a-middle-polarizer-can-pass-a-crossed-pair - Electromagnetic Waves and Polarization Step by Step

A middle axis can route light through crossed polarizers in this checked chain. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

A middle polarizer can revive a crossed pair

A middle axis with factor 3/5 from the first and 4/5 from the second gives a nonzero final stage.

I_{\mathrm{in}}=25\ \text{W}/\text{m}^{2}\xrightarrow{\frac{3}{5}} 9\ \text{W}/\text{m}^{2}\xrightarrow{\frac{4}{5}} \tfrac{144}{25}\ \text{W}/\text{m}^{2}