Solid-state laser rod end surface protection against film breakage
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Solution Overview
Problem
In solid-state laser devices, the antireflection film on the end surface of the laser rod tends to break due to high energy density when using a small-diameter laser rod, leading to instability and potential damage from laser light reflection.
Innovation Solution
A solid-state laser device with a chamfered portion on the laser rod's end surface and an end-surface protection member that limits the laser light path within the outer periphery, using a ceramic or fluororesin protection member to prevent film breakage and ensure stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a small-diameter laser rod is used to reduce pulse width and device size, then productivity and compactness are improved, but the antireflection film on the end surface breaks due to high energy density
Solution Approach 1:
An end-surface protection member is introduced as an intermediary component between the laser rod end surface and the external environment. This protection member has an opening smaller than the laser rod diameter, which limits the laser light path and prevents high-energy density concentration at the antireflection film, thereby preventing film breakage while allowing the small-diameter rod to maintain its high productivity benefits
2Duration of action of moving object
If the laser rod diameter is reduced to achieve shorter pulse width, then energy density increases and pulse width decreases, but the antireflection film breaks due to excessive energy concentration
Solution Approach 1:
The end-surface protection member creates a localized modification in the laser light path by providing an opening smaller than the laser rod diameter. This local quality change restricts the laser beam to a specific region, preventing energy concentration at the vulnerable antireflection film area while maintaining the overall small-diameter configuration that enables short pulse width operation
3Strength
If a chamfered portion is added to the laser rod end surface to prevent chipping, then manufacturing robustness is improved, but the chamfered rough surface prevents satisfactory optical film adhesion
Solution Approach 1:
The end surface structure is segmented into two functional zones: the chamfered portion that provides mechanical strength and prevents chipping, and the central flat portion that maintains smooth surface for optimal optical film adhesion. The end-surface protection member further segments the laser light path to exclude the chamfered region from the active beam path, allowing both rough and smooth surfaces to coexist without compromising optical performance
Data Source
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AI summary
Provided is a solid-state laser device that suppresses occurrence of coating breakage on a laser rod end surface. A solid-state laser device (1) includes a resonator composed of a pair of mirrors (11, 12); a laser rod (13) disposed in the resonator, the laser rod (13) including an antireflection film (14) on an end surface (13b) thereof and having a chamfered portion (13d) at a peripheral edge of the end surface (13b); and an end-surface protection member (60) that is disposed at a position facing the end surface (13b) of the laser rod, that has an opening defining portion (62) that forms an opening (61) whose diameter is smaller than a diameter of an outer periphery of the end surface (13b), and that limits a laser light path region in the end surface (13b) of the laser rod to a region inside of the outer periphery of the end surface (13b).