Tangent screen
(campimeter)切线幕(视野计)

• underswing
• underwater camera
• underwater laser radar
• underwater TV camera
• underwater visibility
• underwater vision
• undeveloped
• undeviated light
• undiffracted wave
• undissolved substance
• undistorted
• undistorted image
• undistorted wave
• undisturbed
• undoped
• undoped diode
• undoped single crystal
• undosed
• undulating light
• undulation
• undulatory
• unearthed
• uneven front
• uneven grain
• unevenness