ART Photonics FOCO-L-3/5-F20 Mid-Infrared Fiber Collimator with ZnSe Lens (3–5 µm, f = 20 mm)

Overview

The ART Photonics FOCO-L-3/5-F20 is a precision-engineered mid-infrared (MIR) fiber collimator designed for stable, low-aberration beam expansion and collimation in the 3–5 µm spectral window. It integrates a high-transmission, anti-reflection coated zinc selenide (ZnSe) aspheric lens with a kinematically aligned, hermetically sealed fiber ferrule assembly—optimized for compatibility with fluoride, chalcogenide, or hollow-core MIR fibers (e.g., InF₃, As₂S₃, or Kagome-type). Based on paraxial Gaussian beam optics and diffraction-limited collimation design principles, the FOCO-L-3/5-F20 delivers consistent beam divergence control (< ±0.15 mrad typical), minimal wavefront error (< λ/8 @ 4.26 µm), and high pointing stability under thermal cycling (−10 °C to +60 °C). Its modular stainless-steel housing ensures mechanical rigidity and compatibility with standard optomechanical mounts (SM1-threaded, Ø1", or kinematic baseplates), making it suitable for integration into FTIR spectrometers, quantum cascade laser (QCL) beam delivery paths, and standoff chemical detection platforms.

Key Features

• Zinc selenide (ZnSe) lens with broadband AR coating optimized for 3–5 µm transmission (>95% per surface)
• Focal length precisely calibrated to 20 mm ±0.05 mm at 4.26 µm reference wavelength
• Integrated FC/PC or SMA-905 fiber interface with 50–200 µm core diameter support (customizable)
• Hermetic sealing and inert-gas purging option available for moisture-sensitive ZnSe operation
• Thermally compensated lens mount minimizing focal shift across operational temperature range
• Alignment-free factory collimation: collimated output beam waist located at infinity within ±1% tolerance
• Compliant with ISO 10110-7 surface quality specifications (scratch-dig 20–10) and MIL-PRF-13830B inspection standards

Sample Compatibility & Compliance

The FOCO-L-3/5-F20 is compatible with single-mode and multimode mid-IR optical fibers operating in the 3–5 µm band—including step-index fluorozirconate (ZBLAN), tellurite, and polycrystalline silver halide (AgCl_xBr_1−x) fibers. It supports common fiber outer diameters (OD): 0.9 mm, 1.6 mm, and 2.3 mm jacketed configurations. The device conforms to IEC 61300-2-4 (fiber optic connector durability), IEC 61300-2-1 (tensile load testing), and RoHS 2015/863/EU material restrictions. For regulated laboratory environments, its mechanical and optical performance remains traceable to NIST-traceable interferometric calibration reports (available upon request), supporting GLP-compliant documentation workflows.

Software & Data Management

While the FOCO-L-3/5-F20 is a passive optical component requiring no firmware or driver software, ART Photonics provides full metrological documentation including: (i) individual collimation test reports with measured beam profile (M² < 1.1), divergence, and centroid stability; (ii) spectral transmittance curves (3–5 µm, 2 cm⁻¹ resolution); and (iii) mechanical drawings with GD&T annotations compliant with ASME Y14.5–2018. All reports are delivered in PDF/A-1b format and include digital signatures for audit readiness. Optional integration with LabVIEW™ or Python-based alignment monitoring scripts is supported via third-party beam profiling cameras (e.g., Gentec-EO Pyrocam IV or Ophir Pyroelectric sensors).

Applications

• Collimated free-space coupling of QCLs and interband cascade lasers (ICLs) into multipass gas cells for trace gas analysis (e.g., CO, NO, CH₄, NH₃)
• Beam conditioning for Fourier-transform infrared (FTIR) spectrometers using MCT or InSb detectors
• Optical front-end modules in industrial process analyzers compliant with ISA-84 SIL-2 functional safety requirements
• Mid-IR optical coherence tomography (MIR-OCT) probe arms requiring diffraction-limited spot stability
• Free-space interconnection between cryogenic MIR detectors and room-temperature fiber sources
• Calibration reference collimators in national metrology institutes for MIR radiometry traceability

FAQ

Is the ZnSe lens susceptible to humidity-induced degradation?
Yes—ZnSe is hygroscopic. The FOCO-L-3/5-F20 includes optional nitrogen-purged housing with O-ring seals (IP54 rated) to mitigate surface oxidation; recommended for continuous operation in RH > 60% environments.
Can this collimator be used with pulsed MIR lasers?
Yes—tested up to 10 MW/cm² peak power density at 4.5 µm, 10 ns pulses; damage threshold verified per ISO 21254-1:2018.
What fiber types are validated for use with this collimator?
Factory-tested with Thorlabs FG-IR100-200, Le Verre Fluoré IR-F1000, and Art Photonics IRflex-200 fibers; custom alignment for non-standard fibers available under NDA.
Is recalibration required after mechanical shock or thermal cycling?
No—mechanical design incorporates stress-relieved lens mounting and zero-backlash kinematic interfaces; verified over 500 thermal cycles (−40 °C ↔ +85 °C) without collimation drift exceeding ±0.03 mrad.
Do you provide ISO/IEC 17025-accredited calibration certificates?
Yes—upon request, accredited calibration (by DAkkS-certified lab) includes beam parameter measurement uncertainty budgets per EURAMET cg-18/v.02 guidelines.