Aspherical Diffractive Optical System for Slit Curvature Correction
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Solution Overview
Problem
Existing optical systems for imaging apparatuses in industrial and medical fields fail to effectively correct curvature of field at slits, leading to potential shielding of light beams and reduced imaging accuracy.
Innovation Solution
An optical system comprising a front group with aspherical surfaces and a rear group with a diffractive surface, where the light-shielding member has an elongated opening, allowing for the formation of an intermediate image perpendicular to the readout direction and splitting light beams at different wavelengths, thereby correcting curvature of field and improving imaging precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a cylindrical mirror is used to focus a light beam at a slit, then the light beam can be focused, but curvature of field is generated at the slit causing light beam shielding
Solution Approach 1:
The patent changes the curvature radius parameter of the aspherical surface in the second section, making it differ between on-axis and off-axis positions. This parameter modification enables the optical system to correct the curvature of field while maintaining the focusing capability, thereby preventing light beam shielding and improving imaging accuracy.
Solution Approach 2:
The patent employs an aspherical surface instead of a simple spherical or cylindrical surface. The aspherical surface has different curvature radii at different positions (on-axis versus off-axis), which allows it to correct the curvature of field generated by the cylindrical mirror while still focusing the light beam properly at the slit.
2Device complexity
If the curvature of field is not corrected at the slit, then the optical system structure remains simple, but light beams may be shielded and imaging precision decreases
Solution Approach 1:
The patent combines the focusing function of the cylindrical mirror with the curvature correction function of the aspherical surface into a single integrated optical system. The aspherical surface performs dual functions: maintaining the light beam focusing capability while simultaneously correcting the curvature of field, thus improving imaging precision without significantly increasing structural 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
The optical system successfully corrects curvature of field, prevents light beam shielding, and enhances imaging accuracy by focusing light beams at different wavelengths on distinct locations, increasing the angle of view and precision of image formation.
Implementation Method 1
the rear group has a diffractive surface that splits a light beam that passes through the opening into light beams at different wavelengths in the second section and focuses the light beams on different locations in the second section
Implementation Method 2
the front group has an aspherical surface that does not image the object at the opening in a first section parallel to the first direction and forms an intermediate image of the object at the opening in a second section perpendicular to the first direction
Data Source
AI summary
Optical system includes front group, light-shielding member, and rear group that are arranged from object side toward image side. The light-shielding member is provided with opening elongated in first direction. The front group has aspherical surface, does not image the object at the opening in first section parallel to the first direction, and forms intermediate image of the object at the opening in second section perpendicular to the first direction. The rear group has diffractive surface that splits light beam that passes through the opening into light beams at different wavelengths in the second section and focuses the light beams on different locations in the second section. The curvature radius of the aspherical surface in the second section at on-axis position in the first direction differs from that at outermost off-axis position in the first direction.