Logo

Achromatic Retarders

Achromatic Retarders

Achromatic retarders can be regarded as zero order double plates where the two plates are manufactured from different materials (quartz and MgF22 ). By exploiting the difference of dispersion of the birefringence one achieves an almost constant phase shift over a broader spectral range.

The retarders are available either cemented between cover plates or in a cementless version with air gap. The cemented version is the more economical one and exhibits slightly lower reflection losses. The version with air gap excels in a high damage threshold and low material dispersion.

The retarders are delivered in a cylindrical mount.

We manufacture achromatic retarders for six standard spectral ranges specified below. The diagrams of the path difference versus wavelength shows the values for the half wave plates. For quarter wave plates the retardation has half the value at any wavelength.

The retarders covering short wavelength ranges require one or both of the crystal plates to be manufactured as double plate leading to a total number of three or four plates, respectively. For the cemented version a significant reflection loss only occurs at the two outer surfaces. For the version with air gap reflection losses have to be considered on both surfaces of each plate, namely 4-8 surfaces.

Achromatic retarders with air gap are particularly suited for ultra-short pulsed lasers. For this reason their group delay dispersion (GDD) is specified for a representative wavelength in the table. The dispersion for the cemented version is significantly larger due to the cover plates .

material quartz and MgF2
wavefront distortion <λ/10
prismatic deviation <2'' (air gap), <1' (gekittet)
marked direction fast axis
tolerance of the path difference ±3 nm

Standard dimensions

Format 10 mm 15 mm 20 mm 25 mm
free aperture [mm] 9,5 14,5 19,5 24,5
mount diameter [mm] 25 25 30 40
mount length [mm] 10 10 10 15
Art. Nr.:, all ranges λ/2 RAC X.2.10 RAC X.2.15 RAC X.2.20 RAC X.2.25
Art. Nr.:, all ranges λ/4 RAC X.4.10 RAC X.4.15 RAC X.4.20 RAC X.4.25
Art. Nr.:, all ranges λ/2 air gap RAC X.2.10 L RAC X.2.15 L RAC X.2.20 L RAC X.2.25 L
Art. Nr.:, all ranges λ/4 air gap RAC X.4.10 L RAC X.4.15 L RAC X.4.20 L RAC X.4.25 L
spectral range 1 180-300 nm
deviation of retardation ± 8,5%
number of plates 4
reflectivity quartz: <2% MgF2: <3%
temperature coefficient* α(typ.) λ/2: 2∙10-3nm/K  λ/4:1∙10-3 nm/K
angular coefficient* ß (typ.) 2,5 nm/deg²
GDD (λ=266 nm) 500 fs²
Bereich 1

* Definition

λ/2 version with air gap

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 1.2.10L 925.- 859.- 784.-
RAC 1.2.15L 1543.- 1416.- 1272.-
RAC 1.2.20L 2536.- 2311.- 2053.-
RAC 1.2.25L 3841.- 3461.- 3028.-

λ/4 version with air gap

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 1.4.10L 925.- 859.- 784.-
RAC 1.4.15L 1543.- 1416.- 1272.-
RAC 1.4.20L 2536.- 2311.- 2053.-
RAC 1.4.25L 3841.- 3461.- 3028.-
spectral range 2 300-470 nm
deviation of retardation ± 5%
number of plates λ/2: 3   λ/4: 4
reflectivity <0,5%
temperature coefficient* α(typ.) λ/2: 0,05 nm/K  λ/4:0,025 nm/K
angular coefficient* ß (typ.) λ/2: 1,5 nm/deg²  λ/4:2,4 nm/deg²
GDD (λ=400 nm) λ/2: 94 fs²  λ/4: 250 fs²
Bereich 2

* Definition

λ/2 version cemented with cover plates

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 2.2.10 786.- 730.- 666.-
RAC 2.2.15 1293.- 1187.- 1066.-
RAC 2.2.20 2099.- 1912.- 1699.-
RAC 2.2.25 3278.- 2954.- 2584.-

λ/4 version cemented with cover plates

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 2.4.10 921.- 855.- 780.-
RAC 2.4.15 1537.- 1411.- 1267.-
RAC 2.4.20 2528.- 2304.- 2047.-
RAC 2.4.25 3921.- 3534.- 3091.-

λ/2 version with air gap

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 2.2.10L 888.- 824.- 752.-
RAC 2.2.15L 1483.- 1361.- 1222.-
RAC 2.2.20L 2430.- 2214.- 1967.-
RAC 2.2.25L 3585.- 3231.- 2827.-

λ/4 version with air gap

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 2.4.10L 1023.- 950.- 866.-
RAC 2.4.15L 1727.- 1586.- 1424.-
RAC 2.4.20L 2860.- 2605.- 2315.-
RAC 2.4.25L 4228.- 3811.- 3334.-
spectral range 3 460-680 nm
deviation of retardation ± 3%
number of plates 2
reflectivity <0,5%
temperature coefficient* α(typ.) λ/2: 0,2 nm/K  λ/4:0,1 nm/K
angular coefficient* ß (typ.) λ/2: 0,8 nm/deg²  λ/4:0,4 nm/deg²
GDD (λ=515 nm) λ/2: 62 fs²  λ/4: 31 fs²
Bereich 3

* Definition

λ/2 version cemented with cover plates

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 3.2.10 592.- 550.- 501.-
RAC 3.2.15 951.- 873.- 784.-
RAC 3.2.20 1541.- 1404.- 1248.-
RAC 3.2.25 2350.- 2118.- 1853.-

λ/4 version cemented with cover plates

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 3.4.10 592.- 550.- 501.-
RAC 3.4.15 951.- 873.- 784.-
RAC 3.4.20 1541.- 1404.- 1248.-
RAC 3.4.25 2350.- 2118.- 1853.-

λ/2 version with air gap

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 3.2.10L 715.- 664.- 606.-
RAC 3.2.15L 1166.- 1071.- 961.-
RAC 3.2.20L 1874.- 1708.- 1517.-
RAC 3.2.25L 2681.- 2416.- 2114.-

λ/4 version with air gap

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 3.4.10L 715.- 664.- 606.-
RAC 3.4.15L 1166.- 1071.- 961.-
RAC 3.4.20L 1874.- 1708.- 1517.-
RAC 3.4.25L 2681.- 2416.- 2114.-
spectral range 4 500-900 nm
deviation of retardation ± 6 %
number of plates 2
reflectivity <0,5%
temperature coefficient* α(typ.) λ/2: 0,3 nm/K  λ/4: 0,15nm/K
angular coefficient* ß (typ.) λ/2: 1,1 nm/deg²  λ/4:0,6 nm/deg²
GDD (λ=800 nm) λ/2: 50 fs²  λ/4: 25 fs²
Bereich 4

* Definition

λ/2 version cemented with cover plates

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 4.2.10 592.- 550.- 501.-
RAC 4.2.15 951.- 873.- 784.-
RAC 4.2.20 1541.- 1404.- 1248.-
RAC 4.2.25 2350.- 2118.- 1853.-

λ/4 version cemented with cover plates

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 4.4.10 592.- 550.- 501.-
RAC 4.4.15 951.- 873.- 784.-
RAC 4.4.20 1541.- 1404.- 1248.-
RAC 4.4.25 2350.- 2118.- 1853.-

λ/2 version with air gap

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 4.2.10L 715.- 664.- 606.-
RAC 4.2.15L 1166.- 1071.- 961.-
RAC 4.2.20L 1874.- 1708.- 1517.-
RAC 4.2.25L 2681.- 2416.- 2114.-

λ/4 version with air gap

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 4.4.10L 715.- 664.- 606.-
RAC 4.4.15L 1166.- 1071.- 961.-
RAC 4.4.20L 1874.- 1708.- 1517.-
RAC 4.4.25L 2681.- 2416.- 2114.-
spectral range 5 600-1200 nm
deviation of retardation ± 5%
number of plates 2
reflectivity <0,8%
temperature coefficient* α(typ.) λ/2: 0,5 nm/K  λ/4: 0,25nm/K
angular coefficient* ß (typ.) λ/2: 1,6 nm/deg²  λ/4:0,8 nm/deg²
GDD (λ=800 nm) λ/2: 75 fs²  λ/4: 37 fs²
Bereich 5

* Definition

λ/2 version cemented with cover plates

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 5.2.10 592.- 550.- 501.-
RAC 5.2.15 951.- 873.- 784.-
RAC 5.2.20 1541.- 1404.- 1248.-
RAC 5.2.25 2350.- 2118.- 1853.-

λ/4 version cemented with cover plates

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 5.4.10 592.- 550.- 501.-
RAC 5.4.15 951.- 873.- 784.-
RAC 5.4.20 1541.- 1404.- 1248.-
RAC 5.4.25 2350.- 2118.- 1853.-

λ/2 version with air gap

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 5.2.10L 715.- 664.- 606.-
RAC 5.2.15L 1166.- 1071.- 961.-
RAC 5.2.20L 1874.- 1708.- 1517.-
RAC 5.2.25L 2681.- 2416.- 2114.-

λ/4 version with air gap

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 5.4.10L 715.- 664.- 606.-
RAC 5.4.15L 1166.- 1071.- 961.-
RAC 5.4.20L 1874.- 1708.- 1517.-
RAC 5.4.25L 2681.- 2416.- 2114.-
spectral range 6 700-2500 nm
deviation of retardation ± 4%
number of plates 2
reflectivity <2%
temperature coefficient* α(typ.) λ/2: 0,6 nm/K  λ/4: 0,3nm/K
angular coefficient* ß (typ.) λ/2: 1,9 nm/deg²  λ/4:0,9 nm/deg²
GDD (λ=1550 nm) λ/2: -59 fs²  λ/4: -29 fs²
Bereich 6

* Definition

λ/2 version cemented with cover plates

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 6.2.10 592.- 550.- 501.-
RAC 6.2.15 951.- 873.- 784.-
RAC 6.2.20 1541.- 1404.- 1248.-
RAC 6.2.25 2350.- 2118.- 1853.-

λ/4 version cemented with cover plates

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 6.4.10 592.- 550.- 501.-
RAC 6.4.15 951.- 873.- 784.-
RAC 6.4.20 1541.- 1404.- 1248.-
RAC 6.4.25 2350.- 2118.- 1853.-

λ/2 version with air gap

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 6.2.10L 715.- 664.- 606.-
RAC 6.2.15L 1166.- 1071.- 961.-
RAC 6.2.20L 1874.- 1708.- 1517.-
RAC 6.2.25L 2681.- 2416.- 2114.-

λ/4 version with air gap

order no. 1 piece in € 2-5 piece in € 6-10 piece in €
RAC 6.4.10L 715.- 664.- 606.-
RAC 6.4.15L 1166.- 1071.- 961.-
RAC 6.4.20L 1874.- 1708.- 1517.-
RAC 6.4.25L 2681.- 2416.- 2114.-
adaptor for mount diameters 30mm and 40 mm adaptor ring mount
connection with Thorlabs SM1 or SM2 thread on request
other sizes (up to 100 mm) on request
unmounted plates on request
other spectral ranges on request