Diffractive Beam Propagation Camera for Weak Light Analysis
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Solution Overview
Problem
Existing beam propagation cameras face challenges in accurately analyzing light beams with weak intensity, particularly in laser plasma sources, due to the low intensity of reflected infrared radiation, which complicates precise droplet positioning and laser beam adjustment.
Innovation Solution
A beam propagation camera employing a diffractive structure for beam splitting, creating spatially separated sub-beams with longitudinal and lateral focus offsets, allowing for simultaneous recording and improved analysis of beam properties, even with weak light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional beam propagation camera is used to detect reflected infrared radiation from target droplets, then the system can provide beam analysis capability, but the measurement precision deteriorates due to the weak intensity of the reflected radiation
Solution Approach 1:
The patent divides the incident beam into multiple sub-beams using a diffractive optical element, creating several spatially separated beam paths. This segmentation allows the system to detect multiple diffraction orders simultaneously, each providing information about the droplet position, thereby improving measurement precision despite weak signal intensity
Solution Approach 2:
The patent introduces a longitudinal focus offset between different sub-beams in addition to lateral separation. This adds a depth dimension to the beam splitting, enabling the system to capture focus information at different planes simultaneously, which enhances the ability to determine droplet position and beam focus characteristics under low light conditions
2Measurement precision
If the beam is split into multiple sub-beams with focus offset, then the analysis of beam properties is improved, but the device complexity increases due to the diffractive structure design
Solution Approach 1:
The diffractive optical element serves multiple functions simultaneously: it splits the incident beam into multiple sub-beams, provides lateral spatial separation, introduces longitudinal focus offset, and enables detection of multiple diffraction orders. This multi-functionality improves beam analysis precision while avoiding the need for multiple separate optical components, thereby managing device complexity
Solution Approach 2:
The diffractive structure creates multiple copies of the incident beam with different propagation characteristics (lateral positions and longitudinal focuses). These copied sub-beams provide redundant information about the droplet position and beam properties, enhancing measurement accuracy without requiring additional independent measurement systems
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
Enables precise analysis of light beam properties and geometric parameters, enhancing the accuracy of droplet positioning and laser beam adjustment, even under conditions of low light intensity, with increased design complexity accepting non-trivial focus behavior and diffraction effects.
Implementation Method 1
the beam-splitting optical arrangement has a diffractive structure; and wherein this diffractive structure is configured in such a way that at least two of the sub-beams are spatially separated from one another on the sensor arrangement and have a focus offset in the longitudinal direction
Data Source
AI summary
A beam propagation camera has at least one beam-splitting optical arrangement (240) configured to split a beam, which is incident on the beam-splitting optical arrangement along an optical axis (OA) of the beam propagation camera, into a multiplicity of sub-beams, and a sensor arrangement (250) configured to detect the sub-beams. The beam-splitting optical arrangement has a diffractive structure (241) configured such that at least two of the sub-beams are spatially separated from one another on the sensor arrangement and have respective foci longitudinally offset from one another along the optical axis.