picoammeter

The picoammeter reads the current at the last dynode, which is equal to the anode current minus the current flowing to the previous dynode.

皮安计在最后增管电极处读取电流，此电流等于阳极电流减去流过前增管电极的电流。

The big disadvantage is the loss of accuracy and resolution, but some digital picoammeters combine accuracy and dynamic range by combining autoranging and digital log conversion.

这种方法，较大的缺是损失了度分辨率。然而，也有些数字式皮安表，采用自动量程数字对数变换的方法，这可将宽动态范围结合了起来。