Achromatic Quartz and MgF2 Retarders

These retarders are a combination of quartz and MgF₂ crystal plates which are cut parallel to the optical axis and polished to a parallelism of λ/10. They are supplied mounted in a cylindrical holder engraved with the „fast axis", the wavelength range and the path difference (λ/2 or λ/4). The combined units have a prismatic deviation of up to about 1'.
As standard these plates are produced for the following wavelength ranges. The curves shown are calculated and can be met with an accuracy of about one percent in production. For simplicity, only the curves for the λ/2 plates are shown. The curves for the λ/4 plates are exactly half the shown values.

Range 1: 180 - 300 nm

Four-part combination each with a double plate of synthetic quartz and MgF₂ mounted in a special holder with an air gap between the individual plates. Single layer antireflection coating on the quartz plates. Accuracy of path difference ± 10%.

Standard version

Range 2: 300 - 470 nm

Three- to four-part combination. Available either cemented between AR coated plane parallel plates of synthetic fused silica or cementless with air gaps and broadband AR coating of all surfaces . Accuracy of path difference ± 5%.

Standard version

Air spaced version

Range 3: 460 - 680 nm

Two-part combination. Available either cemented between AR coated plane parallel plates of crown glass BK7 or cementless with air gap and broadband AR coating of all surfaces . Accuracy of path difference ± 3%.

Standard version

Air spaced version

Range 4: 500 - 900 nm

Same constructions as in range 3 but with accuracy of path difference ± 6%.

Standard version

Air spaced version

Range 5: 600 - 1200 nm

Same constructions as in range 3 but with accuracy of path difference ± 5%.

Standard version

Air spaced version

Range 6: 700 - 2500 nm

Two-part combination without cover plates, available either cemented with single layer AR coating on the quartz plate or cementless with air gap and broadband AR coating of all surfaces . Accuracy of path difference ± 4%.

Standard version

Air spaced version

Note

The length of the holders is 10-15 mm.

Available on special order

• Retarders can also be supplied for other ranges (we usually have a selection in stock) → on request