luminous efficacy of radiant flux
视见函数，光见度

• bearing tracking
• beat
• beat effect
• beat frequency
• beat frequency detector
• beat frequency interferometry
• beating
• beat setting
• beat spectrum
• beat wavelength
• beauty defect
• beauty defects
• beavertail
• bechstein photometer
• Beck apertometer
• becke apertometer
• Becke line
• Beckman spectrophotometer
• Becquerel
• Becquerel effect
• Beer-Lambert law
• Beer's Law
• beeswax
• bega
• bel