Monolithic Photodetector Array for High-Speed Trajectory Measurement
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Solution Overview
Problem
Existing methods for determining the flight trajectory of rapidly flying objects, such as target droplets in laser plasma sources, face challenges in accuracy and speed due to reaction and deflection effects, especially at high repetition rates, making precise prediction and control difficult.
Innovation Solution
A measuring arrangement featuring a photodetector arrangement with a monolithic construction and an imaging system that images flying objects onto photodetector cells, allowing for the measurement of transit instants across defined target lines, enabling accurate and prompt determination of flight trajectories at high repetition rates without the need for time-consuming image evaluation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-speed cameras are used to observe rapidly flying projectiles, then the flight trajectory can be captured visually, but the measurement speed and accuracy deteriorate at high repetition rates due to reaction and deflection effects
Solution Approach 1:
The photodetector array is divided into multiple individually addressable photodetector cells arranged in a monolithic construction, allowing selective reading of specific cells rather than requiring full-frame image capture. This segmentation enables rapid extraction of trajectory information from only the relevant detected positions, significantly reducing measurement time at high repetition rates while maintaining accuracy.
Solution Approach 2:
The patent replaces the mechanical/image-based capture system (high-speed camera) with an optical detection system using photodetector cells that directly convert light signals from the flying object into electrical signals. This substitution eliminates the need for mechanical shuttering and frame-by-frame image processing, enabling much faster measurement cycles capable of handling high repetition rates up to 100 kHz.
2Loss of information
If image evaluation is performed to determine flight trajectories, then comprehensive trajectory information can be obtained, but the process becomes time-consuming and increases data age
Solution Approach 1:
The system extracts only the essential trajectory information directly from the photodetector cell signals without performing comprehensive image evaluation. By taking out only the necessary data (detected position and transit instant from individual photodetector cells) rather than processing complete images, the system obtains sufficient trajectory information with minimal processing time, reducing data age to less than 10 µs.
Solution Approach 2:
The patent uses optical copying through the lens system to project the flying object's position directly onto the photodetector array, creating an optical map of position information. This optical copying eliminates the need for complex image capture and digital image evaluation, as the position information is directly transduced into electrical signals by the photodetector cells, enabling rapid trajectory determination.
3Productivity
If droplets are fed at high injection rates to meet light demand, then production efficiency increases, but reaction and deflection effects on subsequent droplets worsen trajectory predictability
Solution Approach 1:
The measuring arrangement provides real-time feedback on the actual flight trajectory and position of each droplet by detecting transit instants across defined target lines using the photodetector array. This feedback information can be used to adjust and optimize the injection timing and positioning for subsequent droplets, compensating for reaction and deflection effects and improving trajectory predictability even at high injection rates of 100 kHz.
Solution Approach 2:
The system measures and determines the flight trajectory of each droplet in advance before it reaches the interaction region, using the photodetector array to detect position and calculate trajectory parameters. This preliminary determination allows for predictive control and adjustment of subsequent droplet injection parameters, compensating for known reaction and deflection effects that occur at high repetition rates.
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 allows for precise and rapid determination and prediction of flight trajectories, reducing 'data age' to less than 10 µs, even at rates up to 100 kHz, and can be applied to various applications including EUV lithography and microscopic observations.
Implementation Method 1
at least one photodetector arrangement comprising a plurality of photodetector cells in a monolithic construction; wherein said photodetector arrangement is assigned exactly one imaging system
Data Source
Figure 1
Figure 2a~3
Figure 4a~4b
AI summary
The invention relates to a measuring arrangement for use when determining trajectories of flying objects, wherein the measuring arrangement comprises at least one photodetector arrangement (41 1, 412, 421, 422, 780, 785, 880, 980) comprising a plurality of photodetector cells in a monolithic construction, wherein said photodetector arrangement (41 1, 412, 421, 422, 780, 785, 880, 980) is assigned exactly one imaging system (700, 750, 800, 900), which, during the operation of the measuring arrangement, images in each case a flying object situated in an object plane (OP) of the imaging system onto the photodetector arrangement situated in an image plane (IP) of the imaging system, and a time measuring device for measuring transit instants, wherein each of said transit instants corresponds to an instant at which an image of a flying object, said image being generated in the image plane (IP) of the imaging system, in each case crosses a cell boundary between mutually adjacent photodetector cells in the photodetector arrangement (41 1, 412, 421, 422, 780, 785, 880, 980).