What are the indicators for determining the grinding quality of fiber optic connectors

Fiber optic cables are considered a high-quality carrier for high-speed data transmission due to their efficient transmission capabilities, and fiber optic connector components play a crucial role in fiber optic communication. The data transmission requires grinding the connector end face to maximize its performance, and the grinding of the connector end face determines its optical wave transmission quality. For the vast majority of glass optical fibers with a cladding diameter greater than 200 microns, end face grinding is a common method to ensure the quality of optical transmission, and the grinding quality is generally judged by the following five indicators.
Echo reflection, currently, the industry standard for echo reflection is<-55dB. Due to signal distortion, the expected high data rate may encounter data bit errors, resulting in a system transmission problem that depends on the speed and clarity of the fiber optic system due to high-level echo reflection. Usually, the connectors we refer to are represented by PC, SPC, UPC, and APC. These English abbreviations describe the end face type of the connector and are related to the design of echo reflection.
Insertion loss refers to the power loss of two connectors during docking. The reasons for high insertion loss include misalignment of fiber optic docking, inadequate connection, and poor grinding quality of connector end faces. At present, the specified value for insertion loss is<0.5db, but the general expected value has become<0.3db.
Vertex offset, "vertex" refers to the highest point of the connector end face. Vertex offset refers to the measured distance between the highest point of the fiber core and the connector after grinding. Excessive vertex offset can result in high insertion loss and high echo reflection.
The curvature radius is an indicator for measuring the curvature of the connector end face. An appropriate diameter plus an acceptable amount of fiber indentation will optimize the crimping of the fiber to the connector. The industrial standard for curvature radius is 10-25mm. This range achieves the maximum performance of the connector.
The amount of fiber indentation/protrusion measures the distance that the fiber is inserted into the connector pin, but a portion of the fiber may also remain outside the pin. These two situations directly depend on the grinding process and can be measured by an interferometer. The usual specified value for fiber optic indentation is greater than 50nm. Fiber optic indentation can affect echo reflection and insertion loss. When the connector is aligned, the pin material around the fiber optic cable will be tightly pressed, maximizing the tight contact of the fiber optic cable with the appropriate amount of indentation/protrusion. There will be air gaps between fibers that are not tightly connected. The air gap can cause unacceptable echo reflection and insertion loss values.