Refractive-index changes caused by proton radiation in silicate optical glasses

Area of Science:

• Materials Science
• Optical Engineering
• Radiation Physics

Background:

• Optical systems in radiation environments require materials resistant to spectral degradation.
• Radiation-hardened glasses are crucial for maintaining optical performance under irradiation.
• Existing radiation-hard glasses do not prevent refractive index changes.

Purpose of the Study:

• To experimentally investigate the impact of proton radiation on the refractive index of commercial silicate crown glasses.
• To compare the radiation-induced refractive index changes in standard glasses (BK7, LaK9) and their radiation-resistant counterparts.
• To assess the implications of these refractive index changes for optical system performance.

Main Methods:

• Differential interferometric technique was employed for precise measurement of refractive index changes.
• Proton radiation was applied to samples of BK7, LaK9, and their radiation-hardened variants.
• Refractive index shifts were quantified at a specific radiation dose.

Main Results:

• Proton radiation was observed to affect the refractive index of all tested silicate crown glasses.
• The radiation-hardened lanthanum crown glass (LaK9G15) exhibited the most significant refractive index change.
• At a 0.65-Mrad dose, LaK9G15 showed an approximate refractive index change of 3 x 10(-5).

Conclusions:

• Radiation-hardened glasses, while preventing spectral degradation, are susceptible to refractive index perturbations from proton radiation.
• These radiation-induced refractive index changes can lead to optical aberrations.
• Diffraction-limited optical systems utilizing these glasses may experience performance failures due to radiation-induced aberrations.