OPTICAL SIGNAL ANALYZER (OSA) 2A1A1 (E/O BENCH WITH OSA ONLY)

TM 11-6625-3081-23 1-12. DESCRIPTION OF DAYSIDE TEST BENCH 2A1 (cont) 1-12 c. OPTICAL SIGNAL ANALYZER (OSA) 2A1A1 (E/O BENCH WITH OSA ONLY) (1) The OSA is an electro-optical test chassis that provides an enclosure and test capability for two UUTs, heads out display (HOD), and heads down display/indirect view display (HDD/IVD). Located on front of the dayside test bench, the OSA consists of a housing assembly, plate assembly, and electrical and mechanical assemblies. Drawer slides allow extension away from the cabinet for maintenance. (2) The OSA housing assembly is an aluminum alloy frame that interfaces with the plate assembly. The front panel consists of an air filter (dust arresting electro- magnetic shielding air vent panel), 10 electrical connectors, a fiber optics connec- tor, and a main access door. The door provides access to the OSA bay for installing the UUTs. A main door interlock switch assembly 2A1A1A5 is mounted on the housing assembly and actuates when the door is closed. The door is light tight and provides a dust free bay for the UUTs. Maintaining a light seal prevents damage to the photo- multiplier tube (PMT) by a sudden exposure to light. Light from an 1-250 illuminator is directed through a fiber optics bundle to the fiber optics connector. From there, another fiber optics bundle directs the light into the OSA, for use during testing. Two sliding flush latch assemblies lock/unlock the door. Two bow handles provide carrying leverage. (3) The side panel contains the PMT/PMT housing, PMT door interlock switch assem- bly 2A1A1A11, and electrical connections. These components are located behind the PMT door. The interlock switch is actuated when the door is closed and secured to the housing with two quick-release captive screws. (4) The plate assembly mounts on the rear of the housing assembly and supports the chassis. Items mounted to the plate assembly include the following: Photon emitter assembly 2A1A1A3 Bracket assembly (focus motor) 2A1A1A4 Power supply assembly 2A1A1A6 Photomultiplier/bracket assembly (PMT tube and shutter) 2A1A1A7 Interface assembly 2A1A1A8 Relay assembly 2A1A1A12 Filter and detector assembly 2A1A1A14 Mechanical assemblies (a) The photon emitter assembly 2A1A1A3 (calibration light source test LED) consists of a CCA and cover assembly. The CCA contains a resistor network and light emitting diode (green diffused LED). The LED is the test light source situated behind a mask of hole patterns that provides a monitoring source for the PMT. (b) The mounting bracket assembly 2A1A1A4 (focus motor) focuses on the CRT of the HOD. It consists of a stepper motor assembly (O to 32,000 steps), target wheel sensor assembly, motor adapting plate, adjusting bracket, and a clamping bracket assembly. Two quick-release pins (part of clamping bracket assembly) secure the HOD to the mounting bracket assembly. Change 4 1-37