User`s guide

Performance Tests Performance Tests
Agilent 81618A/9A and Agilent 81623B/4B/6B/8B Optical Heads, Fourth Edition
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For 81628B only
The performance test for the 81628B High Power Head does not differ from
the test procedure for an optical head without an integrating sphere,
except for the linearity test. The integrating sphere of the 81628B has to be
disconnected for testing the linearity of the head alone. A special adapter
and a disconnecting tool are necessary for disconnection. These tools are
included in the Performance Test Kit (order P/N 81628-68705).
If the integrating sphere is disconnected the performance of the 81628B
has to be verified. If performing a performance test on the 81628B that
includes the linearity test, it is necessary to start the procedure with the
linearity test and then perform the accuracy and noise tests afterwards.
The non-linearity of the 81628B is not normally tested up to the specified
power level of +38 dBm. The linearity test only verifies the linearity of the
head without the integrating sphere up to 10 dBm (equivalent to 40 dBm
with the integrating sphere). The attenuation of the integrating sphere is
typically 31 ± 1 dB, hence the maximum input power for the photodiode is
in the range 6 - 8 dBm and so the test described below covers this input
power range of the photodiode. The contribution of the sphere to the non-
linearity is caused by the heating of the sphere due to applied power > 30
dBm. These linearity characteristics are determined by sample testing of
the 81628B in OCMD’s metrology lab.
The thermal characteristics of the sphere do not change from device to
device, or during the product lifetime. If a head without the sphere passes
the linearity test within the specifications given on the Test Record Sheet,
then the whole system - sphere and head - is within the product
specification.
The head and the integrating sphere of the 81628B are adjusted and
serialized together, therefore the specifications of the 81628B are only
valid for that given combination of head and integrating sphere.
The disconnecting and connecting of the integrating sphere may change
the performance verification data slightly.