Expedited Fabrication of Conformal Window for ABL

Period of Performance: 02/14/2005 - 11/14/2005


Phase 1 SBIR

Recipient Firm

Schafer Corp.
321 Billerica Road
Chelmsford, MA 01824
Principal Investigator


MDA and Air Force are interested in advanced infrared optical windows for high-energy laser systems. The conformal window of ABL uses low OH- content reformed Infrasil 302 (fused quartz). This 2.2 cm thick, 1.71 m diameter, highly curved (ROC=1.31 m) widow is transparent across the visible and IR Bands. It is the leading edge of the ABL aircraft and must survive tactical airborne operations. Fracture of the window can represent a single point failure for the entire ABL system. Proper design of the window is critical! In Phase I Schafer, will use our GlassDESIGNT code to generate laser glass formulations that are low melting, low viscosity and castable (e.g. phosphate, aluminosilicate and borosilicate glasses). Our team partner Schott Glass will produce coupons and preliminary properties data for the top 2 formulations and explore thermal and chemical tempering as a post-processing strengthening technique. Compressive residual stress at the surface of the window is highly desirable. In Phase II we will characterize the candidate window materials, downselect the most promising glass formulation, and build a sub-scale prototype conformal window for the ABL. Key investigations will explore methods for expedited manufacturing, including polishing and figuring processes; and measuring internal stresses.