Keysight Technologies 81618A User Manual

Also see for 81618A: User guide

Contents

Keysight Technologies 81618A User Manual Manual pdf 48 page image

48 Keysight 81618A/9A and Keysight 81620B/3B/4B/6B/8B Optical Heads User’s Guide4 Performance TestsPerformance TestsThe performance tests given in this se ction includes the Accuracy Test, theLinearity Test, the Return Loss Test (for the 81623B/26B) and the NoiseTest. The performance tests for the Keysight 81624B/6B also include – asoptional tests – the Relative Polarization Uncertainty and the RelativeInterference Uncertainty Test. Perform each step in the order given, usingthe corresponding test equipment.The optical cables from the laser source to the 8156A Attenuator and fromthere to the power meter must be fixed to the table to ensure minimumcable movement during the tests.For 81628B onlyThe performance test for the 81628B High Power Head does not differfrom the test procedure for an optical head without an integrating sphere,except for the linearity test. The integrating sphere of the 81628B has tobe disconnected for testing the linearity of the head alone. A specialadapter and a disconnecting tool are necessary for disconnection. Thesetools are included in the Performance Test Kit (order P/N 81628-68705).If the integrating sphere is disconnected the performance of the 81628Bhas to be verified. If performing a performance test on the 81628B thatincludes the linearity test, it is necessary to start the procedure with thelinearity test and then perform the accuracy and noise tests afterwards.The non-linearity of the 81628B is not normally tested up to the specifiedpower level of +38 dBm. The linearity test only verifies the linearity of thehead without the integrating sphere up to 10 dBm (equivalent to 40 dBmwith the integrating sphere). The attenuation of the integrating sphere istypically 31 ± 1 dB, hence the maximum input power for the photodiode isin the range 6 - 8 dBm and so the test described below covers this inputpower range of the photodiode. The contribution of the sphere to thenon-linearity is caused by the heating of the sphere due to applied power >30 dBm. These linearity characteristics are determined by sample testingof the 81628B in OCMD’s metrology lab.NOTE Make sure that all optical connections are dry and clean. DO NOT USEINDEX MATCHING OIL. For cleaning, use the cleaning instructions givenin Cleaning Information on page 87.