Becke-line comparison of refractive index
In a suitable transmitted-light grain–medium boundary test, increasing the objective-to-specimen separation moves the Becke bright line into the material of higher refractive index.
Key knowledge
In a suitable transmitted-light grain–medium boundary test, increasing the objective-to-specimen separation moves the Becke bright line into the material of higher refractive index. Relief decreases near index matching. Comparison with calibrated immersion media can constrain a grain's refractive index at a specified wavelength and temperature.
Conditions and scope
- Use a appropriate grain boundary, illumination/aperture and a documented focus direction; changing stage height and moving the objective can reverse a verbal 'focus up' instruction.
- Anisotropic grain indices depend on orientation and polarization. Dispersion, medium temperature and calibration limit precision; a Becke-line observation alone is not a chemical identification.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read the actual grain/oil comparison and objective-distance direction; recast it to avoid instrument-dependent up/down wording. Retained wavelength/medium constraints, not a full calibrated immersion-index uncertainty budget.
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Entry details
Permanent link to this entry ↗- Record identity
- uni-earth-becke-refractive-index
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- core.1
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- University core expansion