Precision Flat Optical Windows with or without AR Coatings

Optical windows provide protection between an optical system or sensitive electronics and an outside environment. It is important to select a window that transmits the wavelengths used in the system. In addition the substrate material should be able to withstand the environmental conditions of the application. Windows are useful for protecting a laser output from environmental effects and for beam sampling applications. We offer Windows in a wide range of substrates, sizes and thicknesses to meet any application need.

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Paralight Optics offers both standard and high precision optical flat windows fabricated from various substrate materials for use in a large variety of laser and industrial applications. Our substrates include N-BK7, UV Fused Silica (UVFS), Sapphire, Calcium Fluoride, Magnesium Fluoride, Potassium Bromide, Infrasil, Zinc Selenide, Silicon, Germanium, or Barium Fluoride. Our laser windows have a wavelength-specific AR coating centered around commonly used laser wavelengths and an optional wedge, while our precision windows are offered with or without a broadband AR coating providing good optical performance for angles of incidence (AOI) between 0° and 30°.

Here we list Calcium Fluoride Flat Window. Calcium fluoride has a low absorption coefficient and high damage threshold, making these windows a good choice for use with free-space lasers. Our calcium fluoride (CaF₂) High-Precision Flat Windows either uncoated or with a broadband anti-reflective coating. The uncoated windows provide high transmission from the ultraviolet (180 nm) to the infrared (8 μm). The AR-coated windows feature an antireflection coating on both sides that provides increased transmission within the 1.65 – 3.0 µm specified wavelength range. Given its low absorption coefficient and high damage threshold, uncoated calcium fluoride crystal is a popular choice for use with excimer lasers. CaF₂ windows are also commonly used in cryogenically cooled thermal imaging systems. Please check the following graphs for your references.

Features:

Material Options:

See the following flat windows selection

Wavelength Range:

as the requirements

Coating Options:

Available Either Uncoated or AR Coated as Request

Custom Options:

Different Designs, Sizes and Thickness Available

Common Specifications:

pro-related-ico — This left form is windows selection general guide for your references.

Parameters

Ranges & Tolerances

Substrate Material

N-BK7 (CDGM H-K9L), UV fused silica (JGS 1) or other IR materials
Type

Standard Flat Window (round, square, etc.)
Size

Custom-made
Size Tolerance

Typical: +0.00/-0.20mm | Precision: +0.00/-0.10mm
Thickness

Custom-made
Thickness Tolerance

Typical: +/-0.20mm | Precision: +/-0.10mm
Clear Aperture

>90%
Parallelism

Uncoated: ≤ 10 arcsec | AR Coated: ≤ 30 arcsec
Surface Quality (Scratch - Dig)

Precision: 40-20 | High Precision: 20-10
Surface Flatness @ 633 nm

Typical: ≤ λ/4 | Precision: ≤ λ/10
Transmitted Wavefront Error @ 633 nm

Uncoated: ≤ λ/10 per 25mm | AR Coated: ≤ λ/8 per 25mm
Chamfer

Protected: < 0.5mm x 45°
Coating

Narrow Band: Ravg < 0.25% per surface at 0° AOI
Broad Band: Ravg < 0.5% per surface at 0° AOI
Laser Damage Threshold

UVFS: >10 J/cm² (20ns, 20Hz, @1064nm)
Other Substrate: >5 J/cm^{2 (20ns, 20Hz, @1064nm)}