Head-up display system with half waveplate optimized for better performance

An interlayer, comprising:

• (a) a first polymer layer;
• and
• (b) a half waveplate (“HWP”) film comprising a polymeric material,
• wherein the HWP film has a plane and an optical axis, wherein the optical axis has an angle phi (ϕ) relative to the axis formed from the p-polarization direction of a display light projected onto the plane of the HWP film,
• wherein Φ is from an angle of 30° to less than 45°, an angle of greater than 45° to 55°, an angle of greater than 135° to 150°, or an angle of 125° to less than 135°, and
• wherein the HWP film exhibits an in-plane retardation measured at 550 nm (“Re[550 nm]”) of from -200 nm to -350 nm or from 200 nm to 350 nm, and an out-of-plane retardation measured at 550 nm (“Rth[550 nm]”) of from -350 nm to 350 nm.