Abstract : The improvement of single-mode precision fiber is critical to the efficient use of these fibers in connectors and to allow for low loss splices. Similarly, the alignment of fibers to integrated optic devices demands high precision. Likewise, the precision of large core multimode fibers affects coupler and connector losses as well as overall optical and physical performance. In accordance with the statement of work (SOW), EOPD has evaluated the parameters that affect the fabrication of high precision 100 micrometer core fiber and single-mode precision fiber. ITT EOPD has completed the full dimensional evaluation of precision shrunk, ground, and polished natural fused quartz tubing. Additionally, ITT has verified the od uniformity of precision shrunk, ground, and polished Vycor brand silica glass tubing. Fibers made from preforms utilizing the above substrates met all requirements of this contract. The large core deliverable had a fiber od of 140 micrometers with a fiber core diameter of 100.1 micrometers, well within the limits of the contract. Other measurements showed the core eccentricity to be less than 0.08%; optical loss at 0.85 micrometers was 7.94 dB/km while the NA was 0.29. Measurements of the low NA deliverable revealed an average NA of 0.11, an od of 80.5 micrometers, and a core eccentricity of 0.20%. For the high NA fiber, the NA value ran 0.20; the od was the same as the low NA, 80.5 micrometers, while the core eccentricity ran less than 0.20%.