Until about 1950, glasses were melted in clay or ceramic crucibles and these materials were often attacked by the melt. It proved almost impossible to remove all minute air bubbles, and for many years such bubbles in lens elements were taken as proof of a quality lens made using highly refractive dense glass. Nowadays, all melts are made in platinum crucibles to avoid deterioration as well as trace contaminations, but one of the quirks of old lenses is these small bubbles. Air bubbles in lens elements were very common in older lenses.
By the late 70's and early eighties, when lenses was made, they were becoming less common as manufacturing techniques improved. If they are, in fact, just air bubbles, you should be fine. Embrace the imperfections.See also "Why does the aperture not cause vignetting when it gets smaller?" in the Aperture section HERE
For more information read sections on Optical Design
, Chromatic Errors
, Lens Flare
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