Instrument positioning and core applications
AQ7420 is a high-resolution reflectometer based on the principle of Time Domain Optical Coherence Tomography (TD-OCT) with built-in Michelson interferometer. Its core function is to measure three key parameters of optical devices through USB connection with the control PC
Optical Return Loss (RL): measures the return loss of fiber optic connectors, internal scratches, and device connection points, locates the position (with a maximum accuracy of 1 μ m) and intensity of reflection points.
Burnout Detection: Scan the distribution of return loss throughout the entire measurement range to identify abnormal reflection peaks such as fiber breakage and component defects.
Optical Insertion Loss (IL): measures the power attenuation of an optical signal passing through a Device Under Test (DUT) to evaluate the transmission performance of the device.
The instrument needs to be used in conjunction with a dedicated PC application, supporting local operation and TCP/IP remote control. The measurement results can be automatically graded, saved, and printed to meet the requirements of automated testing.

PC application installation and environmental requirements
1. Hardware and system requirements
Before installation, it is necessary to confirm that the control PC meets the following conditions, otherwise it may cause abnormal software operation or communication failure:
Project Requirements Explanation
The operating systems Windows 10 (32/64 bit) and Windows 11 do not support Windows XP/Vista/7/8 and tablet mode
Hardware configuration with at least 10MB of free hard disk space, USB interface free space for software installation and data storage, USB for instrument communication
Display resolution of 1024 × 768 pixels and above, 256 colors and above to ensure complete display of the operation interface, clear waveform diagram
The driver relies on NI-VISA 16.0 and above versions for communication between instruments and PCs, requiring VISA drivers. If not installed, it needs to be installed from the product CD first
2. Installation and uninstallation process
(1) Software installation steps
Preparation: Close the installed AQ7420 series software (if any) and log in to Windows with administrator privileges.
Start installation: Insert the product CD and run the path in English Application ARB-EDIT Setup. EXE (or enter the path through "Start Menu ->Run").
Driver installation: After completing the PC application installation as prompted, the FTDI CDM driver installation window will automatically pop up. Click "Extract → Next → I agree → Finish" in sequence to complete the driver deployment.
Start verification: After installation is complete, add the "AQ7420Series-OLCR" program under "Start Menu → YOKOGAWA", generate a shortcut icon on the desktop, double-click to start and enter the main interface.
(2) Uninstalling process (taking Windows 11 as an example)
Open "Control Panel ->Apps ->Installed Apps" and find "AQ7420Series'OLCR".
Click on the icon on the right side of the program, select "Uninstall", confirm and complete the uninstallation; If there are any remaining installation folders, they can be manually deleted (self built data needs to be backed up in advance).
(3) Connection exception handling
If the software prompts "Device Error" when starting, check:
Is the USB cable securely connected to the AQ7420 and PC.
Whether the VISA driver is installed properly (can be verified through NI MAX tool).
Whether the instrument power is turned on and whether the warm up is completed (it is recommended to perform reference measurements after preheating for 1 hour).
If you only want to view data without connecting the instrument, you can click "Viewer Mode" to enter the view mode.

Core functions and operating procedures
1. Preparation before measurement
(1) Instrument preheating and reference measurement
Preheating requirement: After starting up, the "Repeat Mode" should be turned on to run for 1 hour for preheating, to avoid temperature drift affecting measurement accuracy; After preheating, the reference measurement calibration system needs to be executed.
Reference measurement type:
Detection REF: The reference measurement for RL and burn detection requires the use of a dedicated main cable (Master Cord), with the open end of the main cable as the measurement starting point (0mm), to record the reference reflection intensity.
IL REF: Reference measurement of insertion loss, connect the main cable directly to the optical input port of AQ740023 sensor head, and record the reference optical power.
All REF: Simultaneously execute Detection REF and IL REF, suitable for scenarios where RL/burn detection and IL need to be measured simultaneously.
(2) Key hardware connections
When measuring different parameters, cables need to be connected according to specifications. The core components include the main cable (standard accessories, can be purchased separately), distance adjustment cable, relay cable, FC/APC adapter, and AQ740023 sensor head. The example connections are as follows:
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