The layered waveplate (1) is formed by a first waveplate (2) and a second waveplate (3).

It is possible to provide a layered waveplate having a wide range with a desired phase difference.

The second waveplate (3) has a phase difference Γ2 and an in-plane azimuth angle 43.5 degrees.

The first waveplate (2) has a phase difference Γ1 = 360 degrees and an in-plane azimuth angle -8 degrees.

The layered waveplate functions as a desired phase difference Γ2 in a wavelength range 600 nm to 800 nm as a whole.

The layered waveplate (1) is formed by a first waveplate (2) and a second waveplate (3).

Preferably, the retarder layer is a quarter wave retarder.

In one embodiment, a first substrate is a nλ waveplate and the second substrate is a (n+ Δ )λ waveplate.

A novel retardation plate is disloced.

The incremental retardation produces a desired amount of retardation of a lightwave passing through the compensated higher order waveplate.

The radiation source includes a phase plate structure including one or more phase plates.

The substrates are oriented so that their principle axes of retardation are orthogonal. nλ, is a base retardation of a waveplate and Δ λ, is an incremental retardation.

The composite retardation plate may further comprise a polarizing plate preferably laminated on the side of the resin retardation plate, thereby providing a composite optical member.

The wave plate is positioned in the optical path of the optoelectronic device.

A compensated higher order waveplate is constructed of substrates.