S & R Optic GmbH
Enabling Crystal Optics Solutions

Selection guide for waveplates / retarders

Retardation plates come in three basic types:

  1. 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.

  2. 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.

  3. 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.



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

  1. is directionally stable,

  2. is well collimated,

  3. has narrow spectral bandwidth,

  4. travels in a thermally stable environment,

  5. 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
@ 500 nm

negligible

slight

negligible

negligible

few percent

few percent

< 1%

Damage threshold, pulsed
@ 1064 nm, 10-20 ns

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
@ VIS - NIR

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