Custom Barium Fluoride

BBAR coated windows Barium fluoride (BaF₂) is a crystalline compound with excellent transmission of over 90% between 0.2 to 10µm, so can be used in applications working in vacuum ultraviolet as well as longwave infrared. Compared to the other fluoride materials, BaF2 is resistant to high-energy radiation, including gamma and x-rays.

Below is a brief summary of barium fluoride’s optical properties, a full data sheet is available here.

Transmission range	0.15 to 12µm
Refractive Index	1.45 @ 5µm
Density	4.89 g/cm³
Melting Point	1386°C
Hardness	Knoop 82 with 500g indenter
Operating temperature	< 800°C in dry environment

Knight Optical can supply a variety of barium fluoride optical components including windows, lenses, prisms and BaF2 blanks. We can also provide uncoated and coated optics, with broadband antireflective (BBAR) coatings designed to enhance the optics performance at certain wavebands.. Our typical manufacturing specifications are listed below, however we are always expanding our capabilities so if your requirements are not mentioned below please contact our technical sales team who will guide you through your enquiry.

Diameter	Windows: < 5mm to 200mm Lenses: < 5mm to 60mm+
Form error (@633nm)	< 0.25 waves
Centration /parallelism	< 1 arc minute
Scratch/dig	< 60/40
Typical coatings	Single sided BBAR @ 2-10µm

Uncoated, 1mm thick

With our in-house state-of-the-art metrology laboratory you can be confident that your optical components will meet your requirements. You can find out more about our testing facilities here.

BaF2 window capabilities
BaF2 spherical lens capabilities
BaF2 prism capabilities
BaF2 ground blank capabilities

Optical material Infrared Barium fluoride

Barium Fluoride Windows

Considerations

Barium fluoride is a hazardous material and precautions should be taken when handling, you can find our barium fluoride SDS here.
In a dry environment it can be used up to 800°C.
When exposed to moisture, BaF₂ degrades at 500°C, especially its performance in the vacuum ultraviolet (VUV) range.

Typical Applications

Scintillator Crystal

BaF₂ is the fastest known scintillator material, and therefore is used to produce fast-acting, radiation resistant scintillation detectors used to detect x-ray and gamma rays by converting this high-energy radiation into lower energy photons which are emitted in the UV bands centred at 195nm and 220nm.
Barium fluoride scintillators also emit at a slower rate at 310nm. BaF₂scintillators are used for Positron Emission Tomography (PET) and nuclear physics applications.

FTIR Spectroscopy

Due to barium fluorides impressive transmission range from 200nm up to 12 micron, it is well suited for use in FTIR spectrometers. Knight Optical can provide stock and custom standard or drilled BaF₂ cell windows.

Thermography

Barium fluoride viewports are often used in IR thermography due to their transmission in the MWIR and LWIR wavebands.

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