Quarter Wave & Half Wave Retarder

How it Works: Quarter Wave & Half Wave Plate

API’s quarter wave plate and half wave plate are single-layer polycarbonate films offering great performance and clarity. Our quarter wave retarders are available in 500nm (125nm OPD), 560nm (140nm OPD), and 660nm (165nm OPD). Our half wave retarder is available as 560nm (280nm OPD).

Our wave plates feature uniform birefringence, low haze, good environmental stability, and excellent wide-angle view performance.

API can laminate the above-listed quarter wave and half wave films to acrylic and glass for added durability and improved optical performance.

  • 1/4 Wave & 1/2 Wave Films
  • Quarter Wave Plates Available in Multiple Wavelengths
  • Achromatic Quarter Wave at 140nm OPD also available
  • High Clarity and High-Temperature Performance
  • Polycarbonate Based Films
  • Can be Laminated Between Glass or Acrylic for Increased Durability
  • In-House Laser & Waterjet Cutting for Acrylic & Glass Laminates

How does a quarter wave retarder work?

Wave retarders are birefringent materials that alter (retard) the polarization state or phase of light traveling through them.  A wave retarder has a fast (extraordinary) and slow (ordinary) axis.

As polarized light passes through a wave retarder, the light passing through the fast axis travels more quickly through the wave retarder than through the slow axis.  In the case of a quarter wave retarder, the wave plate retards the velocity of one of the polarization components (x or y) one-quarter of a wave out of phase from the other polarization component.

Polarized light passing through a quarter wave retarder thus becomes circularly polarized (see Figure 1).  The action of the quarter wave is sometimes referred to as twisting or rotating the polarized light.  Note that depending on which polarization component is retarded, one will have either a left-handed or right-handed circular polarizer.

Wave retarders: how it works

On the other hand, a half wave plate (two quarter wave plates combined) will not create circularly polarized light but, instead, rotate the input polarized light 90º.

Retardation films can be referenced in two ways:  the Optical Path Difference (OPD) or the Center Wavelength.  For example, if one references a wave retarder by the OPD, you would say “1/4 wave at 140nm”.  That same wave retarder can also be referenced as “1/4 wave centered at 560nm.”

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