Si Switchable Gain Detector
Chapter 3: Setup
Rev E, July 15, 2017
Page 3
Chapter 3 Setup
The detector can be set up in many different ways using our extensive line of
adapters. However, the detector should always be mounted and secured for best
operation.
1. Unpack the optical head, install a Thorlabs TR-series ½" diameter post
into one of the #8-32 (M4 on -EC version) tapped holes, located on the
bottom and side of the head, and mount into a PH-series post holder.
2. Connect the power supply 3-pin plug into the power receptacle on the
PDA36A(-EC).
3. Plug the power supply into a 50 to 60 Hz, 100 to 120 VAC outlet (220 to
240 VAC for -EC version).
4. Attach a 50
Ω
coax cable (i.e. RG-58U) to the output of the PDA. When
running cable lengths longer than 12" we recommend terminating the
opposite end of the coax with a 50
Ω
resistor (Thorlabs p/n T4119) for
maximum performance. Connect the remaining end to a measurement
device such as an oscilloscope or high speed DAQ card. Caution: Many
high speed oscilloscopes have input impedances of 50
Ω
. In this case,
do not install a 50
Ω
terminator. The combined loads will equal 25
Ω
which could allow ~135 mA of output current. This will damage the
output driver of the PDA36A(-EC).
5. Power the PDA36A(-EC) on using the power switch located on the top
side of the unit.
Caution!
The PDA36A(-EC) was designed to allow maximum accessibility to the
photodetector by having the front surface of the diode flush with the outside
of the PDA housing. When using fiber adapters, make sure that the fiber
ferrule does not crash into the detector. Failure to do so may cause damage
to the diode and or the fiber. An easy way to accomplish this is to install a
SM1RR retaining ring [included with the PDA36A(-EC)] inside the 1" threaded
coupler before installing the fiber adapter
6. Install any desired filters, optics, adapters, or fiber adapters to the input
aperture.
7. During alignment, take appropriate precautions, such as using reduced
radiation power, or other precautions, and use proper eye and/or skin
protection as recommended by the radiation source manufacturer.
8. Apply a light source to the detector. Adjust the gain to the desired
setting.
!
!
