Brewster Window Attenuator for Laser Return Light Isolation
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Solution Overview
Problem
Laser processing apparatuses face damage and oscillation destabilization due to reflected laser light returning to the oscillator, necessitating effective attenuation and suppression of return light.
Innovation Solution
An attenuator device comprising a pair of first windows and a pair of second windows, each forming a Brewster's angle with the optical axis, along with a λ/4 phase element, which together provide a total of eight Brewster surfaces for attenuation and function as an isolator to suppress return light by creating a phase difference and rotating the first window pair to adjust the attenuation rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a pair of windows arranged in a V shape forming a Brewster's angle is used to attenuate laser light, then the attenuation rate can be changed by rotating the windows, but the device complexity increases and the attenuation range is limited
Solution Approach 1:
The device divides the attenuation function into two separate window pairs (first window pair and second window pair), each capable of independent rotation. This segmentation allows each pair to contribute to the overall attenuation independently, enabling a broader attenuation range while maintaining adjustable control through rotation of either pair.
Solution Approach 2:
Each window pair serves dual functions: (1) providing variable attenuation through rotation, and (2) serving as part of an isolator system when combined with the λ/4 phase element. The second window pair specifically is configured to work with the phase element to suppress return light, making the structure multi-functional rather than requiring separate components for each function.
2Reliability
If laser light reflected by a workpiece returns to the laser oscillator, then the oscillator may be damaged or oscillation output may be destabilized, but adding return light suppression components increases device complexity
Solution Approach 1:
The isolator function is merged with the existing window pairs and λ/4 phase element. The second window pair is specifically oriented at 45° to the optical axis of the phase element, and together they form an isolator that suppresses return light. This merging eliminates the need for separate isolator components, achieving oscillator protection without significantly increasing device complexity.
3Reliability
If the second window pair is disposed at 45° to the optical axis of the λ/4 phase element to form an isolator, then return light is suppressed, but the device complexity increases
Solution Approach 1:
The second window pair is configured to simultaneously provide attenuation (through rotation similar to the first pair) and isolator function (when oriented at 45° to the phase element). This multi-functionality means the same component structure serves dual purposes, reducing the need for additional dedicated isolator components and minimizing the increase in device complexity while achieving reliable return light suppression.
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 attenuator device achieves a large attenuation range and effectively suppresses return light, ensuring the laser processing apparatus operates safely and efficiently by adjusting the attenuation rate based on target intensity.
Implementation Method 1
each of the pair of first windows including a pair of first surfaces extending to form a Brewster's angle with the optical axis
Implementation Method 2
approximately 100% of a P-polarized component is transmitted, while only about 50% of an S-polarized component is transmitted
Implementation Method 3
gives a phase difference of λ/4 between a polarized component parallel to an optical axis and a polarized component orthogonal to the optical axis
Implementation Method 4
the second window pair and the λ/4 phase element function as an isolator and the return light can be removed
Data Source
AI summary
An attenuator device includes: a first window pair that includes a pair of first windows having a pair of first surfaces extending to form a Brewster's angle with an optical axis; a rotation holding portion which holds the first window pair to be rotatable around the optical axis; a second window pair that includes a pair of second windows having a pair of second surfaces extending to form a Brewster's angle with the optical axis; and a λ/4 phase element which gives a phase difference of λ/4 between a polarized component parallel to an optical axis and a polarized component orthogonal to the optical axis when a wavelength of laser light is λ. The second window pair is disposed so that a vibration direction of a P-polarized component transmitted through the second window pair is inclined with respect to the optical axis of the λ/4 phase element by 45° when viewed from a direction parallel to the optical axis.