Plexon PlexBright Light User manual
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PlexBright®Light Measurement Kit Guide
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PlexBright®Light Measurement Kit Guide
Contents
3 Introduction
3 Overview
4 Components
5 Hardware Set-up
5 First Time Equipment Set-up
6 Preparing PlexBright Equipment to Be Measured
9 Measuring Steady-state Light Outputs
10 Dynamic/Pulsed Light Measurements
13 Appendix: Avoiding Light-clipping with PlexBright Photodetector Adaptors
Documentation History
Date Version Notes
September 2018 OPTTN0002e -Removed wand detector
June 2014 OPTTN0002d - Minor edits
May 2014 OPTTN0002c - Updated images and minor edits
March 2014 OPTTN0002b - Additional copy and minor edits
November 2013 OPTTN0002a - Initial creation of document
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Introduction
This document will provide a description of the PlexBright®Light Measurement Kit components and
instructions for proper usage with the PlexBright Optogenetic Stimulation System (PlexBright System).
Plexon provides the PlexBright Light Measurement Kit, containing the THORLABS PM100D Optical
Power and Energy Meter (PM100D Power Meter) and S140C Integrating Sphere Photodetector (S140C
Photodetector). This kit also includes adaptor pieces required to interface the S140C Photodetector with
PlexBright LED Modules and PlexBright Optical Patch Cables. If you have already purchased the S140C
Photodetector and a matching PM100D Power Meter, then you only need to purchase the necessary
photodetector adaptor kit from Plexon. (See Appendix for more information about why PlexBright
photodetector adaptor pieces are critical for accurate readings.)
This guide will provide a basic overview and describe components, hardware set-up, measuring steady-
state light outputs, dynamic/pulsed light measurements, and includes an Appendix on avoiding light-
clipping with PlexBright Photodetector Adaptors.
Overview
It is often useful to measure light outputs from the PlexBright System. For example, light output
measurements can validate proper functioning of a PlexBright LED Module and proper connection of any
attached PlexBright Optical Patch Cable and PlexBright Fiber Stub Implant. Also, because of variations
between PlexBright LED Modules, PlexBright Optical Patch Cables and PlexBright Fiber Stub Implants,
expected light outputs for a given supply current are only approximate. Light output measurements
enable the precise control of optical stimulation that is often required in optogenetics experiments.
Light output measurements typically require a photodetector and power meter. The photodetector
transduces incident light into an electrical signal, which the power meter processes and converts into a
reading of light intensity. Dierent power meter/photodetector combinations will enable measurements
of PlexBright light outputs, but the wrong components or even the incorrect use of the right components
may lead to inaccurate measurements.
To take measurements of light output from the PlexBright System, Plexon highly recommends use of the
PM100D Power Meter and S140C Photodetector along with specially designed PlexBright Photodetector
Adaptor pieces for the most accurate readings. Standard photodetector adaptors are often not designed
to anticipate the wide output angle of light emitted by the high performance PlexBright System. Thus, the
resulting readings are likely to under represent the true output. Using the PlexBright Light Measurement
Kit as described on the following pages will ensure you have the right equipment and techniques to make
the most accurate measurements.
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Components
The PlexBright Light Measurement Kit contains the following light measurement hardware from
THORLABS as well as custom Plexon adaptors required for accurate and simple measurements of light
output from PlexBright LED Modules, PlexBright Optical Patch Cables or PlexBright Fiber Stub Implants.
THORLABS Light Measurement Hardware
A - THORLABS PM100D Optical Power and Energy Meter B - THORLABS S140C Integrating Sphere
Photodetector
C - SMA-to-BNC Adaptor for outputting dynamic power
meter output to an oscilloscope
Plexon Photodetector Adaptors
D - PlexBright LC Photodetector Adaptor (08-14-A-01) for use with the PlexBright
Compact LED Modules or PlexBright Optical Patch Cables with an LC Ferrule Tip
E - PlexBright FC Connector Photodetector Adaptor (08-14-A-02) for use with the
PlexBright Table-top LED Modules
F - PlexBright FC Ferrule Photodetector Adaptor (08-14-A-03) for use with the
PlexBright Optical Patch Cables with an FC Ferrule Tip
Plexon can not guarantee the accuracy of any reading where dierent light measurement hardware has
been substituted. Also, please note that there is not a photodetector adaptor identied for use with
PlexBright Optical Patch Cables with a Bare Fiber Tip or PlexBright Fiber Stub Implants—that is because
an accurate measurement can be made without the need for an adaptor.
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Hardware Set-up
First Time Equipment Set-up
THORLABS System Equipment
1. Unpack the S140C Photodetector from the storage case.
2. Use a Phillips screwdriver (not included) to
remove any non-Plexon adaptors from the
S140C Photodetector, returning them to the
storage case for possible future use.
3. Unpack the PM100D Power Meter from its storage case.
4. Plug in the PM100D Power Meter using the included power supply or select to run from battery.
5. Firmly attach the connector of the S140C Photodetector into the port on the the
PM100D Power Meter marked “sensor”.
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Plexon Photodetector and SMA-to-BNC Adaptors Box
1. Unpack the Plexon Photodetector Adaptor
Equipment contained in a white Plexon box.
2. Use a Phillips screwdriver (not included) to attach the desired PlexBright Photodetector Adaptor to the
S140C Photodetector with the included screws (review “Plexon Photodetector Adaptors” options in
previous Components section).
Preparing PlexBright Equipment to be Measured
The PlexBright Photodetector Adaptors are designed to easily and accurately interface PlexBright LED
Modules and PlexBright Optical Patch Cables to the THORLABS S140C Photodetector. PlexBright
Photodetector Adaptors will be necessary for accurate measurements of output from PlexBright LED
Modules or PlexBright Optical Patch Cables with either an LC or FC Ferrule tip.
NOTE: Measuring output from PlexBright Optical Patch Cables with a Bare Fiber Tip
or from PlexBright Fiber Stub Implants does not require the use of an adaptor.
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Preparing PlexBright LED Modules
To measure light output directly from a PlexBright LED Module:
1. Clean and dry the ferrule tip rst (ideally using the PlexBright Optical Fiber Cleaning Kit).
2. Place the ferrule of the PlexBright LED Module into the opening on the appropriate PlexBright
Photodetector Adaptor:
- For PlexBright Compact LED Modules, the LC Photodetector Adaptor (08-14-A-01) should already be
attached (see “Plexon Photodetector SMA-to-BNC Adaptors Box” section under “Hardware Setup”).
- For PlexBright Table-top LED Modules, the FC Connector Photodetector Adaptor (08-14-A-02) should
already be attached (see“Plexon Photodetector SMA-to-BNC Adaptors Box” section under “Hardware
Setup”).
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Preparing PlexBright Optical Patch Cables
To measure light output from a PlexBright Optical Patch Cable with an LC or FC Ferrule tip connected to a
PlexBright LED Module:
1. Separate the module from the patch cable.
2. Clean and dry the ber exiting the module, and the ber tips at both ends of the patch cable (ideally
using the PlexBright Optical Fiber Cleaning Kit).
3. After reattaching the module to the patch cable, make sure the patch cable is properly and rmly
attached to the module.
4. Place the exposed ferrule of the PlexBright Optical Patch Cable into the opening on the appropriate
PlexBright Photodetector Adaptor already xed to the photodetector:
- For PlexBright Optical Patch Cables with an LC Ferrule Tip, the LC Photodetector Adaptor
(08-14-A-01) should already be attached (see“Plexon Photodetector SMA-to-BNC Adaptors Box”
section under “Hardware Setup”).
- For PlexBright Optical Patch Cables with an FC Ferrule Tip, the FC Ferrule Photodetector Adaptor
(08-14-A-03) should already be attached (see“Plexon Photodetector SMA-to-BNC Adaptors Box”
section under “Hardware Setup”).
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To measure light output from a PlexBright Optical Patch Cable with a Bare Fiber tip
connected to a PlexBright LED Module:
1. Separate the module from the patch cable.
2. Clean and dry the ber exiting the module, and the ber tips at both ends of the
patch cable (ideally using the PlexBright Optical Fiber Cleaning Kit).
3. After reattaching the module to the patch cable, make sure the patch cable is
properly and rmly attached to the module.
4. No PlexBright Photodetector Adaptor is needed. Simply x the PlexBright Optical
Patch Cable over the direct center of the S140C Photodetector’s aperture with a
stabilizing device rather than freely holding it.
Preparing PlexBright Fiber Stub Implants
No Photodetector Adaptor is required to measure light output from a PlexBright Fiber Stub Implant
(connected to a PlexBright Optical Patch Cable and a PlexBright LED Module). To measure light output
from a bare ber at the end of a PlexBright Fiber Stub Implant:
1. Remove any adaptor from the S140C Photodetector.
2. Separate the module, the patch cable and the ber stub implant (if applicable).
3. Clean and dry the ferrule exiting the module, and the ber tips at both ends of the patch cable and/or
the ber stub implant (ideally using the PlexBright Optical Fiber Cleaning Kit).
NOTE: Be careful not to damage the fragile glass tip of the ber stub when cleaning or positioning.
4. No PlexBright Photodetector Adaptor is needed. Simply x the PlexBright Fiber Stub Implant over the
direct center of the S140C Photodetector’s aperture
Measuring Steady-state Light Outputs
The PM100D Power Meter provides a simple push-button interface that displays the measured light power.
Typical units of measurement are milliwatts (mW).
1. Congure the PM100D Power Meter for the wavelength being measured. The current wavelength
setting is displayed in the lower left corner of the screen. Press the λ button to access the “Wavelength”
menu. Use the arrow keys to select one of the default wavelengths, or if necessary customize one of the
defaults by pressing and holding the OK button to enter editing mode. In edit mode, use the arrow keys
to set the desired wavelength and then press OK.
NOTE: Failure to set the appropriate wavelength will result in faulty readings of light output.
Select the wavelength of the light being measured
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2. Make sure the tip of the PlexBright LED Module or PlexBright Optical
Patch Cable with a Ferrule tip is clean and fully inserted into the
appropriate PlexBright Photodetector Adaptor.
NOTE: If measuring output from a PlexBright Optical Patch Cable with
a Bare Fiber Tip or a PlexBright Fiber Stub Implant, a Photodetector
Adaptor is not necessary. Use a manipulator to x the optical ber tip
just inside the direct center of the S140C Photodetector’s aperture.
3. Observe the output reading from the PM100D Power Meter.
4. To obtain units of mW/mm2at the tip of optical ber, divide the mW measurement by the cross-sectional
area of the ber core.
- For any PlexBright Optical Patch Cable, the core radius is
0.1mm. Therefore, the cross sectional area is 0.0314mm2.
- For PlexBright Fiber Stub Implants with the larger optical ber (200/230μm), the core radius is
0.1mm. The cross sectional area is 0.0314mm2 (same as above).
- For PlexBright Fiber Stub Implants with the smaller optical ber (110/125μm), the core radius is
0.055mm. Therefore, the cross sectional area is 0.0095mm2.
For example, a PlexBright Optical Patch Cable generating a reading of 25mW would be converted to
mW/mm2as follows:
25mW / (0.0314mm2) = 796 mW/mm2
Dynamic/Pulsed Light Measurements
The display on the PM100D Power Meter is not suitable for visualizing quickly changing light outputs.
However, the PM100D Power Meter provides an analog output signal that can be routed to an
oscilloscope to characterize dynamic light outputs. The following materials are required:
SMA-to-BNC Adaptor (included)
Standard female-to-female BNC cable (not included)
Standard oscilloscope (not included)
Sample Oscilliscope
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To measure quickly changing light outputs take the following steps:
1. Attach SMA-to-BNC Adaptor rmly to the“ANALOG OUT” of the PM100D Power Meter.
2. Attach a standard BNC cable from the SMA-to-BNC Adaptor to the oscilloscope input.
3. Select the wavelength being measured as described in the Measuring Steady-state Light Outputs
section.
4. Under the “Measurement Conguration”menu of the PM100D Power Meter’s push button interface,
select the “BW HI” (high bandwidth) option. This option will enable high frequency outputs.
SMA-to-BNC Adaptor
SMA Port
SMA-to-BNC Adaptor
attached to port
BNC Cable to Oscilloscope
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5. Under the “Rng” menu, disable the autoranging feature by selecting from the drop down list the maximum light
output to be measured. This step is important to keep the scaling of the output signal constant. Take note of this
maximum range value (e.g. 140mW).
6. The analog output displayed on the oscilloscope (volts) must be converted to a light measurement
(watts), taking into account the maximum range value, which in turn depends on the set wavelength:
Oscilloscope Reading (mV) / 2000 (mV) * Maximum Range Value (mW) = Light Output (mW)
For example, if the oscilloscope reading of light output is
400mV, with the PM100D Power Meter set to measure a
wavelength of 465nm and the maximum range value selected
to be 140mW, then the light output is:
400/2000 * 140 = 28mW
7. To visualize and measure short pulses or quickly changing
signals, use the trigger setting on the oscilloscope.
When an oscilloscope is not available, the maximum value reading on the front display of the light meter (MAX
RESET) may be used to capture the peak value of quickly changing light pulses. For further information, consult
Section 5.3: Power Measurement of Pulsed Signals in the THORLABS PM100D Operation Manual.
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Appendix: Avoiding Light-clipping with PlexBright Photodetector Adaptors
Photodetectors often come with adaptors designed to mate with standard ber-optic connectors.
However, these adaptors are often not designed to anticipate the wide output angle of light emitted
by the high performance PlexBright System. As a result, these standard adaptors can clip the light
output from PlexBright devices, causing articially low measurements. To avoid this, use the appropriate
PlexBright Photodetector Adaptor when possible. (An adaptor is not necessary when measuring output
from PlexBright Optical Patch Cables with a Bare Fiber Tip or PlexBright Fiber Stub Implants.) The
emitting tip of the PlexBright LED Module or PlexBright Optical Patch Cable can also be manually
positioned by hand or with a manipulator to avoid light clipping.
Left) The adaptor is designed to measure a narrow output
cone of light. Right) Wider angle light is clipped by the same
adaptor and never reaches the photodetector surface.
About Plexon Inc
Plexon is a pioneer and leading innovator of custom, high-performance data acquisition, behavior and analysis solutions specically designed
for scientic research. We collaborate with and supply thousands of customers including the most prestigious neuroscience laboratories
around the globe driving new frontiers in areas including basic science, brain-machine interfaces (BMI), neurodegenerative diseases, addictive
behaviors and neuroprosthetics. Plexon oers integrated solutions for in vivo neurophysiology, optogenetics, and behavioral research – backed
by its industry-leading commitment to quality and customer support. For more information, please visit www.plexon.com.
Sales Support
For Sales Support, email info@plexon.com or call +1 (214) 369-4957.
Technical Support
If after reviewing this document, you would still like to access Plexon’s Technical Support, we are available via several communication channels.
You are invited to reach us through email or on the phone.
EMAIL PHONE
+1 (214) 369-4957
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PLEXON®, the ve-line symbol, CereStage™, CinePlex®, DigiAmp™, MiniDigi™, Oine Sorter™, OmniPlex®, PL2™, PlexBright®, PlexDrive™,
PlexStim™, Radiant™ and RapidGrid™ are registered and unregistered trademarks of Plexon Inc, Dallas, Texas, USA. ©2018 Plexon Inc. All
rights reserved. Other product and company names mentioned are trademarks of their respective owners.
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