optic sign
determined by the relationship of the refractive indices of a material. For uniaxial crystals, if ε > ω, the crystal is positive (+); if ω > ε, the crystal is negative (-). For biaxial crystals, if γ-β > β-α, the crystal is positive (+); if γ-β < β-α, the crystal is negative (-).
Committee
Interdisciplinary
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org