Low layer count reflective polarizer with optimized gain

A reflective polarizer having a block axis and a pass axis corresponding respectively to an x-axis and a y-axis, the reflective polarizer comprising:

• first and second opposed major surfaces exposed to air and therefore exhibiting Brewster angle reflection minima, the major surfaces being disposed perpendicular to a z-axis which is itself perpendicular to the x- and y-axes, the z-axis and the y-axis forming a y-z plane;
• and
• a stack of microlayers disposed between the major surfaces and arranged into pairs of adjacent microlayers that exhibit refractive index differences along the x-, y-, and z-axes of Δnx, Δny, and Δnz respectively, where Δnx>Δny>0>Δnz, the stack having a total number N of such microlayers;
• wherein the number N and the index difference Δnx in combination are large enough to provide the polarizer with a high reflectivity for normally incident light polarized along the x-axis, such high reflectivity referred to as Rblocknormal, Rblocknormal being at least 80%;
• wherein the number N and the index difference Δny in combination are small enough to provide the polarizer with a low reflectivity for normally incident light polarized along the y-axis, such low reflectivity referred to as Rpassnormal, Rpassnormal being 25% or less;
• and
• wherein Δny is responsible for an incremental portion Rpassinc of Rpassnormal, and a corresponding portion of Δnx equal to Δny is responsible for an incremental portion Rblockinc of Rblocknormal, and the number N is small enough so that Rblockinc is at least half of Rpassinc, and wherein Rpassnormal, Rpassinc, Rblocknormal, and Rblockinc are all averages over a same wavelength range.