optically-thicker medium
光密媒质

• robotization
• Rochon prism
• rochon prismsRochon
• rock crystal
• rocker
• rocker arm
• rocket
• rocket-borne
• rocketry
• rocking grating
• rocking grating spectrometer
• rocksalt
• Rockwell hardness tester
• rock wool
• rod
• rod guide
• rod of the retina
• rod radiator
• rod-shaped flash lamp
• rod vision
• roentgen
• roentgengraphy
• roentgenization
• roentgenkymography
• roentgenogram