Hefner candle
(Hefner kerze)赫夫纳烛光

• flash ranging
• flash screen
• flash socket
• flash spectroscopy
• flash synchronzed shutter
• flashtabe
• flash tube
• flashtube lamp
• flash unit
• flask
• flat
• flat angle
• flat-bed color image scanners
• flat blank
• flat CRTs
• flat-field lens
• flat-field objective
• flat inclined mirror
• flat interferometer
• flat key
• flat lapping block
• flat-layer powder camera
• flat machine
• flat mirrors
• flatncess of field