THORLABS PDA8A2 User manual

Silicon Amplified Detector
PDA8A2
Operation Manual
2022

Version:
Date: 1.1 11-Aug-2022
Copyright © 2022 Thorlabs GmbH

Foreword
Contents
1 General Information 1
11.1 Ordering Codes and Accessories
2 Getting Started 2
22.1 Parts List
22.2 Preparation
3 Operating Instruction 3
33.1 Operating Elements
33.2 Mounting
43.3 Operation
43.4 Operating Principle
53.4.1 Optical Input
53.4.2 Electrical Output
4 Maintenance and Service 6
5 Appendix 7
75.1 Technical Data
85.2 Typical Responsivity and Frequency Response
95.3 Drawings
105.4 Safety
115.5 Certifications and Compliances
125.6 Manufacturer Address
125.7 Return of Devices
125.8 Warranty
125.9 Copyright and Exclusion of Reliability
135.10Thorlabs Worldwide Contacts and WEEE policy

© 2022 Thorlabs GmbH
We aim to develop and produce the best solutions for your
applications in the field of optical measurement techniques. To help
us to live up to your expectations and constantly improve our
products, we need your ideas and suggestions. We and our
international partners are looking forward to hearing from you.
Thorlabs GmbH
Warning
Sections marked by this symbol explain dangers that might result in
personal injury or death. Always read the associated information
carefully before performing the indicated procedure.
Please read this advice carefully!
This manual also contains "NOTES" and "HINTS" written in this form.
Attention
Paragraphs preceded by this symbol explain hazards that could
damage the instrument and the connected equipment or may cause
loss of data.
Note

© 2022 Thorlabs GmbH
1 General Information
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1 General Information
The PDA8A2 is a wideband, fixed-gain-amplified silicon detector designed for the detection of
light signals from DC to 50 MHz. A buffered output drives up to 1.8 V into 50 Ω input loads. The
PDA8A2 is sensitive to light within the wavelength range of 320 nm to 1000 nm. The ultra-low
noise design includes an active low-pass filter to prevent aliasing effects and to suppress out of
band noise effectively.
The PDA8A2 detector housing can be integrated in optical setups using convenient 8-32 and
M4 combi-thread mounting holes that are compatible with both imperial and metric threading.
Please see the chapter Mounting for details.
The housing accommodates Thorlabs' SM05 (0.535"-40) and SM1 (1.025"-40) threaded adap-
ters and accessories. This allows convenient mounting of external optics, light filters, and aper-
tures. The product includes a SM1T1 SM1 Coupler Body which adapts the external thread to
an internal thread and holds the SM1RR Retaining Ring and a reusable protective plastic cover
cap. For accessories, please visit our website or contact Thorlabs .
A ±12 VDC power supply is included with each amplified photodetector. The appropriate input
voltage (100 VAC, 120 VAC, 230 VAC) can be selected with a switch on thepower supply .
Attention
Please find all safety information and warnings concerning this product in the chapter Safety
in the Appendix.
1.1 Ordering Codes and Accessories
PDA8A2: Silicon Amplified Photodetector, 320 - 1000 nm, Bandwidth Range DC-50 MHz, Ac-
tive Area Ø0.8 mm (0.5 mm²), Combi-Thread Mounting Holes Compatible with 8-32
and M4 Threads
Included Accessories
·LDS12B Power Supply (±12V, 0.2A), 100 VAC, 120 VAC or 230 VAC Line Voltage
·Plastic Cover Cap (Item # SM1EC2B) on an included SM1T1-SM1 Coupler with a
SM1RR-SM1 Retaining Ring.
Optional Accessories
·PDA-C-72 DC power supply cable to PDA8A2: This cable has a connector on one end
and open wires at the other. The pin-out of the PDA8A2 DC power jack is shown in the
appendix .
Please visit our homepage http://www.thorlabs.com for various accessories like fiber adapters,
posts and post holders, data sheets and further information.
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© 2022 Thorlabs GmbH2
PDA8A2
2 Getting Started
2.1 Parts List
Please inspect the shipping container for damage. Please do not cut through the cardboard.
You might need the box for storage or for returns.
If the shipping container seems to be damaged, keep it until you have inspected the contents
and you have inspected the PDA8A2 mechanically and electrically.
Verify that you have received the following items within the package:
1. PDA8A2 Amplified Photodetector
2. Plastic Cover Cap (Item # SM1EC2B) on SM1T1-SM1 Coupler with an SM1RR-SM1
Retaining Ring
3. LDS12B Power Supply (±12V, 0.2A), 100 VAC, 120 VAC or 230 VAC Line Voltage
4. Quick Reference
2.2 Preparation
Carefully unpack the unit and accessories. If any damage is noticed, do not use the unit.
Contact Thorlabs and have us replace the defective unit.
Note
Prior to operation, please check if the indicated line voltage range on the power supply matches
with your local mains voltage! Adjust the power supply accordingly to 100 VAC, 120 VAC or
230 VAC.
Note
If you prefer to use your own power supply, please ask Thorlabs for an appropriate power
connector cable.
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© 2022 Thorlabs GmbH
3 Operating Instruction
3
3 Operating Instruction
3.1 Operating Elements
The PDA8A2 comes with a SM1T1 SM1 coupler which holds a SM1RR retaining ring and a
protective plastic cover cap.
3.2 Mounting
Prior to mounting the PDA8A2, please follow the instructions given in the chapter prepara-
tion .
Housing
The PDA8A2 is housed in a rugged, shielded, 70.9 mm x 49.9 mm x 22.5 mm aluminum en-
closure. The electrical connectors and the ON/OFF slider are located on the side walls of the
housing for easy access and to minimize the thickness of the PDA8A2 so it can fit into tight
spaces.
Mounting PDA8A2 on an optical table
Mount the PDA8A2 on an optical post by using either of the two tapped mounting holes on the
side and bottom. The combi-thread tapped holes accept both 8-32 and M4 threads, such that
using either imperial or metric TR posts is possible.
Mounting external optics
The PDA8A2 housing allows to mount external optics, filters, apertures or fiber adapters.
The PDA8A2 comes with an SM1T1 SM1 coupler that adapts the external thread to an SM1
internal thread. A retaining ring in the coupler holds the protective cover cap. Please unscrew
the coupler if needed.
The PDA8A2 housing accommodates Thorlabs’ SM05-threaded (0.535"-40) series and SM1-
threaded (1.035"-40) series adapters that are compatible with any number of Thorlabs 1" and
½" threaded accessories. This also allows convenient mounting of lens tubes or cage systems.
For accessories, please visit our website or contact Thorlabs .
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© 2022 Thorlabs GmbH4
PDA8A2
3.3 Operation
Attention
Ensure that the correct mains voltage is selected on the power supply prior to connecting
the power supply to the mains power. Wrong settings for the mains voltage may damage the
power supply. The ±12 V, 250 mA power supply is included, no high voltage power supply is
required for operation.
Electrical Setup
·Mount the detector using the combi-thread mounting holes on the side and bottom of
the device.
·Connect the power supply 3-pin plug into the mating receptacle on the PDA8A2.
·Plug the power supply into an outlet.
·Switch on the power supply
·Attach a 50 Wcoaxial cable (i.e. RG-58U) to the output of the PDA8A2. When running
cable lengths longer than 12", we recommend terminating the opposite end of the coax
with a 50 Wresistor (Thorlabs p/n T4119) for maximum performance.
·Connect the remaining end to a measurement device.
·Move the power slider to I. The green LED on the PDA8A2 indicates the correct power
supply.
Optical Setup
·Remove the plastic cover cap that protects the optical input.
·Mount external optics if needed.
·Align the light source with the optical input. The max Vout is 3.6 V for high impedance loads
(1.8 V for 50 Ω loads). To avoid electrical saturation, keep the output voltage below the
maximum listed in the Technical Data . External neutral density filters or attenuators are
recommended to reduce the input light level in critical cases.
·For maximum linearity performance when measuring focused beams, fiber outputs, or
small diameter beams, do not exceed a maximum intensity of 10 mW/cm2.
Turning off the PDA8A2
Move the power slider to O after finishing the measurements.
3.4 Operating Principle
In principle, the photodiode generates a current in response to the optical input. The TIA then
converts the current to a voltage and amplifies the signal, reaching a frequency response from
true DC to the cutoff frequency. The fixed gain amplifies the signal to 1.8 V at 50 Ω.
The output is passed through a 50 Ω series resistor before reaching the output connector. The
user can apply either a 50 Ω or high-impedance external load depending on the situation.
The PDA8A2 is powered by an external power supply (±12 V, 200 mA) with switchable 100 V,
120 V or 230 V line voltage. The power supply is connected to the PDA8A2 via a 250 mA,
LUMBERG RSMV3 connector.
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© 2022 Thorlabs GmbH
3 Operating Instruction
5
3.4.1 Optical Input
For maximum linearity performance when measuring focused beams, fiber outputs, or small
diameter beams, do not exceed a maximum intensity of 10 mW/cm2.
Note
For optical alignment, use an optical input power below the saturation power while observing
the output voltage on a low-frequency measurement device such as a digital voltmeter.
Use external neutral density filters to reduce the input light level in order to stay below the
maximum output voltage.
The PDA8A2 housing features internal SM05 and external SM1 threads for convenient moun-
ting of lens tubes or cage systems.
3.4.2 Electrical Output
Thorlabs PDA8A2 photodetectors deliver an OUTPUT voltage that is a function of incident light
power Popt, the detector's responsivity Â(l) at a given wavelength, and the transimpedance
gain G:
The detector's responsivity Â(l) for a given wavelength can be read from the spectral
responsivity curve (see Appendix ).
The maximum output of the PDA8A2 is 3.6 V for high-impedance loads and 1.8 V for 50 W
loads. The output signal should be below the maximum output voltage to avoid saturation.
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© 2022 Thorlabs GmbH6
PDA8A2
4 Maintenance and Service
Protect the PDA8A2 from adverse weather conditions. The PDA8A2 is not water resistant. The
unit does not require regular maintenance by the user. There are no serviceable parts in the
PDA8A2 optical head or power supply. The housing may be cleaned by wiping with a soft,
damp cloth. Do not remove covers!
If you suspect a problem with your PDA8A2, please read the section Safety and contact
Thorlabs tech support and an engineer will be happy to assist you.
Attention
The window of the detector should only be cleaned using optical grade wipes.
To avoid damage to the instrument, do not expose it to spray, liquids, or solvents!
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