Calibrating the D50-SMA

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Thorlabs offers lapping (polishing) sheets to polish a connector after the fiber has been epoxied into the ceramic ferrule. Polishing or Lapping Film is composed of tiny particles glued to a substrate. By moving the connector over the polishing film, excess material is removed and the fiber end is polished. Different grades of polishing film are used in successive polishing cycles. Each polishing cycle uses a finer grit paper.

Our diamond sheets have tiny diamond particles glued to a substrate of polyester with resin. We highly recommend a five step polishing process: the first four steps using diamond sheets in four different grit sizes of 30, 6, 3, and 1 µm, and the fifth using our final polishing sheets. To use, drop distilled water on to the sheet and polish in a figure-eight motion using an appropriate polishing puck (sold below).

Our Final Polishing Sheets (LFCF), which eliminate the need for slurry, are designed to be used as the last step in the fiber polishing process. These sheets are made by coating polyester film with precision-grade silicon dioxide. These sheets produce an excellent surface finish with minimal scratches and offer no binder contamination on the optical fiber during polishing.

We recommend using these sheets over the less expensive aluminum oxide/silicon carbide sheets when polishing ceramic or zirconia ferrules because they do not cause undercutting when polishing the connector like silicon carbide can. Undercutting occurs when the fiber material is removed quicker than the ferrule material creating a dip just above the fiber. When the connector is mated to another connector, instead of obtaining a glass-to-glass interface, the air gap created by the undercutting causes a glass-air-glass interface and excess loss, which is undesirable.

Despite the higher upfront cost per sheet, each area of the sheet can be used up to 20 times instead of once, compared to the aluminum oxide/silicon carbide sheets featured below. This greatly increasing its value. These 6” x 6” sheets should be used with our glass polishing plates and rubber mats (see below).

Note: The diamond and final polishing films are sold in packages of 5.

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Thorlabs offers Aluminum Oxide and Silicon Carbide lapping / polishing sheets to polish a connector after the fiber has been epoxied into the ferrule. Lapping sheets are like sandpaper for optical connectors. Tiny aluminum oxide or silicon carbide particles are glued to a substrate of polyester with resin. Since we highly recommend a four step polishing process when using aluminum oxide or silicon carbide sheets, we offer our sheets in four different grit sizes: 3, 1, and 0.3 µm grits using Aluminum Oxide and 5 µm grit using Silicon Carbide.

Typically, each area of each sheet can only be used once to polish a single connector. Also, care should be taken when polishing your connector as these sheets can cause undercutting especially with ceramic or zirconia ferrules. Undercutting occurs when the fiber material is removed quicker than the ferrule material creating a dip just above the fiber. When the connector is mated to another connector, instead of getting a good glass-to-glass interface, the air gap created by the undercutting causes a glass-air-glass interface and undesirable excess loss.

These 13” x 9” sheets should be used with our glass polishing plates and rubber mats (see below).

Note: Aluminum oxide and silicon carbide sheets are sold in packages of 10.

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In order to hold the fiber connector securely and to maintain the proper angle, a Manual Fiber Polishing Puck is used. The puck makes it easier to hold the connector against the polishing film and ensures an even polish. We offer polishing discs for six different connector types. Please note that discs are specific to the type of connector: they are not interchangeable.

SMA Connector Polishing Disc
This polishing disc will accommodate both SMA type 905 and SMA type 906 connectors. Each disc is factory set to produce the correct ferrule length after polishing is complete. The D50-SMA polishing disc can be recalibrated using our D50-A calibration pin, which is included with the D50-SMA polishing disc. For information on the recalibration procedure, please view the D50-SMA Calibration tab above.

FC/PC and SC/PC Connector Polishing Disc
This polishing disc will accommodate both flat and pre-radiused (PC style) connectors.

FC/APC Connector Polishing Disc
This polishing disc is designed to polish ferrules at 8° while securing the connector key in the proper orientation with respect to the polish angle.

ST/PC or LC/PC Connector Polishing Disc
The polishing disc is designed to allow the ST/PC (D50-ST) or LC/PC (D50-LC) connector to float. This design allows the polishing of both flat and pre-radiused (PC style) connectors.

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D50-F Polishing Puck in Jig with Secured Ferrule

Thorlabs’ bare ferrule polishing pucks provide a convenient and secure platform to evenly polish bare ferrules. Each puck includes a jig that is used to set the depth of the ferrule and a set screw that firmly holds the ferrule in the puck. To use, simply place the puck on the jig, drop the ferrule into place, and tighten down the setscrew with the included 0.050" hex key (see image to the right). The puck will ensure that the ferrule is held perpendicular to the polishing surface while allowing the user to polish by holding the puck instead of the ferrule. During the polishing process, it may be necessary to return the puck to the jig in order to reset the proper depth. This simple yet practical device alleviates concerns of damaging or breaking the fiber while polishing the ferrule.

We offer the D50-F polishing puck for FC/PC and SC/PC ferrules and the D50-L for LC/PC ferrules.

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Polishing Pad on Glass Polishing Plate

Glass Polishing Plate
Polishing of fiber optic connectors requires a flat hard surface. The glass plate is produced from safety glass with all edges and corners rounded. Rubber feet help to ensure the plate will not mar the work surface and keeps the plate from sliding.

Polishing Pad
This rubber polishing pad (50 Durometer) is required when polishing PC style pre-radiused connectors. When used with our glass polishing plate, as shown in the photo to the right, the pad helps to maintain the geometry of the connector tip during polishing.

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Guide to Connectorization and Polishing of Optical Fibers
The FN96A Polishing and Connectorization Guide contains easy-to-follow, step-by-step instructions that show the reader how to properly cleave a fiber, assemble a cable and connector, and polish the connector. A color manual can be purchased below, or it can be downloaded here in PDF format for free.

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Thorlabs' Connectorization Kits contain all of the materials for your connectorization needs (connectors and fiber not included). The CK03 and CK05 kits include an NRS913 Rubber Polishing Pad (50 Durometer) that is used to produce PC (radiused) polishes.

To view the Material Safety Data Sheets (MSDS) associated with the F112 epoxy that is included with these kits, please click on the part number in the list to the right and go to the Documents tab.