DUV-UV Refractive Spectroscopic Optical System for Vertical Illumination
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Solution Overview
Problem
Existing spectroscopic optical systems face challenges in achieving wide-range color correction across deep ultraviolet to ultraviolet wavelengths (190 to 400 nm) while maintaining vertical illumination, which is disrupted by sample surface movement during continuous scanning, and suffer from uneven brightness due to interference in refractive optical systems.
Innovation Solution
A spectroscopic optical system using only refractive lenses, with a configuration including an illumination optical system and a detection optical system, where the object-side and image-side lens systems are color corrected over the 190 to 400 nm range, and the working distance of each lens is set to less than 10.0 mm to minimize color shift and interference, ensuring vertical illumination to reduce displacement and maintain even brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a reflective optical system is used for color correction, then wide-range color correction is achieved, but vertical illumination cannot be maintained and sample surface displacement occurs during scanning
Solution Approach 1:
The patent replaces the reflective optical system with a refractive optical system consisting of multiple lenses (first lens, second lens, third lens) to achieve color correction. This substitution eliminates the need for oblique illumination while maintaining vertical illumination stability during sample scanning, thereby resolving the contradiction between color correction capability and illumination stability.
2Ease of operation
If a refractive-diffractive optical system is used, then vertical illumination is maintained, but color correction is limited to only two wavelengths
Solution Approach 1:
The patent divides the optical system into multiple segmented lens components (first lens, second lens, third lens) with different optical properties. Each lens contributes to correcting chromatic aberration at different wavelengths, enabling wide-range color correction across the visible spectrum while maintaining vertical illumination stability.
Solution Approach 2:
The patent employs a composite lens system where the first lens, second lens, and third lens are made of different optical materials with specific refractive indices and dispersion characteristics. This composite approach enables simultaneous correction of chromatic aberration across multiple wavelengths while maintaining the vertical illumination path.
3Strength
If doublets are attached using UV curing agent, then lens assembly is secured, but interference causes uneven brightness in the ultraviolet region
Solution Approach 1:
The patent extracts and eliminates the problematic UV curing agent from the lens assembly process. By removing this intermediary substance that causes interference and uneven brightness, the system achieves both secure lens attachment and uniform illumination across the ultraviolet region without compromising attachment strength.
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 configuration enables high-speed, accurate spectroscopic measurement with reduced displacement and interference, achieving effective color correction and precise film thickness measurement across the DUV-UV range.
Implementation Method 1
an object-side objective lens system and an image-side focusing lens system which are color corrected in a broad range of wavelengths from 190 to 400 nm and are formed by only refractive lenses
Implementation Method 2
it has been found that when the air space D between two lenses is small, uneven brightness (irregularity in the amount of light) occurs due to interference
Data Source
AI summary
Disclosed are a spectroscopic optical system and a spectrometer both enabling vertical illumination by means of an optical system using only refractive lenses and enabling wide-band color correction in the DUV-UV (190 to 400 nm) range. The spectroscopic optical system and spectrometer each comprise a light source (100), a folding mirror (110), a field stop (120), an object-side focusing lens system (130) for focusing light onto a sample, an image-side focusing lens (140) disposed on the image forming plane of the object-side focusing lens system, and a spectroscope (150) for dispersing regularly reflected light from the sample. The object-side focusing lens system (130) and the image-side focusing lens system (140) are each a spectroscopic optical system corrected with respect to color in a broad band of wavelength from 190 to 400 nm and configured from only refractive lenses enabling vertical illumination. The working distance (WD) of each lens is set shorter than a predetermined distance, and the doublet interval (D) is set longer than a predetermined distance.