Assertion: telescope's purpose | /r/HasProperty | focal length check
Facets:
Source sentences:
text: In fact the refractive null corrector hinted that something was wrong with mirror's figure, but this was rationalized away in favor of the reflective null corrector data because the reflective one was more precise and provided complete (albeit false) figure information, and the purpose of the focal length check was a focal length check and not a figure check.