Ultrafast laser strain generation for nanometer-precision alignment of optical components

Optical systems such as X-ray telescopes or micro-optical systems can require alignment of optical components with nanometer-level tolerances, and often with stringent volume and mass requirements. We propose fabricating, bonding, and subsequently adjusting length of glass spacers using ultrafast lasers. Ultrafast laser processing has been industrialized over the last decade for micron-accuracy glass cutting with complex shapes, and for glass-to-glass and glass-to-metal welding. In this paper, we will show experimental results demonstrating the ability to generate stable strain in Corning® Eagle XG® glass samples, which causes permanent nanometer-scale length changes. We demonstrate a total strain of ∼10-3, or microns of displacement per millimeter length of laser-modified glass. We also measure stability in laser-modified samples and find that the length changes are nanometer-stable. We also show how this process may be applied for alignment of X-ray mirrors by combining industrialized ultrafast laser processes for glass cutting and glass-to-glass welding with strain generation and control. This powerful and flexible process may enable compact, lightweight set-and-forget alignment of optical systems with nanometer tolerances.