Selection guide for waveplates / retarders
Retardation plates come in three basic types:
Multiple order plates: They create a large phase difference, several times the wavelength plus a fraction of the wavelength, but only the fraction is effective because multiples of 2π cancel out.
Quasi zero order plates: They consist of a pair of almost identical multiple order plates with crystal axes oriented orthogonally, such that only the difference in phase retardation is effective.
True zero order plates: They are extremely thin, such that they create a phase difference which is truly only a fraction of a wavelength.
The best type from a purely optical point of view is always the true zero order plate: It is fairly insensitive to wavelength compared to the multiple order plate, but in contrast to the quasi zero order plate it is also highly insensitive to angle of incidence.
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For an in-depth discussion of the differences between the various types of waveplates, you might study one of the application notes (available in English and German) which you find in our download area.
Whenever the wavelength is likely to change or whenever the spectral bandwidth is not extremely limited, a multiple order plate is not a good choice.
Whenever the beam direction is likely to change or whenever the beam is divergent or convergent, neither a multiple order plate nor a quasi zero order plate is a good choice.
A true zero order plate is a good technical choice under all conditions that make the other types unsuitable.
| Dependence of Retardation on: | ||
| Wavelength and Spectral Bandwidth | Beam Direction and Beam Divergence | Temperature |
Multiple Order | High | High | High |
Quasi Zero Order | Low | Very High | Low |
True Zero Order | Low | Low | Low |
However, if your light beam
is directionally stable,
is well collimated,
has narrow spectral bandwidth,
travels in a thermally stable environment,
has low intensity, both spatially and temporally,
then the type does not matter too much, and you might make your selection mainly based on price and other optical properties which are important for all kinds of optical components.
The following table supports you in finalizing your selection:
Material | Quartz | Quartz | Quartz | Quartz | Mica | Mica | Polymer |
Type | Multiple order | Quasi zero order | Quasi zero order | Quasi zero order | True zero order | True zero order | True zero order |
Mounting | Bare | Cemented | Optically contacted | Air spaced | Cemented | Bare | Cemented |
Useable wavelength range (nm) | 193 – 2000 | 400 – 2000 | 193 – 2000 | 193 – 2000 | 400 – 1550 | 350 – 1550 | 400 - 1550 |
Practical max. diameter | 50 mm | 50 mm | 50 mm | 50 mm | 200 mm | 200 mm | 200 mm |
Typical absorption | negligible | slight | negligible | negligible | few percent | few percent | < 1% |
Damage threshold, pulsed | 10 J/cm² | 0.5 J/cm² | 10 J/cm² | 10 J/cm² | 0.5 J/cm² | 10 J/cm² | 4 J/cm² |
Damage threshold, cw | 10 MW/cm² | 1.5 kW/cm² | 1 MW/cm² | 1 MW/cm² | 0.5 kW/cm² | 0.5 kW/cm² | 0.5 kW/cm² |
Homogeneity of retardation over aperture (typ. 25 mm) | λ/500 | λ/300 | λ/500 | λ/500 | λ/300 | λ/300 | λ/100 |
Precision of retardation | λ/300 | λ/200 | λ/300 | λ/300 | λ/200 | λ/200 | λ/100 |
Temperature dependence of retardation per °C | 0.3 % | negligible | negligible | negligible | negligible | negligible | 0.04 % |
Price @ low quantity | high | high | high | very high | low | medium | very high |
Price @ medium quantity | low | medium | medium | high | very low | low | medium |
Price @ high quantity | low | medium | medium | medium | very low | very low | low |