asphericon ALL50-100-U-U Precision Aspheric Lens (N-BK7, f/d = 2.0)
| Brand | asphericon |
|---|---|
| Origin | Germany |
| Model | ALL50-100-U-U |
| Material | N-BK7 |
| Diameter | 50 mm |
| Effective Focal Length (EFL) | 100 mm |
| f/d Ratio | 2.0 |
| Numerical Aperture (NA) | 0.24 |
| Working Distance (WD) | 93.4 mm |
| Design Wavelength | 780 nm |
| Surface Irregularity (RMSi) | < 100 nm |
| Wavefront RMS | < 51 nm |
| Scratch-Dig | 60–40 |
| Coating | Broadband AR (A/B/C series, optimized for 780 nm) |
Overview
The asphericon ALL50-100-U-U is a high-precision, unmounted N-BK7 aspheric lens engineered for demanding laser beam shaping and collimation applications where diffraction-limited performance and minimal wavefront error are critical. Unlike spherical optics, this aspheric element corrects spherical aberration intrinsically through its non-spherical surface profile—enabling tighter focus spots, higher energy density, and improved coupling efficiency into single-mode fibers or optical cavities. With a fixed focal length of 100 mm and a diameter of 50 mm, the lens maintains an f/d ratio of 2.0—a design parameter carefully selected to balance compactness, depth of field, and angular acceptance in low-to-moderate NA systems. Its surface irregularity (RMSi) is guaranteed below 100 nm, and wavefront error remains under 51 nm RMS at the design wavelength of 780 nm—meeting stringent requirements for ultrafast laser systems, quantum optics setups, and interferometric alignment.
Key Features
- Optimized aspheric surface profile manufactured via deterministic sub-aperture polishing and verified with phase-shifting interferometry (PSI)
- N-BK7 substrate offering high transmission (>99.5% per surface with AR coating), low thermal expansion (7.1 × 10⁻⁶ K⁻¹), and excellent homogeneity (Δn < 5 × 10⁻⁶)
- Broadband anti-reflection coating (A/B/C series) deposited via ion-beam sputtering—achieving average reflectivity < 0.25% across 750–810 nm
- Uncoated edge clearance (U-U designation) ensures compatibility with custom mounting solutions and avoids coating-induced stress birefringence
- Traceable metrology: each lens ships with individual interferometric test report, including Zernike decomposition and PV/RMS wavefront maps
- Compliant with ISO 10110-5:2018 for surface form tolerance and ISO 10110-7:2017 for surface quality specifications
Sample Compatibility & Compliance
The ALL50-100-U-U is compatible with standard Ø50 mm kinematic lens mounts (e.g., Thorlabs SM2-threaded cells, Newport KM100 series) and supports integration into both free-space and fiber-coupled architectures. Its 780 nm design wavelength aligns with Ti:sapphire lasers, diode-pumped solid-state (DPSS) sources, and quantum dot excitation systems. All asphericon aspheres adhere to ISO 9001-certified manufacturing protocols and undergo 100% inspection per MIL-PRF-13830B for scratch-dig (60–40). The lens meets RoHS 2015/863/EU and REACH SVHC compliance standards; no restricted substances are present in substrate or coating layers. Documentation includes full traceability to interferometric calibration standards traceable to PTB (Physikalisch-Technische Bundesanstalt).
Software & Data Management
Asphericon provides native optical design files for immediate integration into industry-standard platforms: Zemax (.zmx), CODE V (.seq), OSLO (.len), VirtualLab Fusion (.vlf), and STEP (.stp) geometry models. These files include accurate surface sag data (up to 36th-order polynomial coefficients), coating dispersion curves (Sellmeier parameters), and thermal expansion behavior. Users may import these directly into tolerance analysis workflows or perform stray-light modeling using built-in scatter models (ABg + Harvey-Shack). All design assets are accessible via secure customer portal with audit-log access control—supporting GLP/GMP-aligned documentation practices where required.
Applications
- Laser beam collimation and focusing in ultrafast amplifier chains (e.g., CPA systems operating at 780 nm)
- High-fidelity illumination optics for confocal microscopy and structured light projection
- Input/output coupling optics for external cavity diode lasers (ECDLs) and tapered amplifier systems
- Alignment reference elements in gravitational wave detector path stabilization subsystems
- Custom relay optics in industrial laser material processing heads requiring stable M² < 1.1 propagation
- Primary focusing elements in compact optical parametric oscillator (OPO) pump cavities
FAQ
What does “U-U” signify in the model number ALL50-100-U-U?
“U-U” indicates an unmounted lens with uncoated edges—ensuring mechanical compatibility with custom cell designs and eliminating edge-coating interference in high-power applications.
Is this lens suitable for femtosecond pulse applications?
Yes—the N-BK7 substrate exhibits negligible group delay dispersion (GDD) at 780 nm (< 5 fs²/mm), and the A/B/C AR coating is optimized for minimal spectral phase distortion across the Ti:sapphire gain bandwidth.
Can I request a custom coating for a different wavelength range?
Yes—asphericon offers tailored broadband or narrowband coatings (e.g., 1030 nm Yb-fiber laser line, 1550 nm telecom band); lead time increases by 4–6 weeks depending on coating stack complexity.
Do you provide mounting recommendations for minimizing stress-induced birefringence?
We recommend low-stress kinematic mounts with compliant polymer gaskets (e.g., Viton® or EPDM) and torque-controlled assembly (max 0.3 N·m for SM2 threads); full mounting guidelines are included in the technical datasheet.
Are Zemax files provided with polarization-dependent performance data?
Yes—each download package includes polarization-sensitive merit functions, Jones matrix evaluation points, and retardance maps calculated over ±5° field angles.
