Laser Optical Element Thermal Mapping for Precise Focus Control
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Solution Overview
Problem
Conventional laser processing systems face challenges in accurately compensating for thermally induced focus offsets in optical elements due to temperature gradients, leading to reduced processing quality in applications like laser cutting and welding.
Innovation Solution
A device with a thermopile matrix for measuring two-dimensional temperature distributions on optical elements, combined with a heating system and thermal insulation, actively adjusts the focal position by heating the optical element to achieve a homogeneous temperature distribution and precise focus control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If lens cooling is used to remove heat from the center of the lens, then heat removal is improved, but temperature gradient and focus shift worsen
Solution Approach 1:
Instead of cooling the lens center to remove heat (conventional approach), the patent applies heating elements to the lens periphery. This inverted approach—heating the edges rather than cooling the center—creates a temperature distribution that compensates for the thermal lensing effect, thereby maintaining focus position while managing heat
Solution Approach 2:
The patent applies different thermal treatments to different regions of the lens: heating elements are placed at the periphery while the center remains relatively cooler. This localized quality approach creates a specific temperature gradient pattern that compensates for focus shift without causing additional thermal distortion
2Manufacturing precision
If passive compensation with different lens materials is used, then focus shift compensation is improved, but adaptability to all applications worsens
Solution Approach 1:
The patent employs actively controllable heating elements that can be dynamically adjusted in power and timing. This dynamic control allows the system to adapt to different laser powers, pulse durations, and material processing requirements, making it versatile across various applications unlike static passive compensation methods
Solution Approach 2:
The heating elements allow dynamic change of thermal parameters (temperature, heating rate) based on process requirements. By controlling the heating parameters electronically, the system can adapt to different laser processing conditions, material types, and power levels, providing universal applicability
3Device complexity
If one-dimensional temperature measurement is used, then measurement simplicity is improved, but focus compensation precision worsens
Solution Approach 1:
The patent transitions from one-dimensional (single point) temperature measurement to two-dimensional temperature mapping by placing multiple thermocouples at different radial positions on the lens periphery. This dimensional expansion provides comprehensive temperature distribution data necessary for precise focus compensation
4Manufacturing precision
If conventional focus compensation methods are used, then processing quality consistency worsens under varying thermal conditions, but switching to active thermal control improves compensation precision
Solution Approach 1:
The patent implements a feedback control system where thermocouples continuously monitor lens temperature and the controller adjusts heating element power accordingly. This closed-loop feedback ensures precise focus compensation that adapts to varying thermal conditions, maintaining processing quality despite changes in laser power or environmental conditions
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 enables high-precision compensation of focus shifts, maintaining consistent processing quality across various laser applications by accurately managing temperature gradients and refractive index variations.
Implementation Method 1
a temperature detector arrangement with a thermopile matrix that is set up to measure a two-dimensional temperature distribution of the optical element
Implementation Method 2
at least one heating device which is arranged on the optical element in order to supply thermal energy to the optical element
Implementation Method 3
The optical element can be set up to focus and/or collimate a laser beam
Implementation Method 4
local heating can occur due to absorption of laser energy. This absorption leads to a temperature gradient that locally changes the refractive index n(T) of the lens. The different refractive indices of the lens cause the laser focus to shift
Data Source
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Figure 3A~3B
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AI summary
The invention relates to a device (100, 600) for a laser working system, comprising at least one optical element (110, 610), which is arranged in a beam path of the device, and one temperature detector assembly (105, 620) having a matrix of detector elements, which temperature detector assembly is designed to measure a two-dimensional temperature distribution of the optical element (110, 610).