THORLABS PDA10JT User manual

PDA10JT(-EC) Amplified
MCT Detector
User Guide

Amplified MCT Detector
Table of Contents
Chapter 1 Warning Symbol Definitions ...........................................1
Chapter 2 Safety.................................................................................2
Chapter 3 Description........................................................................3
Chapter 4 Setup..................................................................................4
Chapter 5 Operation...........................................................................6
5.1. Output........................................................................... 6
5.2. Gain Adjustment............................................................ 6
5.3. Bandwidth Filter Adjustment ......................................... 7
5.4. Thermoelectric Cooler.................................................... 7
5.5. Light-to-Voltage Conversion .......................................... 7
Chapter 6 Maintenance......................................................................8
Chapter 7 Specifications...................................................................9
7.1. General.......................................................................... 9
7.2. Detectivity ................................................................... 10
7.3. Filter Bandwidth .......................................................... 11
7.4. Noise Comparison........................................................ 12
7.5. Wavelength Sensitivity ................................................ 13
Chapter 8 Mechanical Drawings.....................................................14
Chapter 9 Regulatory.......................................................................15
Chapter 10 Thorlabs Worldwide Contacts.......................................16

Amplified MCT Detector Chapter 1: Warning Symbol Definitions
Rev G, March 11, 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: Spinning Blades May Cause Harm

Amplified MCT Detector Chapter 2: Safety
Page 2 21417-D02
Chapter 2 Safety
CAUTION
Mount the unit in a position that does not block airflow to the fan and heat sink!
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
PDA10JT.
CAUTION
The PDA10JT 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. Installing an SM1RR retaining ring (included) inside the
2" threaded coupler before installing the fiber adapter will prevent damage.

Amplified MCT Detector Chapter 3: Description
Rev G, March 11, 2019 Page 3
Chapter 3 Description
The PDA10JT is an amplified, TEC-cooled, switchable-gain, switchable-
bandwidth, HgCdTe photoconductive detector. The detector is AC coupled and
requires a chopped or pulsed input detection of light signals over a wavelength
range from 2.0 to 5.4 µm. Two eight-position rotary switches allow the user to vary
the gain in 6 dB steps and select low pass filter bandwidth settings from 1.25 to
160 kHz. A buffered output drives 50Ωload impedances up to 5 volt. A constant
2.5 mA bias current is provided to the detector via a Howland current pump for
improved stability and low noise operation.
The detector is mounted on a thermoelectric cooler and factory set to cool the
detector to -30 °C with a thermistor providing feedback to maintain a constant
temperature. This cooling provides higher detectivity (D*), which results in a lower
offset at the output and allows higher gains. It also reduces thermally generated
noise. The housing is used as a heat sink and includes a fan to increase the cooling
capacity. It is important to note that the cooling fan will keep the heat sink at room
temperature. Without it, the heat sink will heat up causing a higher temperature
drop between the detector element and the heat sink, resulting in larger TEC
currents. Without the fan, the TEC current will operate at its limit (~820 mA) and
the detector element will no longer be temperature stabilized. Offsets will increase
and fluctuate, and output noise will increase. For best results do not block, limit
airflow, or stop the cooling fan.
The detector housing has a threaded mounting aperture around the diode, which
is compatible with any SM1-threaded accessory. The devices ships with an
SM1RR Retaining Ring allowing convenient mounting of external optics, light
filters, apertures, etc. The SM1-threaded mount can be easily integrated into our
cage and lens tube systems.
The PDA10JT has two 8-32 (M4) tapped holes for mounting the detector on a
Ø1/2" optical post in one of two perpendicular directions. The detector includes a
100 - 240 V, 50 - 60 Hz power supply.

Amplified MCT Detector Chapter 4: Setup
Page 4 21417-D02
Chapter 4 Setup
CAUTION
Mount the unit in a position that does not block airflow to the fan and heat sink!
Figure 1 Electrical Connections
1. Unpack the detector head.
2. (Optional) Install a Thorlabs TR-series Ø1/2" diameter post (not
included) 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 (not included).
3. Connect the power supply 4-pin plug into the power receptacle on
the PDA10JT.
4. Plug the power supply into a 50 - 60 Hz, 100 - 240 VAC outlet.
5. 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 T4119 BCN in-line terminator) 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
PDA10JT.
Output Connector for
BNC Connector and
50 ΩCoax
Power Indicator
LED
Power Supply
Connection

Amplified MCT Detector Chapter 4: Setup
Rev G, March 11, 2019 Page 5
6. Turn on the PDA10JT using the power switch located on the top side
of the detector.
7. Install any desired filters, optics, adapters, or fiber adapters to the
input aperture.
CAUTION
The PDA10JT 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. Installing an SM1RR retaining ring (included) inside the
2" threaded coupler before installing the fiber adapter will prevent damage.
8. Apply a light source to the detector. Adjust the gain to the desired
setting. Note: Allow a minute for the TEC controller to stabilize the
temperature. For best results, allow the unit to warm up for about 30
minutes.

Amplified MCT Detector Chapter 5: Operation
Page 6 21417-D02
Chapter 5 Operation
This devices is a photoconductive detector and requires a chopped or pulsed input
over a wavelength range from 2.0 to 5.4 µm. The AC-coupled amplifier circuit is
designed to minimize noise.
Figure 2 Gain Control, LPF Control, and Power Selector
5.1. Output
The maximum output of the PDA10JT is 10 V for high impedance loads
(i.e. RLOAD > 5 kΩ) and 5 V for 50 Ωloads. Adjust the gain so that the measured
signal level out of the PDA10JT is below 10 V (5 V for a 50 Ωload) to avoid
saturation. If necessary, use external neutral density filters to reducethe input light
level. The BNC output signal is buffered with an amplifier capable of driving 50 Ω
loads. A 50 Ωseries resistor is included on the output to impedance match a 50 Ω
coax cable. For best performance, it is recommended operating the PDA10JT with
a 50 Ωterminating load located at the end of the coax cable. While this is not
necessary, it eliminates ringing and distortion due to impedance mismatches.
5.2. Gain Adjustment
The PDA10JT includes a low noise, low offset, high-gain amplifier that allows gain
adjustment over a 40 dB range. The gain is adjusted by rotating the gain control
knob located on the side of the unit. There are 8 gain positions incremented in 6
dB steps. To adjust the gain, follow the steps below.
1. Set the gain switch to 0 dB.
2. Turn on the light source.
3. Adjust the gain setting so the output of the detector is below the
saturation level as indicated by Section 5.1 above.
LPF Selector Switch
Gain Selector
Switch
Power Toggle Switch

Amplified MCT Detector Chapter 5: Operation
Rev G, March 11, 2019 Page 7
5.3. Bandwidth Filter Adjustment
The PDA10JT also includes an adjustable low pass filter with settings from 1.25
kHz to 160 kHz in 8 steps. This filter allows the user to optimize the PDA10JT to
operate at the lowest amount of high frequency optical and electrical noise. The
filter is adjusted by rotating the filter control knob, located on the side of the unit.
To adjust the filter, follow the steps below.
1. Determine the maximum bandwidth required.
2. Set the filter bandwidth switch setting just above the desired
bandwidth.
Note that system signal bandwidth is 80 KHz. The 160 KHz setting is provided to
eliminate high frequency noise introduced above this limit.
5.4. Thermoelectric Cooler
The thermoelectric cooler built into the detector is factory set to cool the detector
to -30 °C with thermistor feedback to stabilize the temperature. The housing is
used as a heat sink and a fan is used to increase the cooling capacity. It is
important to note that the cooling fan will keep the heat sink at room temperature.
Without it, the heat sink will heat up causing a higher temperature drop between
the detector element and the heat sink, resulting in larger TEC currents. Without
the fan, the TEC current will operate at its limit (~820 mA) and the detector element
will no longer be temperature stabilized. Offsets will increase and fluctuate, and
output noise will increase. For best results, do not block, limit airflow, or stop the
cooling fan. This operation is automatic and requires no input or adjustment by the
user.
5.5. Light-to-Voltage Conversion
The Spectral Responsivity, (), can be obtained from Figure 6 on page 13 to
estimate the amount of output voltage to expect. The light-to-voltage conversion
can be estimated by factoring the wavelength-dependent responsivity of the
HgCdTe detector with the gain as shown below:
󰇛󰇜     󰇛󰇜   󰇛󰇜
For low terminating resistors, <5 kΩor 1% error, an additional factor needs to be
included in the above formula. As described above, the output includes a 50 Ω
series resistor (RS). The output load creates a voltage divider with the 50 Ωseries
resistor as follows:
Scale Factor 
󰇛  󰇜
Where, RLOAD is the terminating resistor and RS= 50 Ω. For a standard 50 Ω
terminator, the gain will be scaled by ½ as shown below:
Scale Factor 
󰇛  󰇜 
󰇛󰇜     󰇛󰇜   󰇛󰇜 

Amplified MCT Detector Chapter 6: Maintenance
Page 8 21417-D02
Chapter 6 Maintenance
There are no serviceable parts in the PDA10JT detector or power supply. The
housing may be cleaned by wiping with a soft damp cloth. The window of the
detector should only be cleaned using isopropyl alcohol and optical grade wipes.
If you suspect a problem with your PDA10JT, please contact your local Thorlabs
technical support office and a member of our support team will be happy to assist
you.

Amplified MCT Detector Chapter 7: Specifications
Rev G, March 11, 2019 Page 9
Chapter 7 Specifications
7.1. General
General Specifications1
Optical Specifications
Wavelength Range
2.0 - 5.4 µm
Peak Wavelength (p)
4.8 µm
Peak Response
300 V/W (Typical) @ p
Electrical Specifications
Gain Adjustment Range
40 dB
Gain Steps
8
Gain Settings (dB)
0, 4, 10, 16, 22, 28, 34, 40
Filter Steps
8
Filter Settings (kHz)
1.25, 2.5, 5, 10, 20, 40, 80, 160
Output Voltage
0 - 5 V (50 Ω)
0 - 10 V (Hi-Z)
Output Impedance
50 Ω
Max Output Current
100 mA
Load Impedance
50 Ω - Hi-Z
Offset 2
20 mV (45 mV Max)
Offset Drift (40 dB)
2.7 mV / °C
TEC Temperature
-30 °C
Bias Current
2.5 mA (0 - 40 dB)
Physical Specifications
Detector
MCT (HgCdTe)
Active Area
1 mm2
Surface Depth
0.11" ± 0.02" (2.90 ± 0.40 mm)
Output
BNC
Detector Size
3" x 2.2" x 2.2"
(76.2 mm x 55.9 mm x 55.9 mm)
Weight(Detector / Power Supply)
0.42 lbs / 0.82 lbs (191 g / 372 g)
Power Supply
27 W
Input Power
100 - 240 VAC, 50 - 60 Hz
Storage Temperature
0 to 85 °C
Operating Temperature
0 to 30 °C
1
All measurements performed with a 50 Ωload unless stated otherwise. The PDA10JT 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 Ωload divides signal in half).
2
After the temperature has stabilized on all gain steps. Also note that the worst case offset is on the 40
dB gain step.

Amplified MCT Detector Chapter 7: Specifications
Page 10 21417-D02
Gain (Hi-Z)3
Low Pass Filter
Bandwidth
NEP Values
(@ DC - 160 kHz)4
0 dB
0.8 V/V
160 k
160 kHz
0 dB
1.43 x 10-9 W/√Hz
4 dB
1.6 V/V
80 k
80 kHz
4 dB
7.62 x 10-10 W/√Hz
10 dB
3.2 V/V
40 k
40 kHz
10 dB
4.05 x 10-10 W/√Hz
16 dB
6.3 V/V
20 k
20 kHz
16 dB
2.78 x 10-10 W/√Hz
22 dB
12.6 V/V
10 k
10 kHz
22 dB
2.15 x 10-10 W/√Hz
28 dB
25.2 V/V
5 k
5 kHz
28 dB
2.10 x 10-10 W/√Hz
34 dB
50.1 V/V
2.5 k
2.5 kHz
34 dB
1.97 x 10-10 W/√Hz
40 dB
100 V/V
1.25 k
1.25 kHz
40 dB
1.84 x 10-10 W/√Hz
7.2. Detectivity
Figure 3 PDA10JT Detectivity (D*)
3
Gain with a 50 Ωload is one-half the hi-Z gain.
4
NEP values measured using a 50 Ω load and a low-pass filter setting of 160 kHz; calculated at the
detector’s peak responsivity wavelength.

Amplified MCT Detector Chapter 7: Specifications
Rev G, March 11, 2019 Page 11
Detectivity (D*) is defined as is defined as:
  

Where Ais the area of the photosensitive region of the detector, Δf is the effective
noise bandwidth, and NEP is the noise equivalent power.
7.3. Filter Bandwidth
Figure 4 PDA Filter Bandwidth (50 ΩLoad)

Amplified MCT Detector Chapter 7: Specifications
Page 12 21417-D02
7.4. Noise Comparison
Figure 5 Noise Comparison at Min and Max Gain and Filter Settings

Amplified MCT Detector Chapter 7: Specifications
Rev G, March 11, 2019 Page 13
7.5. Wavelength Sensitivity
Figure 6 Wavelength Sensitivity Graph

Amplified MCT Detector Chapter 8: Mechanical Drawings
Page 14 21417-D02
Chapter 8 Mechanical Drawings

Amplified MCT Detector Chapter 9: Regulatory
Rev G, March 11, 2019 Page 15
Chapter 9 Regulatory
As required by the WEEE (Waste Electrical and Electronic Equipment Directive)
of the European Community and the corresponding national laws, Thorlabs offers
all end users in the EC the possibility to return “end of life” units without incurring
disposal charges.
This offer is valid for Thorlabs electrical and electronic equipment:
Sold after August 13, 2005
Marked correspondingly with the crossed out
“wheelie bin” logo (see right)
Sold to a company or institute within the EC
Currently owned by a company or institute
within the EC
Still complete, not disassembled and not
contaminated
As the WEEE directive applies to self-contained
operational electrical and electronic products, this end of
life take back service does not refer to other Thorlabs products, such as:
Pure OEM products, that means assemblies to be built into a unit by the
user (e.g. OEM laser driver cards)
Components
Mechanics and optics
Left over parts of units disassembled by the user (PCB’s, housings etc.).
If you wish to return a Thorlabs unit for waste recovery, please contact Thorlabs or
your nearest dealer for further information.
Waste Treatment is Your Own Responsibility
If you do not return an “end of life” unit to Thorlabs, you must hand it to a company
specialized in waste recovery. Do not dispose of the unit in a litter bin or at a public
waste disposal site.
Ecological Background
It is well known that WEEE pollutes the environment by releasing toxic products
during decomposition. The aim of the European RoHS directive is to reduce the
content of toxic substances in electronic products in the future.
The intent of the WEEE directive is to enforce the recycling of WEEE. A controlled
recycling of end of life products will thereby avoid negative impacts on the
environment.
Wheelie Bin Logo

Amplified MCT Detector Chapter 10: Thorlabs Worldwide Contacts
Page 16 21417-D02
Chapter 10 Thorlabs Worldwide Contacts
For technical support or sales inquiries, please visit us at
www.thorlabs.com/contact for our most up-to-date contact information.
USA, Canada, and South America
Thorlabs, Inc.
sa[email protected]
[email protected]
Europe
Thorlabs GmbH
[email protected]
France
Thorlabs SAS
[email protected]
Japan
Thorlabs Japan, Inc.
[email protected]
UK and Ireland
Thorlabs Ltd.
[email protected]
[email protected]
Scandinavia
Thorlabs Sweden AB
[email protected]
Brazil
Thorlabs Vendas de Fotônicos Ltda.
[email protected]
China
Thorlabs China
[email protected]

www.thorlabs.com