Empty Glass Cells with Textured Antireflective Flat Windows

  • 20 mm Long Empty Glass Cells with Ø1/2" Textured Windows or 50 mm Long Empty Glass Cells with Ø1" Textured Windows
  • Antireflective UV Fused Silica or Infrasil®* Textured Windows
  • Custom Solutions Available


Ø1/2" UVFS Textured Window
20 mm Cell Length


Ø1" Infrasil®* Textured Window
50 mm Cell Length

Textured antireflective windows minimize glare for enhanced clarity. The zoomed-in view shows an SEM image of a nanostructured UVFS window surface.

*Infrasil® is a registered trademark of Heraeus Quarzglas.

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Inside Thorlabs: Scientific Glassblowing
Textured Glass Cell
Click to Enlarge

Textured Windows Seal Off the Empty Cell and Minimize Glare
Item # GC20T1 GC20T2 GC50T1 GC50T2
Cell Lengtha 20.0 ± 3.0 mm 50.0 ± 3.0 mm
Path Lengthb 18.0 ± 3.0 mm 48.0 ± 3.0 mm
Cell Outer Diameter 12.7 ± 0.2 mm 25.0 ± 0.2 mm
Cell Clear Aperture >Ø8.0 mm >Ø20.0 mm
Textured Window Wavelength Range 400 - 1100 nm 1000 - 1700 nm 400 - 1100 nm 1000 - 1700 nm
Pressure <10-7 Torr to 5 psi at 25 °C
Fill Tube Length 90.0 mm
Fill Tube Outer Diameter 6.4 mm (0.25")
Fill Tube Inner Diameter 4.0 mm (0.16")
Window Angle 0° ± 1.0°
Window Item # W40510T1 WGN051T2 W41010T1 WGN101T2
Window Flatness λ
Window Material UV Fused Silicac Infrasil® 302 UV Fused Silicac Infrasil® 302
Cell Substrate Fused Silica
Reflectanced Ravg < 0.25% Over Wavelength Range
Reflectance Data
(Click for Plot)d

Raw Data

Raw Data

Raw Data

Raw Data
Transmissione Tabs ≥ 98% Over Wavelength Range
Transmission Data
(Click for Plot)e

Raw Data

Raw Data

Raw Data

Raw Data
Diagram (Click to View)
  • Length of the Center of the Cell Including the Windows
  • Length of the Center of the Cell Excluding the Windows
  • Click the link for detailed specifications on the substrate.
  • Per Surface
  • Transmission Through One Window


  • Glass Cells with Textured Antireflective Windows for Spectroscopy Applications:
    • 20 mm Cell Length with Ø1/2" Windows
    • 50 mm Cell Length with Ø1" Windows
  • Two Textured Window Options Available:
    • UV Fused Silica for 400 to 1100 nm
    • Infrasil for 1000 to 1700 nm
  • Fused Silica Cell Substrate
  • Available with One Ø1/4" Fill Tube
  • Custom Design and Manufacturing Services Available (Contact Tech Support)
  • Compatible with a Variety of our Glass Cell Heaters (See Mounting & Heating Options Below)

Thorlabs' Empty Glass Cells with UV Fused Silica (UVFS) or Infrasil®† Textured Broadband Antireflective Flat Windows provide high transmission (≥98% through each window) from 400 to 1100 nm or 1000 to 1700 nm, respectively (see the table to the lower right for transmission graphs). The structured surfaces of the windows have <0.25% reflectance per surface over the wavelength range for reduced glare (see the table to the lower right for reflectance graphs). With their secure hermetic sealing on both ends, these glass cells can protect delicate samples from contamination and ensure reliable performance over time. We also offer a variety of other empty cells for various spectroscopic applications as shown in the selection guide below.

Each cell is made from fused silica, a rugged material known to resist chipping and cracking. All glass cells on this page can hold a vacuum below 10-7 Torr and withstand pressure up to 5 psi. The post-production cleaning process for these cells consists of an ultrasonic cleaning followed by a methanol rinse. The cell is then connected to a vacuum system and leak tested. The cells are not vacuum sealed when shipped; before using the cell in a vacuum setup, we advise users to follow a similar cleaning process for each cell.

Cells are available with one fill tube which is useful when introducing a sample into the cell and sealing it off for measurements. These fill tubes have a 1/4" outer diameter and are compatible with Ø1/4" compression fittings, such as those found on our KF16C025 and KF25C025 KF-Flange Adapters; for more information see the Vacuum Seal tab. As shown in the video to the top right, custom reference cells can be manufactured upon request, including different cell lengths, cell diameters, or fill tube configurations. Please contact Tech Support with inquiries.

These cells are commonly used in absorption spectroscopy; refer to the Application tab for a general overview of use with absorption spectroscopy. We also offer compact and Herriott multipass cells for gas absorption spectroscopy applications, as well as filled and sealed vapor and acetylene reference cells.

Mounting & Heating Options
The glass cells can be mounted in our V-Clamp Mounts, which are available in standard, kinematic, or Ø1.5" post-compatible versions. Please check that the cell diameter is supported by the mount. The VBC2(/M) Post-Mountable Band Clamp can be used to mount the Ø1" glass cells without marring.

Our HT10K and TLK-H Resistive Foil Heaters can attach to the outside of all the glass cells via adhesive backing. Cells with Ø1" windows can be mounted in our GCH25-75 Glass Cell Heater; this requires swapping out the included Ø6 mm cage rods with four ER2 2" long cage rods. We also offer the GCH25R Cap Heater for cells with Ø1" windows. This heater attaches directly to the end of a cell.

Handling Precautions and Cleaning
Thorlabs' Textured Windows could be contaminated or damaged by moisture, fingerprints, aerosols, or contact with any abrasive material; take precautions to avoid direct contact with the windows. Latex gloves or a similar protective covering should be worn to prevent oil from fingers from reaching the structured surface.

If the surface is comtaminated, the windows may be cleaned by:

  • Blowing off dust with clean air or nitrogen.
  • Rinsing with solvents, such as isopropyl alcohol, followed by clean air or nitrogen blow-drying.
  • Immersing in a basic solution (a mix of ammonium hydroxide and hydrogen peroxide) and/or an acid solution (a mix of hydrogen chloride and hydrogen peroxide) followed by clean air or nitrogen blow-drying.

Standard cleaning methods will result in further contamination and thus should be avoided.

†Infrasil is a registered trademark of Heraeus Quarzglas.

Absorption Spectroscopy

The reference substance pumped into the glass cell is associated with a unique absorption spectrum that serves as its fingerprint. The contents of a reference cell can be determined via a linear absorption measurement (as depicted by the simplified schematic below). By scanning a tunable diode laser over a wavelength range and detecting light absorption with a photodetector, a series of peaks will be recorded, which is characteristic of the vapor inside the cell. Please note that we also offer pre-filled and sealed acetylene reference cells, as well as vapor reference cells with quartz or borosilicate substrates.

Reference Cell Setup
Click for Details

Disassembled view of a KF25
flange-to-compression-fitting adapter.

Creating a Vacuum Seal with a KF Flange

Thorlabs' empty glass cells can be used with our KF16 and KF25 Flanged Components and Accessories in order to manage gas flow in and out of the cell. Any glass cells that are terminated with one Ø0.25" (Ø6.35 mm) fill tube can be inserted into the KF16C025 or KF25C025 Flange-to-Compression-Fitting Adapter.

To input the glass cell into a KF16 or KF25 vacuum system, follow the instructions below.

  1. Select a KF16 or KF25 flange-to-compression-fitting adapter that is compatible with the fill tube diameter of the glass cell.
  2. Coat a cleaned and inspected KF16CR-F or KF25CR-F Centering O-Ring in vacuum grease and place it on a base post or pipe.
  3. Place the flange-to-compression-fitting adapter on top of the KF16CR-F or KF25CR-F Centering O-Ring and secure them with the KF16WNC or KF25WNC Wing Nut Clamp.
  4. Loosen and remove the knurled locking knob, O-ring, and seal ring of the flange-to-compression-fitting adapter so its mating surface can be inspected and the included O-ring can be coated in vacuum grease. This will create a vacuum seal when the cell is inserted into the system.
  5. Slide the open end of the glass cell tube through the top (side with the Thorlabs engraving) of the knurled locking knob, seal ring (with the counterbore seat for the O-ring facing the adapter body), and O-ring (in that order) of the flange-to-compression-fitting adapter.
  6. Slide the glass tube into the flange adapter body and then slide the O-ring, seal ring, and knurled locking knob down the tube onto the flange adapter body. Tighten the knurled locking knob by hand.

It is not recommended to insert the glass tube into a fully assembled KF Flange-to-compression-fitting adapter. The sharp edges of the glass tube may damage the O-ring, thus causing the seal to fail. 

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Empty Glass Cells with Textured Windows, One Fill Tube

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
GC20T1 Support Documentation
GC20T1Empty Glass Cell with Ø1/2" UVFS Textured Windows, 20.0 mm Long, One Fill Tube, 400 - 1100 nm
GC20T2 Support Documentation
GC20T2Empty Glass Cell with Ø1/2" Infrasil® Textured Windows, 20.0 mm Long, One Fill Tube, 1000 - 1700 nm
GC50T1 Support Documentation
GC50T1Empty Glass Cell with Ø1" UVFS Textured Windows, 50.0 mm Long, One Fill Tube, 400 - 1100 nm
GC50T2 Support Documentation
GC50T2Empty Glass Cell with Ø1" Infrasil® Textured Windows, 50.0 mm Long, One Fill Tube, 1000 - 1700 nm