensive spherical geometry
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 approach lowers detection costs and expands the range of detectable NAs, minimizing the impact of machining errors on accuracy, while achieving precise wavefront aberration measurement with a margin of error less than 10%.
Implementation Method 1
a planar mirror is used for reflecting a wavefront at a focal point
Data Source
AI summary
Apparatus and method for detecting wavefront aberration of an objective lens, comprising a wavefront detection system, a planar mirror, and a planar mirror adjusting mechanism; the objective lens is placed between planar mirror and wavefront detection system; planar mirror is positioned at focal point of the objective lens. A test wavefront emitted by wavefront detection system passes through the objective lens, gets reflected by the planar mirror, and t passes through the objective lens again; the wavefront detection system receives and detects the test wavefront to derive a phase distribution thereof; an angle of the planar mirror tilts at is adjusted to obtain different return wavefronts; a polynomial for expressing wavefront aberration is selected, and expressions corresponding to all the return wavefronts are calculated; result of fitting the wavefront aberration of the objective lens when expressed by the selected polynomial is derived through fitting with the polynomial.