Ultra-Stable Non-Polarizing Beamsplitters (NPBS)
Non-Polarizing Beamsplitter (NPBS) is a precision optical component capable of polarization-independent spectroscopy over a wide spectral range. Unlike ordinary beamsplitters, it can maintain the reflectivity and transmittance of S- and P polarized light almost consistently, thereby avoiding energy errors caused by polarization and ensuring a more stable and accurate light intensity distribution.
Feature:
- Polarization neutral design: S and P polarization reflection and transmission are almost equal, and the polarization dependence is <1%.
- Broad spectral suitability: suitable for visible to near-infrared (400–1100 nm), extendable up to 2000 nm.
- High energy stability: typical spectral ratio of 50:50 ±3%, repeatability <2%.
- Low absorption and low scattering: Ion beam sputtering (IBS) dielectric film layer is used, and the absorption loss is <0.5%.
- Multiple structures available: Available in cubic and flat structures, angles and sizes can be customized according to needs.
Applications: laser optical systems, optical measurements, imaging systems, optical communication structures, etc
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Working principle and structure
The non-polarizing eamsplitter distributes energy through the interference effect of multilayer dielectric films. By adjusting the optical thickness and refractive index of the film layer, the reflection curves of S- and P polarized light intersect near the working angle (usually 45°), to obtain the non-polarized characteristics. Common structures include:
- Cube type: composed of two right-angled prisms glued by photosplitting film, with high mechanical stability.
- Flat plate type: The light-splitting film is directly plated on the substrate, and the back is added with AR film, which has a thin and compact structure.
Materials & Manufacturing
- Base material: BK7, UV-grade fused silica, or other precision optical glass.
- Coating process: Ion-assisted deposition (IAD) or ion beam sputtering (IBS) is used, and the film layer is dense and has strong adhesion.
- Assembly method: The cube type uses optical gluing to calibrate the optical axis; The back of the flat plate type is coated with AR coating to reduce reflections.
Manufacturing Tolerances:
- Dimensional tolerances: ±1 mm
- Surface Quality: 40–20 (MIL-PRF-13830B)
- Surface Shape Accuracy: λ/8 (@633 nm)
Applications:
- Laser optical system: used for beam splitting, power sampling, and feedback control.
- Optical metrology and interferometry: Achieve balanced energy distribution and improve measurement accuracy.
- Imaging and Display Systems: For optical path distribution and uniform illumination.
- Spectral analysis and scientific experiments: Achieve polarization-independent signal separation.
- Optical communication module: Realize beam splitting and monitoring in free space and optical fiber systems.
Design considerations
- Angle of incidence selection: The standard design is 45°, and the special angle can be re-optimized for the film structure.
- Band matching: Different bands (UV, VIS, NIR) require specific material combinations.
- Thermal and environmental stability: IBS coatings have excellent humidity and temperature resistance.
- System assembly: The beam offset is generally <3′ to ensure the accuracy of the optical path.
Why Hobbite NPBS
Hobbite has more than 20 years of experience in optical manufacturing, focusing on the R&D and mass production of high-precision custom optical components. Our non-polarized beamsplitters use high-stability optical coating technology to ensure stable and repeatable optical performance in laser optics, imaging systems, and optical metrology. Whether it’s standard 50:50 splitting or custom band and power-bearing designs, Hobbite can provide you with reliable, polarization-neutral optical solutions.
Core Optical Properties
Items | Typical Specifications | Technical Highlights |
Spectral Ratio (R: T) | 50:50 ±3% (optional 30:70, 70:30) | High stability, repeatability <2% |
Polarization Dependence | <1% | Suitable for polarization-sensitive measurements |
Wavelength Range | 400–1100 nm (expandable to 250–2000 nm) | Covers common laser source bands |
Angle of Incidence | 45° (customizable) | Minimal beam deviation |
Total Loss (Absorption + Scattering) | <0.5% | Ion-beam sputtered multilayer coating with low absorption design |
Laser Damage Threshold | >5 J/cm² @1064 nm | Suitable for medium-power laser systems |
Surface Flatness | λ/8 | Extremely low wavefront distortion |
Surface Quality | 40–20 | Meets interferometric-grade optical requirements |
Substrate Material | BK7 / Fused Silica | High transmittance and thermal stability |
Clear Aperture | >90% | Ensures high light efficiency transmission |
Size Range | 5–50 mm | Available in various sizes and mounting customizations |
