WP25H-C

• CaF₂ substrate for excellent transmission in the infrared region.
• Holographic wire-grid polarizer designed for broadband IR polarization applications.
• Ø25 mm (1") optic for integration into standard optical systems.
• Ø18 mm clear aperture provides a large usable optical area.
• Provides high polarization selectivity across a broad infrared wavelength range.
• Typical extinction ratio: approximately 100:1 at 3 µm and 250:1 at 8 µm.
• Mounted configuration provides convenient handling and integration into optical setups.
• Suitable for applications requiring linear polarization control and analysis in the mid-IR.
• Available as part of Thorlabs' family of holographic wire-grid polarizers using different IR-transparent substrates.

The Thorlabs WP25H-C is a Ø25 mm CaF₂ holographic wire-grid polarizer designed for controlling and analyzing the polarization state of infrared radiation.

The polarizer uses a holographically produced wire-grid structure to selectively transmit one linear polarization component while attenuating the orthogonal polarization. This makes it particularly useful for broadband infrared applications where conventional visible-wavelength polarizers may not provide suitable transmission or operating bandwidth.

The calcium fluoride (CaF₂) substrate provides excellent infrared transmission and is well suited for applications involving wavelengths extending into the mid-infrared region. Thorlabs specifies typical extinction ratios of approximately 100:1 at 3 µm and 250:1 at 8 µm, demonstrating its ability to discriminate between orthogonal polarization states across the IR spectrum.

The optic has a 25 mm outer diameter and 18 mm clear aperture, and the polarizer is supplied in a mounted configuration for convenient installation in laboratory optical systems. Thorlabs lists the WP25H-C as a CaF₂ Holographic Wire-Grid Polarizer, Mounted.

Compared with standard visible/NIR linear polarizers, the WP25H-C is especially advantageous for infrared spectroscopy, thermal imaging, IR laser systems, and polarization-sensitive measurements.

Product Type: Holographic Wire-Grid Polarizer
Part Number: WP25H-C
Polarizer Type: Holographic Wire-Grid
Substrate Material: Calcium Fluoride (CaF₂)
Optic Diameter: 25.0 mm (Ø1")
Clear Aperture: Ø18 mm
Mounting: Mounted
Typical Extinction Ratio at 3 µm: 100:1
Typical Extinction Ratio at 8 µm: 250:1
Operating Region: Infrared/Mid-IR
Polarization: Linear
Outer Mount Diameter: Ø25 mm

The extinction-ratio values above are typical values reported by Thorlabs rather than a single guaranteed value across the complete operating range. Thorlabs lists the CaF₂ version at approximately 100:1 at 3 µm and 250:1 at 8 µm.

The WP25H-C is suitable for a wide range of infrared polarization applications, including:

• Mid-IR Polarization Control
• Infrared Spectroscopy
• IR Laser Systems
• Thermal Imaging
• Infrared Imaging Systems
• Polarization Analysis
• IR Optical Measurements
• Fourier Transform Infrared (FTIR) Systems
• Remote Sensing
• Gas Detection and Spectroscopy
• Infrared Microscopy
• Scientific and Research Optical Systems
• Polarization-Sensitive Detection
• Free-Space Infrared Optical Systems

The WP25H-C is particularly suitable when an experiment requires broadband linear polarization in the infrared region, especially in systems operating around the 3–8 µm range, where its CaF₂ substrate and wire-grid structure provide useful IR transmission and polarization discrimination.