ring-shaped aperture
环形孔，环形孔径

• cyclooctatetraene
• cyclophon
• cycloplegics
• cyclopropane
• cyclorotaion
• cyclotron
• Cyclotron Frequency
• Cyclotron Radiation
• Cyclotron Resonance
• cyclotron resonance detector
• cyclotron resonant
• cyclotron responsance maser
• cylincrical lens
• cylinder
• cylinder diaphragm
• cylinder functions
• cylindergauge
• cylindrial harmonics
• cylindrical anamorph
• cylindrical bearing
• cylindrical cavity
• cylindrical coordinates
• Cylindrical Lens
• cylindrical lenticulation
• cylindrical mirror