This page displays window transmission curves for several of the windows Janis Research offers for our cryostats.  Please consult with a sales engineer to determine which materials are right for your cryostat and experiment requirements.

Thank you to ISP Optics for providing curves for their uncoated windows.

Thank you to Tydex Optics for providing curves for their windows for THz use (shown at the bottom of the page).

Window Transmission Curves

  • Amtir-1 (Amorphous Material

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of AMTIR-1 Amorphous Material transmission curve.

    Click here for the Amtir-1 (Amorphous Material) datasheet. (PDF)

  • Barium Fluoride (BaF2)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Barium Fluoride (BaF2) window transmission curve.

    Click here for the Barium Fluoride (BaF2) datasheet. (PDF)

  • Caesium Iodide (CsI)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Caesium Iodide (CsI) window transmission curve.

    Click here for the Caesium Iodide (CsI) datasheet. (PDF)

  • Cadmium Telluride (CdTe)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Cadmium Telluride (CdTe) window transmission curve.

    Click here for the Cadmium Telluride (CdTe) datasheet. (PDF)

  • Calcium Fluoride (CaF2)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Calcium Fluoride (CaF2) window transmission curve.

    Click here for the Calcium Fluoride (CaF2) datasheet. (PDF)

  • Gallium Arsenide (GaAs)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Gallium Arsenide (GaAs) window transmission curve.

    Click here for the Gallium Arsenide (GaAs) datasheet. (PDF)

  • Fused Silica UV grade (SiO2)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Fused Silica UV Grade (SiO2) window transmission curve.

    Click here for the Fused Silica UV Grade (SiO2) datasheet. (PDF)

  • Fused Silica IR grade (SiO2)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Fused Silica IR Grade (SiO2) window transmission curve.

    Click here for Fused Silica IR Grade (SiO2) datasheet. (PDF)

  • Quartz crystalline (SiO2)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Quartz crystalline (SiO2) window transmission curve.

    Click here for Quartz crystalline (SiO2) datasheet. (PDF)
    PLEASE NOTE: Crystal Quartz windows are provided in random orientation by default. Z-cut Crystal Quartz is available by special request.

  • Magnesium Fluoride (MgF2)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Magnesium Fluoride (MgF2) window transmission curve.

    Click here for Magnesium Fluoride (MgF2) datasheet. (PDF)

  • Potassium Bromide (KBr)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Potassium Bromide (KBr) window transmission curve.

    Click here for Potassium Bromide (KBr) datasheet. (PDF)

  • Potassium Chloride (KCl)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Potassium Chloride (KCl) window transmission curve.

    Click here for Potassium Chloride (KCl) datasheet. (PDF)

  • Sapphire (Al2O3)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Sapphire (Al2O3) window transmission curve.

    Click here for Sapphire (Al2O3) datasheet. (PDF)
    PLEASE NOTE: Sapphire windows are provided in random orientation by default. C-cut Sapphire is available by special request.

  • Silicon (Si)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Silicon (Si) window transmission curve.

    Click here for the Silicon (Si) datasheet. (PDF)

  • Thallium-Bromoiodide (KRS-5)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Thallium Bromoiodide KRS-5 (TlBr-Tll) window transmission curve.

    Click here for the Thallium-Bromoiodide (KRS-5) datasheet. (PDF)

  • Zinc Selenide (ZnSe CVD)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Zinc Selenide (ZnSe CVD) window transmission curve.

    Click here for the Zinc Selenide Laser Grade (ZnSe CVD) datasheet. (PDF)

  • Zinc Sulfide (ZnS Cleartran)

    Window transmission curves provided by ISP Optics.

    Click image to enlarge view of Zinc Sulfide Cleartran, ZnS, window transmission curve.

    Click here for the Zinc Sulfide (ZnS Cleartran®) datasheet. (PDF)

From the Tydex web site:

THz components

Terahertz (THz) radiation is located in the spectral region ~0.1-10 THz (~3 mm - 30 μm, 3 cm-1 - 300 cm-1) between the microwave and mid infrared range of the electromagnetic spectrum. 

Below we introduce transmission spectra and other properties of materials put to use for THz optics production. Measurements in THz region were made at ABB FTIR spectrometer Bomem DA3 and Bruker IFS 125HR (measure of inaccuracy is 2-3% below 100 µm and 4-5% over 100 µm). Measurements in near infrared range were made at Perkin Elmer “Lambda- 9” (measure of inaccuracy < 0.5%).  

As you can see, all organic materials like TPX, PE, and PP have uniform stable transmission about 80-90% starting from ~200 µm and up to 1000 µm. Surely they excellently transmit at larger wavelengths too.

Crystalline materials like silicon, quartz, and sapphire have lower transmission in THz range due to reflection losses.

Transmission Spectra for THz Window Materials

  • 1. Polymers

    From the Tydex web site:

    Among large variety of available polymers there are some of excellent terahertz transparencies with relatively low reflectivity. The best materials in this sense are TPX (polymethylpentene), polyethylene (PE), polypropylene (PP).

  • 1.1 Polymethylpentene (TPX)

    From the Tydex web site:

    TPX is the lightest of all known polymers. It is optically transparent in UV, visible, and THz ranges.

    Transmission of TPX 2 mm-thick sample. THz region. Courtesy of Tydex.
    Fig. 1 Transmission of TPX 2 mm-thick sample. THz region.

    Transmission of TPX 2 mm-thick sample. NIR and MIR regions. Courtesy of Tydex.
    Fig. 2 Transmission of TPX 2 mm-thick sample. NIR & MIR regions.

    Transmission of TPX 2 mm-thick sample. UV and VIS and NIR ranges. Courtesy of Tydex.

    Fig. 3 Transmission of TPX 2 mm-thick sample.  UV & VIS & NIR ranges.

    Material TPX
    Available diameters, mm to 100
    Diameter tolerance, mm ±0.25
    Thickness tolerance 2% of thickness but not more than 0.1 mm
    Surface quality, scr/dig 80/50
    Surface accuracy, λ@30µm 1/3

    Transmission of 2 mm thick samples of TPX, Picarin, and HDPE. Courtesy of Tydex.
    Fig. 4 Transmission of 2 mm-thick samples of TPX, Picarin, and HDPE.

  • 1.2 Polyethylene (PE)

    From the Tydex web site:

    Transmission of 2 mm-thick HDPE sample. THz region. Courtesy of Tydex.
    Fig. 5 Transmission of 2 mm-thick HDPE sample. THz region.

    Transmission of 2 mm-thick HDPE sample. NIR & MIR region. Courtesy of Tydex.
    Fig. 6 Transmission of 2 mm-thick HDPE sample.  NIR & MIR region.

    Unfortunately, HDPE transmission in visible region is very poor.

    Transmission of 2 mm-thick HDPE sample. VIS and NIR region. Courtesy of Tydex.
    Fig. 7 Transmission of 2 mm-thick HDPE sample.  VIS & NIR region.

    Material HDPE
    Available diameters, mm to 100
    Dimensions tolerance, mm ±0.25
    Clear aperture, % ≥90
    Surface quality, scr/dig 80/50

  • 1.3 Polypropylene (PP)

    From the Tydex web site:

    Transmission of polypropylene 2.0 mm-thick sample. THz region. Courtesy of Tydex.
    Fig. 8 Transmission of polypropylene 2.0 mm-thick sample. THz region.

    Transmission of polypropylene 2.0 mm-thick sample. NIR and MIR region. Courtesy of Tydex.
    Fig. 9 Transmission of polypropylene 2.0 mm-thick sample. NIR & MIR region.

    Transmission of polypropylene 2.0 mm-thick sample. VIS and NIR region. Courtesy of Tydex.
    Fig. 10 Transmission of polypropylene 2.0 mm-thick sample. VIS & NIR region.

  • 2.1 Crystal quartz

    From the Tydex web site:

    One of the best materials for wavelengths above 50 µm is z-cut crystal quartz. It is important that z-cut crystal quartz windows are transparent in the visible range allowing easy adjustment with HeNe laser, do not change the state of light polarization, and can be cooled down below the λ-point of liquid helium.  PLEASE NOTE: Crystal Quartz windows are provided in random orientation by default. Z-cut Crystal Quartz is available by special request. 

    Transmission of crystal quartz 1.0 mm thick. Courtesy of Tydex.
    Fig. 13 Transmission of crystal quartz 1.0 mm-thick.

    Crystal quartz is birefringent material that should be taken into account if the polarization of radiation is of importance.

    Material THz grade crystal quartz
    Orientation Z-cut*
    Dimensions tolerance, mm ±0.25
    Clear aperture, % ≥90
    Parallelism, arc. min. 5
    Surface quality, scr/dig 60/40

    * Crystal Quartz windows are provided in random orientation by default. Z-cut Crystal Quartz is available by special request.

  • 2.2 Sapphire

    From the Tydex web site:

    Sapphire like crystalline quartz is transparent in THz region as well as in visible one. As can be seen from below spectra transmission doesn't depend on crystal orientation within measure of inaccuracy.  PLEASE NOTE: Sapphire windows are provided in random orientation by default. C-cut Sapphire is available by special request.

    Transmission of sapphire samples with different thickness. Samples of various crystallographic orientations were measured. Courtesy of Tydex.
    Fig. 14 Transmission of sapphire samples with different thickness.  Samples of various crystallographic orientations were measured.

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