The CertiFiber Pro accepts APC connectors in the?INPUT port ONLY. The APC connector can be attached to the INPUT port because the INPUT port is a non-contact mating. This design feature allows you to set a 1 jumper reference for SC, ST, FC, SC/APC and LC/APC fiber testing.

該福祿克FLUKE?CertiFiber PRO(CFP-100-Q,CFP-100-M,CFP-100-S)光纖測試儀的APC端口，只使用于輸入端口。APC端口能夠適用于輸入端口，因為輸入端口是非接觸式連接。此設計功能允許您設置光纖測試參考為1個跳接對于SC，ST，FC，SC /APC和LC /?APC

The?OUTPUT port uses a UPC connector. This makes a physical contact with the test reference cord. As a result, you cannot insert SC/APC connectors in the OUTPUT port of the tester. No damage will occur; you will simply get a warning from the tester about the received power being too low.

 

APC – Angled Physical Contact
These connectors are color coded green and are found in single mode fiber applications. The end face is slanted 8 degrees. The slight angle reduces back reflections in the core because the reflections are absorbed into the cladding. With CertiFiber Pro, you will need two hybrid UPC to APC cords and two APC to APC cords. Details on the methodology can be found in the two links below:

• Certifying LC/APC links with the CertiFiber Pro
• Certifying SC/APC links with the CertiFiber Pro

 

UPC – Ultra Physical Contact
These connectors are color coded blue for single mode and beige for multimode. The end face of the fiber has an apex so the core makes direct contact to the other core in a mated connection. A PC (Physical Contact) connector has a flat end face increasing the likelihood that an air gap will be present because the cladding can touch before the core does due to its less rounded end face geometry. That air gap with result in an increase in reflectance – something fiber systems do not want to see.

拓展閱讀：

PC指的是緊密接觸（physical contact)，同樣是緊密接觸，根據回波損耗的不同，連接器分為PC, SPC，UPC和APC。SPC指的是super physical contact, UPC指的是ultra physical contact。PC, SPC和UPC工業標準規定的回波損耗分別為-35dB, -40dB和-50dB (回波損耗是指有多少比例的光又被連接器的端面反射，回波損耗越小越好，當然你也可以說回波損耗的值越大越好，不考慮前面那個負號）。不同的連接器原則上不能混接，但PC, SPC和UPC的光纖端面都是平面的，差別在磨的質量，所以，PC,SPC和UPC的混連還不至于對連接器形成永久性的物理損傷。
APC則完全不同，它的端面被磨成一個8度角，就是減少反射，其工業標準的回波損耗為-60dB。APC連接器只能與APC相連接。由于APC的結構與PC完全不同，如果用法蘭盤將這兩種連接器連接，就會損壞連接器的光纖端面。連接APC到PC的辦法：通過PC到APC轉換的光纖跳線來實現。另外要說明的是APC連接器通常是綠色的（而黃色的光纖則只是單模光纖），而且人眼就能看到光纖端面的傾斜。
因此，為了避免實驗過程中連接器使用的混亂（避免毀壞光譜儀等輸入端口），今后我們在購買激光器，跳線等時，應統一要求廠家給配APC連接器。
FC/PC FC/UPC FC/APC能夠混合連接，信號衰減不會很大，按照國標插損應該是小于0.5dB。應用主要取決于適配器的類型，一般通信ODF架用FC多，設備光口用SC多，ST在局域網和廣電較多。