Laser Processing Head Cooling for Thermal Lens Stability
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Solution Overview
Problem
The thermal lens effect and heat conduction in laser processing heads cause fluctuations in focal position and optical axis shifts, leading to processing defects due to excessive temperature increases in optical elements and their holders.
Innovation Solution
A laser processing head with internal refrigerant flow paths that cool the holder and conversion element, using refrigerant to suppress temperature increases and minimize thermal lens effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an optical element is inserted into the laser beam luminous flux to convert the beam profile, then the beam profile is converted as desired, but the optical element absorbs thermal energy from the laser beam causing temperature increase and thermal lens effect
Solution Approach 1:
A refrigerant is introduced as an intermediary cooling medium that flows through a flow path formed in the holder. The refrigerant absorbs thermal energy from the optical element through the holder structure, preventing excessive temperature rise while maintaining the optical element's beam profile conversion function
Solution Approach 2:
A liquid refrigerant is circulated through a hydraulic flow path integrated into the holder structure. This hydraulic cooling system efficiently removes heat from the optical element by circulating the refrigerant through the holder, maintaining thermal stability during laser beam processing
2Temperature
If the optical element is cooled using conventional external cooling methods, then temperature control is achieved, but the holder and optical element experience thermal expansion and optical axis shifts
Solution Approach 1:
The flow path is nested directly within the holder structure, with the refrigerant flow channel formed as an integral part of the holder. This nested configuration enables direct thermal coupling between the refrigerant and the optical element through the holder, providing efficient cooling while minimizing thermal gradients that cause expansion and misalignment
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 cooling system effectively maintains stable processing accuracy and stability by reducing temperature fluctuations and optical axis deviations, preventing processing defects.
Implementation Method 1
the heat is transferred from the heated optical element to a holding member of the drive unit that holds the optical element
Implementation Method 2
a first flow path that is formed inside the shaft connected to the holder that holds the conversion element, and causes the refrigerant to flow toward the holder, and a second flow path that returns the refrigerant from the holder side
Implementation Method 3
thermal energy converted by absorbing part of the laser beam increases the temperature of the optical element
Implementation Method 4
the holding member increases in temperature and thermally expands
Data Source
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AI summary
A conversion element (71) converts a beam profile of a laser beam (Ls) that is supplied from outside and emitted from a nozzle (215). A holder (61) holds the conversion element (71). The holder (61) is connected to a tip end of a shaft (62). An actuator (64) moves the shaft (62) such that the conversion element (71) enters a luminous flux Ls1 of the laser beam Ls and retracts therefrom. A first flow path (FR1) that enables a fluid that is a refrigerant (FL1) to flow from a base side of the shaft (62) toward a holder (61) side of the shaft (62) is formed inside the shaft (62), and a second flow path (FR2) that enables the fluid flowing through the first flow path (FR1) to return from the holder (61) side of the shaft (62) to the base side is formed inside the shaft (62).