Hello Roger,

You asked a similar KudoZ question several months ago:
http://www.proz.com/kudoz/1767318

The Kanji 被 means "the subject of an action" or "to be bestowed upon" and is used in terms such as:

被説明変数 (the explained variable in statistics)
被告 (the defendant of a lawsuit)
被害者 (the victim or injured party)

So 被記録材 is the 'material / part / piece being recorded on' ...there is probably a better pro-noun that would work with your translation. Like 'the record', 'the disc', 'the tape' or whatever is getting recorded onto.

So the whole sentence is saying, "The distance between the orifice surface of the recording head and *thing being recorded on* is approximately 0.5 to 1.0 mm."

Insert the proper term between * *.

ほな。

Plural form is used: Many types of physical media.