THORLABS PDA10A2 User manual

PDA10A2
Si Amplified Fixed Gain
Detector
User Guide

Si Amplified Fixed Gain Detector
Table of Contents
Chapter 1 Warning Symbol Definitions ...........................................1
Chapter 2 Description........................................................................2
Chapter 3 Setup..................................................................................3
Chapter 4 Operation...........................................................................4
4.1. Theory of Operation......................................................4
4.2. Responsivity .................................................................4
4.3. Dark Current .................................................................4
4.4. Bandwidth and Response ..............................................5
4.5. Terminating Resistance.................................................5
Chapter 5 Troubleshooting...............................................................6
Chapter 6 Specifications...................................................................7
6.1. Response Curve.............................................................9
6.2. Mechanical Drawing ...................................................10
Chapter 7 Certificate of Conformance ...........................................11
Chapter 8 Regulatory.......................................................................12
Chapter 9 Thorlabs Worldwide Contacts.......................................13

Si Amplified Fixed Gain Detector Chapter 1: Warning Symbol Definitions
Rev B, January 3, 2019 Page 1
Chapter 1 Warning Symbol Definitions
Below is a list of warning symbols you may encounter in this manual or on your
device.
Symbol
Description
Direct Current
Alternating Current
Both Direct and Alternating Current
Earth Ground Terminal
Protective Conductor Terminal
Frame or chassis Terminal
Equipotentiality
On (Supply)
Off (Supply)
In Position of a Bi-Stable Push Control
Out Position of a Bi-Stable Push Control
Caution, Risk of Electric Shock
Caution, Hot Surface
Caution, Risk of Danger
Warning, Laser Radiation
Caution: ESD Sensitive Components

Si Amplified Fixed Gain Detector
Page 2 TTN134700-D02
Chapter 2 Description
The PDA10A2 is an amplified, silicon detector designed for detection of light
signals ranging from 200 to 1100 nm. A buffered output drives 50 Ωload
impedances up to 5 V. The PDA10A2 housing includes a removable threaded
coupler (SM1T1) and retainer ring (SM1RR) that is compatible with any number of
Thorlabs 1” threaded accessories. This allows convenient mounting of external
optics, light filters, apertures, as well as providing an easy mounting mechanism
using Thorlabs’cage assembly accessories.
ESD Caution
The components inside this instrument are ESD sensitive. Take all
appropriate precautions to discharge personnel and equipment before
making any electrical connections to the unit.
Caution!
Long-term exposure to high-energy UV light may degrade the performance
and specifications of this Si detector.

Si Amplified Fixed Gain Detector Chapter 3: Setup
Rev B, January 3, 2019 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 either an imperial or metric optical post
into one of the mounting holes located on the bottom and side of the
sensor, and mount using a post holder. Note that these detectors
feature tapped holes that accept both 8-32 and M4 threads, so using
either imperial or metric TR posts is possible.
2. Connect the power supply 3-pin plug into the power receptacle on the
PDA10A2.
3. Plug the power supply into a 50 to 60Hz, 100 V / 120 V / 230 V power
outlet.
4. Attach a 50 Ωcoax 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 Ωresistor (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 Ωterminator. The combined loads will equal 25 Ωwhich
could allow ~135 mA of output current. This will damage the output driver
of the PDA10A2.
5. Power the PDA10A2 on using the power switch located on the top side
of the unit.
Caution!
The PDA10A2 was designed to allow maximum accessibility to the
photodetector by having the active area 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.
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.

Si Amplified Fixed Gain Detector
Page 4 TTN134700-D02
Chapter 4 Operation
4.1. Theory of Operation
Thorlabs PDA series are ideal for measuring both pulsed and CW light sources.
The PDA10A2 includes a reverse-biased PIN photo diode, mated to a fixed gain
transimpedance amplifier, and packaged in a rugged housing.
4.2. Responsivity
The responsivity of a photodiode can be defined as a ratio of generated
photocurrent (IPD) to the incident light power (P) at a given wavelength:
󰇛󰇜

4.3. Dark Current
Dark current is leakage current which flows when a bias voltage is applied to a
photodiode. The PDA with Transimpedance Amplifier does control the dark current
flowing out. Looking at the figure above, it can be noted that Point B is held at
ground and the amplifier will try to hold point A to “Virtual Ground”. This minimizes
the effects of dark current present in the system.
The dark current present is also affected by the photodiode material and the size
of the active area. Silicon devices generally produce low dark current compared
to germanium devices which have high dark currents. The table below lists
several photodiode materials and their relative dark currents, speeds, sensitivity,
and costs. Please note that sensitivity values in the table are typical values;
Thorlabs offers photodetectors with sensitivity ranges that vary from those shown
below.

Si Amplified Fixed Gain Detector Chapter 4: Operation
Rev B, January 3, 2019 Page 5
Material
Dark Current
Speed
Sensitivity1
Cost
Silicon (Si)
Low
High
400 - 1000 nm
Low
Germanium (Ge)
High
Low
900 - 1600 nm
Low
Gallium Phosphide (GaP)
Low
High
150 - 550 nm
Med
Indium Gallium Arsenide
(InGaAs)
Low
High
800 - 1800 nm
Med
Extended Range: Indium
Gallium Arsenide (InGaAs)
High
High
1200 - 2600 nm
High
4.4. Bandwidth and Response
For the PDA detectors, the gain of the detector is dependent on the feedback
element (Rf). The bandwidth of the detector can be calculated using the following:
󰇛󰇜

Where GBP is the amplifier gain bandwidth product and CDis the sum of the
photodiode junction capacitance and the amplifier capacitance.
4.5. Terminating Resistance
The maximum output of the PDA10A2 is 10 volts for high impedance loads (i.e.
RLoad > 5 kΩ) and 5 V for 50 Ω loads. Adjust the gain so that the measured signal
level out of the PDA10A2 is below 10 V (5 V with a 50 Ω load) to avoid saturation.
For low terminating resistors, <5 kΩ or 1% error, an additional factor needs to be
considered. The output of the PDA includes a 50 Ω series resistor (Rs). The output
load creates a voltage divider with the 50 Ω series resistor as follows:
 

 
󰇛󰇜󰇛󰇜
Note that we already include the scale factor in our specification for the gain at
50 Ω. Refer to the table in Chapter 6 for additional performance specifications.
1
Approximate values; actual wavelength values will vary.

Si Amplified Fixed Gain Detector
Page 6 TTN134700-D02
Chapter 5 Troubleshooting
Problem
Suggested Solutions
There is no signal response.
Verify that the power is switched on and all
connections are secure.
Verify the proper terminating resistor is installed if
using a Voltage measurement device.
Verify that the optical signal wavelength is within
the specified wavelength range.
Verify that the optical signal is illuminating the
detector active area.
Output Voltage will not increase.
Detector Output is skewed.
Check to make sure the detector is not saturated.
Refer to the Output Voltage spec. in the
Specifications table.
Install a 1" Lens Tube (SM1L10) to the thread
coulpler (SM1T1) to baffle any external light
sources to see if this improves the response.

Si Amplified Fixed Gain Detector Chapter 6: Specifications
Rev B, January 3, 2019 Page 7
Chapter 6 Specifications
All performance specifications are typical, performed at 25 °C ambient
temperature, and assume a 50 Ω load, unless stated otherwise.
2
The PDA10A2 has a 50 Ω series terminator resistor (i.e. in series with amplifier output). This
forms a voltage divider with any load impedance (e.g. 50 Ω load divides signal in half).
3
When long-term UV light is applied, the product specifications may degrade. For example, the
product’s UV response may decrease and the dark current may increase. The degree to which
the specifications may degrade is based upon factors such as the irradiation level, intensity, and
usage time.
Electrical Specifications2
Detector
-
Si
Active Area
-
Ø1 mm (0.8 mm2)
Wavelength Range3
λ
200 to 1100 nm
Peak Wavelength
λp
730 nm (Typ)
Peak Response
( λ p)
0.44 A/W (Typ)
Small Signal Bandwidth
-
150 MHz
NEP (λp)
W/√Hz
2.92 x 10-11
Noise (RMS)
-
1.5 mVrms
Max Ouput Current
IOUT
100 mA
Dark Offset
-
±10 mV
Load Impedance
-
50 Ωto Hi-Z
Transimpedance Gain
-
5 x 103V/A (50 Ω)
1 x 104V/A (Hi-Z)
Output Voltage
VOUT
0 to 5 V (50 Ω)
0 to 10 V (Hi-Z)

Si Amplified Fixed Gain Detector
Page 8 TTN134700-D02
4
Measured from the active area to the start of the threads on the housing body. The detector
active area surface is flush with the front of the housing body.
5
Although the power supply is rated for 6 W, the detector’s actual usage is <5 W over the full
operating range.
General
On/Off Switch
Slide
Output
BNC (DC Coupled)
Package Size
2.79" x 1.96" x 0.89"
(70.9 mm x 49.8 mm x 22.5 mm)
PD Surface Depth4
0.09" (2.2 mm)
Weight, Detector Only
0.10 kg
Accessories
SM1T1 Coupler
SM1RR Retainer Ring
Operating Temp
10 to 50 °C
Storage Temp
-25 to 70 °C
AC Power Supply
AC - DC Converter
Input Power5
6 W
100 V / 120 V / 230 V, 50 - 60 Hz