visual standard irradiance
可见标准辐照度

• porous glass
• porous material
• porphyrin
• Porro prism
• Porro prism erecting system
• Porrotelescope
• port
• portable camera
• portable laser
• portable transit
• port-hole
• Portland cement
• portrait lens
• portraying atmospheric turbulence
• posie
• posinjeciton
• position
• positioner
• position-filar micrometer
• position finder
• position finding
• position hologram
• positioning
• positioning dowel
• positioning error