Achromatic waveplates
Achromatic waveplate (AWP) is a pair of crystal
quartz and magnesium fluoride plates. Because of difference in
dispersion in these uniaxial positive crystals it is possible to
calculate thickness of each plate so that birefringent phase shift
in assembly changes very slowly over certain wavelength range.
This is a way to obtain achromatic zero order waveplates. Such
AWPs are necessary for various devices and may replace a number
of ordinary quartz waveplates operating at a single wavelength
only.
Elan makes a series of achromatic waveplates with phase shifts
shown in graphs below.
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Achromatic zero order l/4 wave plate
for 0,6 – 1,1 mkm |
Achromatic zero order l/2 wave plate for 0,6 – 1,1 mkm
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Achromatic zero order l/4 wave plate for 0,4 – 0, mkm
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Achromatic zero order l/2 wave plate for 0,4 – 0,6 mkm
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Specification
| Design |
High Power Air Spaced |
| Material |
Quartz + MgF2 |
| Transmitted wave front distortion |
λ/10 @ 633 nm |
| Tolerance for diameter |
+0,0/-0,25 nm |
| Parallelism |
30 arc sec |
| Surface quality |
20/10 |
| AR coating |
R<0,5% over wavelength range |
| Retardation tolerance |
not less than λ/100 average |
Standard dimensions and wavelength ranges
| Dia, mm |
Wavelength range,
nm. |
| 12.7 -0.2 |
400
– 600 |
600
– 1100 |
| 25.4-0.2 |
Non standard dimensions are available upon request.
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