Mirror Emissivity Target for Background-Resistant Temperature Measurement
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Solution Overview
Problem
Existing microlithographic projection exposure apparatuses face challenges in accurately measuring mirror temperatures due to interference from background radiation, which affects the imaging quality and operational control of the apparatus.
Innovation Solution
The mirror device incorporates a target with increased emissivity for infrared radiation, allowing the sensor unit to distinguish between infrared radiation emitted by the mirror body and background radiation, thereby improving temperature measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If infrared radiation is used to measure mirror temperature, then temperature information can be obtained, but background radiation from frame structure or housing interferes with measurement accuracy
Solution Approach 1:
The patent applies local quality by creating a target region on the mirror with different emissivity characteristics compared to the rest of the mirror surface. This target area has enhanced infrared emissivity to stand out from the background, allowing the sensor to distinguish the mirror's thermal radiation from background radiation sources. The local modification enables selective detection of the mirror's temperature without interference from surrounding structures.
Solution Approach 2:
The patent introduces an intermediary approach by using a target with increased emissivity as a mediator between the mirror body and the sensor. This target acts as an enhanced radiative interface that converts the mirror's thermal energy into detectable infrared signal with higher contrast against background radiation, effectively mediating the measurement process to overcome background interference.
2Measurement precision
If a target with increased emissivity is added to the mirror, then temperature measurement quality improves, but device complexity increases
Solution Approach 1:
The patent implements local quality by modifying only a specific region of the mirror surface rather than the entire mirror. The target area with enhanced emissivity is localized to a small portion of the mirror, allowing temperature measurement improvement without requiring complex modifications to the overall mirror structure or adding substantial components.
Solution Approach 2:
The patent applies the color changes principle by modifying the infrared radiative properties (analogous to optical color) of the target region. The target area has different emissivity characteristics that make it appear distinct in the infrared spectrum, enabling the sensor to identify and measure the mirror temperature with high accuracy while maintaining simple structural integration.
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 solution enhances the quality of temperature measurements by increasing the proportion of relevant infrared radiation relative to background radiation, enabling precise temperature control and adjustment of the projection exposure apparatus.
Implementation Method 1
The sensor unit is designed to detect infrared radiation given off by the mirror body in order to derive a temperature measurement value therefrom
Implementation Method 2
The mirror body comprises a target with an increased emissivity for infrared radiation. The increased emissivity results in an increase in the proportion of the relevant infrared radiation relative to the background radiation
Data Source
AI summary
A mirror device, for example for a microlithographic projection exposure system, comprises a mirror, a sensor unit and a control unit. The mirror comprises a mirror body and a reflective surface provided on the mirror body. The sensor unit is designed to detect infrared radiation given off by the mirror body in order to derive a temperature measurement value therefrom and to send the temperature measurement value to the control unit. The mirror comprises a target with an increased emissivity for infrared radiation. The disclosure also relates to a method for measuring the temperature of a mirror.