Product Description
75mm Diameter 50/50 Plate Beam Splitter – High-Precision Optic
This is a high-quality circular plate beam splitter, measuring 75mm in diameter and 11.5mm thick, ideal for visible wavelength applications. Crafted from N-BK7 borosilicate crown glass, it offers excellent optical homogeneity, high transmission in the 400–700nm range, and good thermal stability for demanding setups .
N-BK7 is the most common optical glass for precision optics, offering an excellent combination of optical performance, mechanical durability, and cost-effectiveness . Its high homogeneity ensures minimal wavefront distortion, critical for laser and imaging applications.
Key Specifications
| Specification | Details |
|---|---|
| Diameter | 75 mm |
| Thickness | 11.5 mm (enhanced rigidity) |
| Substrate Material | N-BK7 borosilicate crown glass |
| Surface Flatness | λ/10 @ 632.8 nm over clear aperture |
| Clear Aperture | >80% of central area |
| Front Surface | Multilayer dielectric beam-splitting coating; 50/50 R/T ratio |
| Back Surface | Broadband anti-reflection (AR) coating |
| AR Performance | <1% reflection per surface in VIS range |
| Edge Markings | λ/10 and A/R (indicating AR-coated side) |
| Wavelength Range | Visible (400–700 nm) |
| Angle of Incidence | Suitable for 0°–45° operation |
| Condition | Good optical condition; no scratches or chips |
| Edge Finish | Ground/polished for safe handling |
Material Advantages – N-BK7
N-BK7 (borosilicate crown glass) is the industry standard for general-purpose precision optics :
| Property | Value / Benefit |
|---|---|
| Transmission Range | 350 nm – 2.5 μm |
| Refractive Index | 1.5168 @ 587.6 nm |
| Thermal Expansion | 7.1 x 10⁻⁶ K⁻¹ |
| Thermal Conductivity | 1.114 W m⁻¹ K⁻¹ |
| Density | 2.51 g/cm³ |
| Chemical Resistance | Strong resistance; durable surface finish |
N-BK7 provides excellent homogeneity, low bubble and inclusion content, and straightforward manufacturability, making it a top choice for transmissive optics .
Coating Technology & Performance
Front Surface: Dielectric Multilayer 50/50 Beamsplitter Coating
-
Designed for equal splitting of incident light (50% reflection / 50% transmission)
-
Dielectric coatings offer superior durability and lower absorption compared to metallic coatings
-
Optimized for visible wavelengths (400–700 nm)
Back Surface: Broadband Anti-Reflection (AR) Coating
-
Reduces unwanted reflections to <1% per surface
-
Minimizes ghosting and interference effects
-
Improves overall system throughput
Polarization Effects (for reference at 45° incidence):
-
S-polarized light: approximately 50/50 split
-
P-polarized light: approximately 30/70 split
-
Unpolarized light: approximately 40/60 average split
Surface Flatness: λ/10
-
λ/10 flatness ensures minimal wavefront distortion for precision applications
-
Comparable to precision-grade beamsplitters from major manufacturers
Enhanced Rigidity – 11.5mm Thickness
This beamsplitter’s 11.5mm thickness is significantly thicker than standard plate beamsplitters (typically 1–5mm). This provides:
-
Enhanced mechanical rigidity for robust assemblies
-
Reduced beam offset at angled incidence (e.g., 45°)
-
Minimal flexure under mounting stress
-
Improved thermal stability in varying environments
Applications
Laser Setups:
-
Beam combining and power monitoring
-
Beam sampling for feedback control
-
Interferometry and holography
Interferometry and Metrology:
-
λ/10 flatness minimizes measurement errors
-
Ideal for precision optical testing
Microscopy and Imaging:
-
Fluorescence microscopy (excitation/emission separation)
-
Brightfield splitting for dual-channel imaging
-
Beam routing in confocal systems
Photonics Research:
-
Optical prototyping and experiment setups
-
Educational laboratories
-
DIY optics projects
Edge Markings
The optic is marked with “λ/10” and “A/R” on the edge:
-
A/R indicates the anti-reflection coated side
-
This marking ensures proper orientation during installation
-
Following the arrow direction (if present) helps identify the coated surfaces
Condition
GOOD OPTICAL CONDITION
NO VISIBLE SCRATCHES OR CHIPS
SURFACES CLEAN, COATINGS INTACT
EDGES GROUND/POLISHED FOR SAFE HANDLING
READY FOR INTEGRATION
⚠ HANDLING NOTE: This is a precision optical component with delicate dielectric coatings. Handle only by edges with clean gloves. Never touch coated surfaces. Store in clean, dry environment when not in use.



