Synthetic Quartz Capillary Tube — High-UV-Transmittance Fused Silica Capillary, <20 ppb Metallic Impurities
LUMIGLAS® synthetic quartz capillary tube is produced from 6N-grade fused silica with all metallic impurities controlled below 20 ppb (total), verified by ICP-MS analysis. OH hydroxyl content is below 1 ppm. The high UV transmittance and low UV absorption of synthetic fused silica make this capillary the standard substrate for optical fiber preform inner bore tubes, specialty fiber capillary components, photonic crystal fiber and precision UV-grade analytical components. Standard dimensions: OD ≤10 mm, WT ≤1.5 mm, length ≤2000 mm. Custom dimensions available on request.
Description
The LUMIGLAS® synthetic quartz capillary tube is an ultra-fine-bore fused silica tube that Lumistar produces from 6N-grade synthetic fused silica (SiO₂ ≥99.9999%), controlling all metallic impurities below 20 ppb total — verified by ICP-MS analysis. Unlike standard borosilicate or natural fused quartz capillaries, the synthetic fused silica base glass delivers both ultra-low metallic contamination and high UV transmittance with low UV absorption. As a result, engineers specify this capillary as the standard substrate for optical fiber preform inner bore tubes, specialty fiber components and UV-grade analytical instrument applications.
Because the capillary OD is ≤10 mm with wall thickness ≤1.5 mm, Lumistar maintains tight dimensional tolerances throughout — OD tolerance ±0.20 mm and WT tolerance ±0.20 mm at this size class, with out-of-roundness ≤0.08 mm and wall eccentricity ≤0.08 mm. These tolerances support the precise bore concentricity required for fiber preform assembly and micro-optical applications. Moreover, the tube controls OH hydroxyl content below 1 ppm, thereby eliminating the 1383 nm water peak absorption contribution from any capillary component incorporated into a fiber preform or optical assembly.
Technical Specifications — Synthetic Quartz Capillary Tube
| Parameter | Value / Grade |
|---|---|
| Product Type | Synthetic quartz capillary tube / high-UV fused silica capillary |
| Material | Synthetic fused silica, SiO₂ ≥99.9999% (6N grade) |
| Metallic Impurities | <20 ppb total — verified by ICP-MS analysis |
| OH Hydroxyl Content | <1 ppm — ultra-low for fiber and UV optical applications |
| UV Transmittance | High — low UV absorption, suitable for deep-UV and UV laser applications |
| Max. Service Temperature | ~1200°C continuous service |
| Thermal Expansion | 0.55 × 10⁻⁶ /°C — near-zero thermal expansion |
| OD | ≤10 mm |
| Wall Thickness (WT) | ≤1.5 mm |
| Max. Length | ≤2000 mm |
| Material Certificate | Full ICP-MS impurity analysis Certificate of Conformity (CoC), supplied as standard |
Major Metallic Impurity Content & Hydroxyl — ICP-MS Tested
All values in ppm (wt). Total metallic impurity content <20 ppb, verified by ICP-MS (inductively coupled plasma mass spectrometry). Full ICP-MS analysis Certificate of Conformity provided as standard with every order.
| Grade | Li | Na | K | Mg | Ca | Cu | Al | Cr | Fe | Ti | OH (ppm) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Capillary | <0.001 | <0.005 | <0.002 | <0.001 | <0.003 | <0.001 | <0.003 | <0.001 | <0.002 | <0.001 | <1 |
* Capillary tube is a synthetic quartz tube with ultra-low metallic impurity content (<20 ppb total). All impurity testing performed by ICP-MS. Full ICP-MS Certificate of Conformity supplied as standard.
Geometric Specifications & Dimensional Tolerances
OD = outer diameter · WT = wall thickness. Custom OD, WT and length available on request — provide OD × WT × Length (mm) when enquiring.
| Parameter | Capillary Tube |
|---|---|
| OD (mm) | ≤10 |
| WT (mm) | ≤1.5 |
| OD Tolerance (mm) | ±0.20 |
| WT Tolerance (mm) | ±0.20 |
| Out-of-Roundness (mm) | ≤0.08 |
| Wall Eccentricity (mm) | ≤0.08 |
| CSA Relative Difference | ≤3.0% |
| Bow (mm/m) | ≤0.40 |
| Length (mm) | ≤2000 |
* Custom OD, WT and length specifications available on request. Provide OD × WT × Length (mm) when enquiring.
Optical Quality Standard — Bubble Inclusion Count
Maximum allowable bubble count per metre of tube length, by bubble diameter and wall thickness class.
| Bubble Diameter (mm) | Wall Thickness — Max. Allowable Count (no./m) | |||
|---|---|---|---|---|
| ≤3 mm | >3 – ≤10 mm | >10 – ≤25 mm | >25 mm | |
| >0.2 – ≤0.5 | 3 | 7 | 14 | 21 |
| >0.5 – ≤1.0 | 0 | 3 | 6 | 9 |
All bubbles characterised by width; length must not exceed 8 mm. Bubbles ≤0.2 mm not counted. *WT ≤3 mm: open bubbles not permitted. No visible surface defects to naked eye.
Why Synthetic Fused Silica Matters for Capillary UV Performance
Standard borosilicate and natural fused quartz capillaries contain inherent metallic impurities — including iron, aluminium and sodium — at the ppm level. These impurities create absorption centres in the UV and deep-UV spectrum, reducing transmittance and increasing scattering loss. In contrast, the LUMIGLAS® synthetic quartz capillary tube starts from a CVD-derived silica precursor with no natural mineral contamination. Consequently, all metallic impurities stay below 20 ppb total, and the UV transmittance of the tube wall is significantly higher than that of natural fused quartz. For this reason, the synthetic quartz capillary is the standard choice wherever UV transmission through the capillary wall directly affects performance.
What ICP-MS Testing Means for Capillary Purity
ICP-MS (inductively coupled plasma mass spectrometry) is the most sensitive technique for trace metallic impurity analysis in fused silica, with detection limits in the sub-ppb range. For optical fiber and specialty fiber preform applications, metallic impurities at the ppb level can contribute to scattering loss and absorption loss in the finished fiber. Standard wet-chemistry or atomic absorption spectroscopy methods cannot reliably verify compliance at this level. Therefore, by specifying ICP-MS as the verification method and setting a total metallic impurity limit of <20 ppb, the LUMIGLAS® capillary guarantees contamination control with full analytical traceability. In addition, the ICP-MS Certificate of Conformity that Lumistar supplies with every order provides the process qualification documentation that fiber preform manufacturers require.
<20 ppb Total — ICP-MS Verified
All metallic impurities are controlled to below 20 ppb total, verified by ICP-MS analysis — the most sensitive method available for trace metal quantification in fused silica. Full ICP-MS CoC supplied as standard with every shipment.
High UV Transmittance & Low Absorption
Synthetic fused silica base glass delivers high UV transmittance from 160 nm upward, with low absorption at deep-UV wavelengths — making this capillary suitable for UV laser beam delivery, UV spectroscopy flow cells and UV optical fiber applications.
Tight Bore Concentricity
OD tolerance ±0.20 mm, WT tolerance ±0.20 mm, out-of-roundness ≤0.08 mm and wall eccentricity ≤0.08 mm — achieving the precise bore concentricity required for fiber preform assembly and micro-optical component integration.
OH <1 ppm
OH hydroxyl content below 1 ppm eliminates the 1383 nm water peak absorption — critical for any capillary component incorporated into an optical fiber preform or used in near-IR and telecom-band optical assemblies.
Typical Applications
- ▸Optical fiber preform inner bore capillary tubes — MCVD and PCVD process inner bore substrates where precise concentricity and ultra-low metallic contamination are required
- ▸Photonic crystal fiber (PCF) capillary elements — precision-bore capillary tubes for the air hole array structure in hollow-core and solid-core photonic crystal fiber preform stacking
- ▸Polarisation-maintaining fiber stress element capillaries — boron-doped or fluorine-doped capillary tubes incorporated as stress elements in PANDA-type PM fiber preform assemblies
- ▸UV laser beam delivery capillaries — synthetic fused silica capillary for guiding UV and deep-UV laser beams in excimer laser, UV lithography and laser marking systems
- ▸UV spectroscopy and chromatography flow cells — high-UV-transmittance capillary flow cells for HPLC UV detection, capillary electrophoresis (CE) and other analytical instruments requiring UV-transparent fused silica capillary
- ▸Micro-optical and precision instrument components — wherever a precision-bore, ultra-pure fused silica capillary tube is required for optical, photonic or analytical instrumentation
Technical Document & Download
📄 Technical Datasheet — Synthetic Quartz Capillary Tube
Full ICP-MS impurity data, dimensional tolerance table, bubble inclusion standard and ordering specification.
Frequently Asked Questions
Request a Quote — LUMIGLAS® Synthetic Quartz Capillary Tube
Specify: OD × WT × Length (mm) · Quantity · ICP-MS CoC required · Custom dimensions welcome
