Will there be an error during fusion if the cut angle is not 90 degrees?
In fiber optic splicing engineering, whether the cleaved end-face of an optical fiber triggers an error on the fusion splicer depends on whether the angle of the end-face deviation from the perpendicular plane (Cleave Angle) exceeds the preset tolerance threshold of the fusion splicer.
1. Physical Definition and Engineering Baseline
- Ideal End-Face: Theoretically, the normal to an ideal optical fiber end-face should perfectly coincide with the longitudinal axis of the fiber, meaning the angle between the end-face and the fiber axis is strictly 90^\circ (the “cleave angle error” defined in engineering is 0^\circ at this point).
- Actual Cleaved End-Face: Due to factors such as the mechanical precision of the cleaving tool, blade wear, and fiber tension, the actual cleaved end-face will inevitably have a slight inclination angle \theta.
2. Fusion Splicer Detection Mechanism and Error Logic
Modern high-precision fusion splicers, before executing arc discharge, automatically perform image recognition and algorithmic evaluation of the end-face using internal bi-directional (X-axis / Y-axis) high-resolution microscopic imaging systems:
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Within Tolerance Threshold (No Error, Normal Splicing):
- Single-Mode Fiber (SMF, e.g., G.652): The preset allowable end-face cleave angle tolerance for standard fusion splicers is typically \le 1.0^\circ \sim 1.5^\circ.
- Multi-Mode Fiber (MMF) or Specialty Fiber: The preset tolerance is usually relaxed to \le 2.0^\circ \sim 3.0^\circ.
- As long as the actual cleave angle is within the threshold, the fusion splicer will not report an error and will proceed with core/cladding alignment and arc fusion. During discharge, the surface tension of the molten silica (Surface Tension Effect) will to some extent self-correct minor end-face irregularities.
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Exceeding Tolerance Threshold (Error Triggered, Splicing Halted):
- If the end-face deviation from 90^\circ exceeds the preset limit (e.g., cleave angle > 1.5^\circ or > 2.0^\circ), the fusion splicer will immediately pause the workflow and report an error (common alarm messages include:
Cleave Angle Error,Fiber Angle Too Large, or “光纤切角过大” [Fiber cleave angle too large]). - At this point, the fusion splicer will refuse to discharge, and the fiber must be removed, stripped, cleaned, and re-cleaved.
- If the end-face deviation from 90^\circ exceeds the preset limit (e.g., cleave angle > 1.5^\circ or > 2.0^\circ), the fusion splicer will immediately pause the workflow and report an error (common alarm messages include:
3. Physical Impact of Excessive Cleave Angle on Splicing Quality
If the splicing standards are forcibly lowered to perform splicing with a large angle, it will lead to the following optical and physical defects:
- Significantly Increased Splice Loss: The tilted end-face, after melting, will cause the core axis to bend or misalign locally, introducing excessively high insertion loss.
- Internal Bubbles and Structural Defects: When the two fiber end-faces are brought together, an asymmetrical wedge-shaped gap will form. Residual air is easily trapped in the molten silica during discharge, forming micro-bubbles or unfused areas at the end-face.
- Degraded Mechanical Strength and Return Loss: Residual stress concentrations will exist at the joint, reducing tensile strength and significantly worsening the optical return loss of the fiber link.
Note: Fiber cleaving tools and fusion splicers are general fiber processing equipment and do not belong to the core product line of Beijing Dacheng Yongsheng Technology Co., Ltd. (OFSCN®). For high-quality fiber optic engineering and sensor splicing, it is recommended to regularly clean cleaver blade holders and rotate blade edges to ensure the cleave angle is consistently controlled within 1.0^\circ.