Patent ID: 11874576
Assignee: REALD SPARK, LLC
Field: Optics (Instruments)
Classification: CPC G | IPC F  G

Claim 5:
6. A display device according to claim 5, wherein
the two passive retarders introduce no net, relative phase shift to orthogonal polarisation components of light passed by the display polariser along the first axis, and
the at least one passive retarder comprises a further two passive retarders which have optical axes in the plane of the further two passive retarders that are crossed, the further two passive retarders being respectively included in the at least one air gap output retarder and the at least one air gap input retarder, the further two passive retarders introducing no net, relative phase shift to orthogonal polarisation components of light passed by the display polariser along the first axis, and the one of the further two passive retarders which is arranged in the at least one air gap input retarder being arranged to convert linearly polarised light passed by the display polariser into circularly polarised light.