Beam Propagation Camera With Diffractive Multi-Focus Beam Splitting

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Solution Overview

Problem

Current beam propagation measurement systems face challenges in accurately measuring the position of droplets and tracking infrared radiation in laser plasma sources due to the low intensity of reflected radiation, making precise high-precision adjustments difficult.

Innovation Solution

A beam propagation camera with a beam-splitting optical arrangement that splits the light beam into multiple partial beams using a diffractive structure decentered with respect to the optical axis, allowing for simultaneous recording of beam sections and improved focus offset, enabling precise analysis even under low-intensity conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional beam propagation measurement systems are used to measure droplet position and track infrared radiation, then the system can perform basic measurements, but the measurement precision deteriorates due to low intensity of reflected radiation

Engineering Contradiction:
Improvedroplet position measurement precisionVSAvoidreflected radiation intensity
Core Design Contradiction:
Measurement precisionVSIllumination intensity

Solution Approach 1:

The incident beam is segmented into multiple partial beams (at least three) with different focus offsets using a beam-splitting optical arrangement. This segmentation allows simultaneous measurement at multiple focus positions, improving measurement precision by capturing beam propagation characteristics across different focal planes, which is particularly beneficial when reflected radiation intensity is low.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention extends the measurement from a single focal plane to multiple focal planes by introducing focus offsets along the optical axis. This dimensional extension allows the system to measure beam parameters at different depths, effectively utilizing the third dimension (longitudinal focus position) to compensate for low signal intensity at any single plane.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If conventional single-focus measurement systems are used, then the device complexity is low, but the measurement precision deteriorates due to inability to capture beam propagation at multiple focus positions

Engineering Contradiction:
Improvebeam propagation measurement precisionVSAvoidoptical arrangement complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Multiple measurement functions (measuring beam parameters at different focus positions) are merged into a single optical arrangement. The beam-splitting optical arrangement simultaneously generates multiple partial beams with different focus offsets, allowing the system to perform multi-plane measurements without requiring separate measurement systems for each focal plane.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The beam-splitting optical arrangement serves multiple functions: it splits the incident beam, creates multiple partial beams with different focus offsets, and directs them to the sensor arrangement. This multi-functional component reduces the need for separate specialized devices, balancing enhanced measurement precision with controlled device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Manufacturing precision

If the beam is measured at a single focus position, then the measurement system is simpler, but the accuracy of focus position determination deteriorates

Engineering Contradiction:
Improvefocus position accuracyVSAvoidsensor arrangement complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The sensor arrangement receives segmented partial beams, each corresponding to a different focus position. By analyzing the spatial distribution and intensity of these segmented beams at their respective focus offsets, the system can accurately determine the actual focus position through comparison and correlation algorithms, achieving high precision without requiring a single complex high-resolution sensor.

Inventive Principle:
Principle #1Segmentation

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 solution allows for precise measurement of beam parameters and focus position, enhancing the accuracy and precision of droplet positioning and infrared radiation tracking in laser plasma sources.

Implementation Method 1

a beam-splitting optical arrangement which splits a beam incident on the beam-splitting optical arrangement along an optical axis of the beam propagation camera during operation into seven partial beams comprising the -3rd to +3rd diffraction order; and the beam-splitting optical arrangement comprises a diffractive structure

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

the beam-splitting optical arrangement comprises a diffractive structure and a refractive optical element

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP3100011B9Beam propagation camera and method for light beam analysis
Publication Date: 2021.03.24 CARL ZEISS SMT GMBH
  • EP3100011B9 patent drawingFigure 1
  • EP3100011B9 patent drawingFigure 2a~2b
  • EP3100011B9 patent drawingFigure 2c

AI summary

The invention relates to a beam propagation camera and a method for light beam analysis. A beam propagation camera according to the invention comprises at least one beam-splitting optical arrangement (240) which splits a beam impinging on the beam-splitting optical arrangement along an optical axis (OA) of the beam propagation camera during operation into a plurality of partial beams, and a sensor arrangement (250) for detecting said partial beams, wherein the beam-splitting optical arrangement (240) has a diffractive structure (241), and wherein said diffractive structure (241) is designed in such a way that at least two of the partial beams on the sensor arrangement (250) are spatially separated from one another and have a focus offset in a longitudinal direction relative to the optical axis (OA).