A couple weeks ago we reported thatApogee had released a roughly estimated correction factorfor measuring light underwater. Due to the the interaction of water and light and the immersion effect of the opaque sensor cover, it turns out that their new meter works perfectly for measuring PAR in air, but needs some slight adjustment when submerged in water.
校正最终使旧的Apogee MQ-200 PAR仪增加了7％，而新的MQ-500 PAR表则增加了32％的颠簸。但是，如果您有兴趣在水族馆中更准确地读取光合活性辐射，那么Apogee已正式发布了水下PAR校正计算器。
As it turns out, characterizing the behavior of light through air, reflection from the surface of water and then through water is a little bit more involved than a simple percentage bump. The apogee underwater PAR Measurement calculator accounts for most of these variables and asks users to describe the distance of the light source from the sensor, and how much of that distance is through air and how much is through water.
The calculator itself is a simple spreadsheet which can be downloaded and saved for future use to correct the values displayed by Apogee’s PAR Meters. For a rough estimate of your PAR lighting intensity you can still use the simple percentage multiplier and get pretty close, but it’s nice to know that more accurate values are available to those who are willing to crunch just a few numbers. [Apogee]
