| 摘要 |
THE INVENTION RELATES TO LEAD-FREE OPTICAL BARIUM FLINT GLASSES HAVING REFRACTIVE INDICES ND OF BETWEEN 1.55 AND 1.66 AND ABBE NUMBERS VD OF BETWEEN 39 AND 52, WHICH HAVE THE FOLLOWING COMPOSITION (IN BY WEIGHT BASED ON OXIDE) :SIO2 40 - 60; B2O3 6. 5 -12 ; BAO 10-35; CAO 0-1; ZNO 0-2; TIO2 5-12; AL2O3 0.5-3.5; NA2O 3-7.5; K2O 3-8; WITH NA2O+K2O <15;THE GLASSES HAVE A POSITIVE ANOMALOUS TO NORMAL PARTIAL DISPERSION IN THE BLUE RANGE OF THE SPECTRUM.
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