PE50BF-DIF-C | Pyroelectric Sensors | Laser Energy Sensors - Ophir



The PE50BF-DIF-C is a pyroelectric energy meter with a diffuser for concentrated beams. It has a 35mm aperture and can measure energies from 200µJ up to 10J. It can operate at repetition rates up to 250Hz and covers the spectral range from 0.19 - 2.2, 2.94µm. The sensor comes with a standard 1.5 meter cable for connecting to a meter or PC interface.


  • BF with diffuser
  • Ø35mm
  • 0.19-2.2µm, 2.94µm
  • 200µJ-10J
  • 250Hz
  • Ø62 W x 35 D (mm)
  • 10J
  • 200W/cm²
  • 20 ms
  • 4J/cm²
  • 60J/cm²
  • 25W
  • CE, China RoHS
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How should I clean my sensor?

First, clean the absorber surface with a tissue, using Umicore #2 Substrate Cleaner, acetone or methanol. Then dry the surface with another tissue. Please note that a few absorbers (Pyro-BB, 10K-W, 15K-W, 16K-W and 30K-W) cannot be cleaned with this method. Instead, simply blow off the dust with clean air or nitrogen. Don't touch these absorbers. Also, HE sensors (such as the 30(150)A-HE-17) should not be cleaned with acetone.
Note: These suggestions are made without guarantee. The cleaning process may result in scratching or staining of the surface in some cases and may also change the calibration.

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Are pyro sensors suitable for power measurement and if so, what is the accuracy?

All Ophir pyroelectric sensors can measure average power with Ophir Power and Energy Meters. The instrument measures the number of pulses each second and multiplies the energy reading by the pulse rate. If the pulse rate is constant, then the accuracy of power measurement will be the same as the energy accuracy since the pulse rate measurement is very accurate.

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What is the "User Threshold" feature on the Pyro-C series and how does it work?

The Pyro-C sensors have a "user threshold" feature allowing the user to adjust the measurement threshold in noisy environments. Increasing the threshold will prevent triggering on noisy signals and allow accurate measurment of energy and frequency, as long as the laser pulses are larger than the noise.


The trigger level can be adjusted up to 25% of full scale, however operation depends on the pulse width setting. For pulse width settings below ~0.25ms, the minimum energy that can be measured accurately is approximately 40% above the user threshold setting. Pulses below this energy level will trigger the sensor down to the user threshold level, but accuracy is compromised.


For pulse width settings above ~0.25ms, accuracy is good all the way down to the threshold. If the laser pulse width is less than 1/2 the setting, the minimum energy corresponds to the setting. However, with longer laser pulse widths, the minimum energy will be higher, rising to approximately twice the user threshold level when the laser pulse width is equal to the sensor pulse width setting.


It is recommended always to set the user threshold to the minimum possible setting to retain best energy accuracy in any given situation. See the user manual for further information on how to use the user threshold.

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How does the pyroelectric sensor behave for pulsed radiation at a frequency which is over the data sampling rate?

The Power and Energy Meters simply decides it is time for a sample and takes the next pulse that comes after that time, e.g. if it samples at 400 Hz, then every 1/400th of a second it is ready to take the next pulse that comes along.

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Can I use a PE-C pyroelectric sensor for higher powers for a short time without the optional heat sink?

The catalog specification states the maximum power a sensor can be used with and without the heat sink. The purpose of the heat sink is to keep the sensor temperature below the maximum permitted at higher average powers. If you use the sensor for a short time only, on the order of 1-2 minutes at a time, you should be able to measure up to the higher power given in the spec even without the heat sink.

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Are Pyro-C energy sensors compatible with all Ophir meters?

Yes, with certain limitations. Here are the points to be aware of:
Vega, Nova II, StarLite, StarBright meters and Juno PC interface: Full support of all features
All other instruments (Nova/Orion and LaserStar meters, as well as USBI, Pulsar, and Quasar PC interfaces): Support the Pyro-C sensors, except for the following features: Only 2 of the 5 pulse width settings are available.
User selectable threshold is not available.
In addition to the above: When using a Pyro-C sensor with the Nova (or Orion) meter, the "Nova PE-C Adapter" (Ophir p/n 7Z08272) is required. 

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Do I need to recalibrate my instrument? How often must it be recalibrated?

Unless otherwise indicated, Ophir sensors and meters should be recalibrated within 18 months after initial purchase, and then once a year after that.

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Can a laser measurement depend on the distance from the laser to the sensor?

In theory, if a beam is completely parallel and fits within the aperture of a sensor, then it should make no difference at all what the distance is; it will be the same number of photons (ignoring absorption by the air, which is negligible except in the UV below 250nm). If, nevertheless, you do see such a distance dependence, there could be one of the following effects happening:

  • If you are using a thermal type power sensor, you might actually be measuring heat from the laser itself; when very close to the laser, the thermal sensor might be “feeling” the laser’s own heat. That would not, however, continue to have an effect at more than a few cm distance unless the light source is weak and the heat source is strong.
  • Beam geometry – The beam may not be parallel and may be diverging. Often, the lower intensity wings of the beam have greater divergence rate than the main portion of the beam. These may be missing the sensor's aperture as the distance increases. To check that you'd need to use a profiler, or perhaps a BeamTrack PPS (Power/Position/Size) sensor.
  • If you are measuring pulse energies with a diffuser-based pyroelectric sensor: Some users find that when they start with the sensor right up close to the laser and move it away, the readings drop sharply (typically by some 6%) over the first few cm. This is likely caused by multiple reflections between the diffuser and the laser device, which at the closest distance might be causing an incorrectly high reading. You should back off from the source by at least some 5cm, more if the beam is not too divergent.

Needless to say, it’s also important to be sure to have a steady setup; a sensor held by hand could easily be moved around involuntarily, which could cause partial or complete missing of the sensor’s aperture at increasing distance, particularly for an invisible beam.

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What are the differences between the old pyro sensors and the current “PE-C” line of pyro sensors? I can only find scattered information in the specs.

The old pyro sensors and the newer PE-C sensors are almost identical; the differences between them are as follows:

  1. More compact
  2. User Threshold – minimum energy threshold (below which the sensor will not trigger) can be selected according to users' needs
  3. Measures longer pulses (up to 20ms depending on model)
  4. Has up to 5 pulse width settings as opposed to only 2 pulse width settings

Smaller size and therefore:

  • May need a heat sink (P/N 7Z08267) in order to stand up to higher average powers
  • May need a mechanical size adapter (P/N 7Z08273) if it must fit into an existing mechanical jig designed for the older models

Meters and Software Support:
StarLite, Juno, Vega, & Nova II fully support the Pyro-C series. Laserstar, Pulsar, USBI, Quasar, and Nova / Orion with adapter* partially support the Pyro-C series:

  • Only 2 of the 5 pulse width settings are available
  • Lowest measureable energy cannot be selected (no User Threshold).

StarLab software supports both Pyro-C and older pyro series.

*Note: The PE-C series will only operate with Nova / Orion meters with an additional adapter Ophir P/N 7Z08272 (see details in Ophir website).

Wavelength Setting Names:
If you have your own software for communicating with the sensor, it may be important to note that for some models, the names of the wavelength settings are a bit different between the old pyro and the new PE-C, even though they mean exactly the same thing.

For example, with diffuser OUT, the settings in the PE50BB-DIF-V2 are called “<.8u” (i.e. visible, represented by a calibration point at 532nm that covers the full visible range), and “106” (i.e. 1064nm), while in the PE50BB-DIF-C these same settings are called “532” (i.e. 532nm, the calibration point for the visible) and “1064”.

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When logging pulse energy measurements on a PC using StarLab, what is the time resolution of the timestamps?

When logging energy measurements on a PC with the StarLab software from a Pyro sensor via either a Nova-II, or Vega, or a USB enabled StarLite meter, the timestamp for each Energy pulse measured in the log is provided entirely by the clock on the PC which has millisecond resolution. (Note: Because a timestamp provided by a multitasking Windows PC is not from a true real time system, there could be instances where the timestamp is not well synced with the actual energy pulse measurement in the log, depending on how ‘burdened’ the computer was at any particular moment.)

When logging energy measurements on a PC with the StarLab software from a Pyro sensor via either a StarBright, Juno or Pulsar, each of these meters provides a precise microsecond resolution timestamp from their on-board clock.

This timestamp is synced to the Energy measurement and the data is written together in the log. The precise on-board clock in the StarBright, Juno or the Pulsar is used here to determine the time differences between measurements - rather than the PC clock which is used here just to set the initial baseline time of the log. This is the best method to log Energy if timing of pulses is critical.

As opposed to Pyro Energy measurements, when logging Power measurements on a PC via StarLab with either Photodiode or Thermopile sensors, where fast measurements are not required anyway, the log timestamp is provided entirely by the millisecond resolution clock on the PC when connected to any of our meters.

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  • PE-C sensors with StarLab

    Support for PE-C sensors with Vega, Nova II, Juno, EA-1, StarLite and StarBright in StarLab application is now available.
    When working with other meters and interfaces it is not necessary to update the embedded software of the PE-C.

    Download Steps
    In order to upgrade the embedded software in the PE-C sensor with the StarLab application:

    • Attach the PE-C sensor to a Juno (version 1.21 or higher), a Vega / Nova-II (version 2.16 or higher), a StarLite (version 1.22 or higher) or a StarBright (version 1.30 or higher).
         To download the latest version of Juno, Vega, Nova-II, StarLite or StarBright firmware press here
    • Connect the meter to the PC and run StarLab (with version 3.20 or higher).
         To download the latest StarLab version press here
    • Enter the diagnostic screen and select to upgrade sensor firmware (version 1.69 or higher).
         To download the latest PE-C version press here

    Note: PE-C sensors can't be upgraded via EA-1 interface.




Tech Tip: Laser Measurement Affected by Distance Tech Tip: Laser Measurement Affected by Distance
Sensors for Measuring Laser Energy Sensors for Measuring Laser Energy Sensors for Measuring Laser Energy

In this short “Basics” video, we review in general the use of pyro-electric sensors for measuring laser pulse energies.

Energy Sensors: Response Time, Integration Time… Energy Sensors: Response Time, Integration Time… Energy Sensors: Response Time, Integration Time…

Confusion time?...
There seems to be a good deal of confusion when it comes to the terms “Response time” and “Integration time” of energy sensors.
In this article we will clarify the meaning of these terms, as they apply to Ophir’s pyro-electric “Smart Sensors”.

Peak power vs. Average Power – What is it, and how do I measure it? Peak power vs. Average Power – What is it, and how do I measure it? Peak power vs. Average Power – What is it, and how do I measure it?

A pulsed laser could have an average power of, say, 1 Watt, yet a peak power of 1 Megawatt – so when specifying it’s rather important to understand the difference! In this video you will learn what exactly these 2 concepts mean. You’ll also learn how to measure Peak Power, which can sometimes be tricky.

Calculate theoretical peak power with the peak power calculator

Can a laser measurement depend on the distance from the laser to the sensor?
The answer is…well, it’s not supposed to. But sometimes it does.
In this video, you’ll learn what could make that happen - and what to do about it.


Tutorials and Articles

Laser Energy Sensors introduction

Ophir has two types of energy sensors, pyroelectric and RP. Pyroelectric sensors are for measuring repetitive pulse energies and average powers at pulse rates up to 25000 pulses per second and pulse widths up to 20ms. RP sensors are specialty items mainly for very long pulse widths and very high average powers that cannot be measured by pyroelectric sensors. Note that single shot energy with pulse rates less than one pulse every 5s or so can be measured with thermal sensors described in the power sensor section


Common Reasons for Pyroelectric Sensor Damage or Out of Tolerance Conditions

This document was created to assist our valued customers in the proper care and maintenance of Ophir-Spiricon pyroelectric laser power sensors. The following information is for reference only. If you have any reason to believe that the sensor is no longer performing within the original specifications, we always recommend that you send it in for repair and/or recalibration by our trained technicians to bring the unit back to the proper NIST traceable standards. We believe that Ophir pyroelectric sensors can be used for many years without repair when used with the proper laser optical Read more...

How to Properly Select a Laser Power or Energy Sensor

The selection of a sensor to accurately measure the power of a laser or energy of a pulsed laser can seem like a simple and easy procedure. However, many times the selection process is limited to choosing a sensor that only meets the range of power or energy to be measured, leaving out several other essential criteria of the laser specifications; that without their consideration, can allow the wrong sensor to be selected, the laser to be measured inaccurately and likely to cause the sensor to fail prematurely.

Watch Our Laser Measurement Video


Power/Energy Meters: Why Damage Specs are Derated for Larger Beams

For certain pyro sensors with a diffuser, such as the PE50BF-DIF-C P/N 7Z02941, there is a Note (b) that for 10mm beam size the damage threshold specification should be derated by 50%. To explain why the damage specification is derated for a larger beam size, please see the picture illustration below. This has to do with the smaller relative increase in spot size lowering the energy density less on a larger beam than the larger relative increase in spot size with a smaller beam lowering the energy density more Read more...

Effect of Ambient Conditions on Laser Measurements

We are often asked about the specified ranges of various ambient conditions (temperature, humidity, etc.) for Ophir instruments. In this article we will clarify the effects of these conditions on laser measurements, so you’ll be able to use your Ophir laser measurement instrument effectively.


Ophir Power/Energy Meter Calibration Procedure and Traceability/Error Analysis

This document discusses the interpretation and basis for stated measurement accuracy of Ophir Laser Power/Energy meters.
1. General Discussion
2. Combination of Errors and Total Error
3. Analysis of Power and Energy Calibration Errors
4. Detailed Analysis of Power and Energy Calibration Errors


Laser Measurements in Materials Processing: How and When They Absolutely, Positively Must Be Made

19th century British physicist and engineer William Thomson, 1st Baron Kelvin, was the first to say, “If you can’t measure it, you can’t improve it.” When applying this principle to improving laser-based processes, there are a variety of parameters that must be measured. Given the continuously rising power of laser systems in material processing, the requirements for measurement systems are more challenging than ever. Which technologies are available to measure high-power lasers? How often should they be measured? What measurements should be tracked? When this data is collected, what should be done with it? Read more...

Types of power / Energy Laser Sensors General Introduction

Power and Single Shot Energy Sensors
Ophir provides two types of power sensors: Photodiode sensors and Thermal sensors. Photodiode sensors are used for low powers from picowatts up to hundreds of milliwatts and as high as 3W. Thermal sensors are for use from fractions of a milliwatt up to thousands of watts.
Thermal sensors can also measure single shot energy at pulse rates not exceeding one pulse every ~5s.

Repetitive Pulse Energy Sensors
For higher pulse rates, Ophir has pyroelectric energy sensors able to measure pulse rates up to tens of KHz. These are described in the energy sensor section, section 1.3.


Oscilloscope Adapter for Ophir Pyroelectric Sensors Ophir P/N 7Z11012

IntroductionOphir Pyroelectric Energy Sensors and Photodiode Energy Sensors can measure pulse energy from pico-Joules to 10's of Joules, and up to 25kHz pulse rates. They support pulse widths from nanoseconds or below, up to 20ms. They are compatible with most Ophir Meters and PC Interfaces, including the Nova II, Vega, StarLite, StarBright, Centauri, Juno and EA-1 meters. Most of the time, measurements in digital format are adequate, either in the form of measurements displayed on a screen, or data logged into a log file using Ophir's StarLab software. But sometimes it is Read more...

5 Situations Where Laser Performance Measurement is Necessary

Measuring the performance of a laser has possible for a number of years and is accomplished with a variety of techniques. These electronic laser measurement solutions give the laser user more relevant, time-based data that shows trends in laser performance rather than single data points. While these solutions have provided laser users with the ability to present data in a simple and easy to understand manner, the application of the data still seems to be unclear to many laser users. Read more...


Customers that purchase the above items also consider the following items. Ophir-Spiricon meters and sensors include a standard manufacturers warranty for one year. Add a one year Extended Warranty to your meter or sensor, which includes one recalibration.
  • Heat Sink

    Heat Sink


    Heat sink that screws onto rear of PE-C series sensors allowing working at over 50% higher average powers

  • Scope Adapter

    Scope Adapter


    Plugs in between the PE sensor and power meter.
    Provides BNC output to scope to see every pulse up to
    the maximum frequency of the sensor.

  • Beam splitter for PE and Thermal sensors

    Beam Splitter Assembly to measure pulsed laser sources
    too energetic for direct measurement. The reading with
    the Beam Splitter can be calibrated by setting the laser to
    a lower energy that will not damage the sensor and then
    taking a measurement with the beam splitter and without
    and taking the ratio.

  • PE Test Plates (BF)

    Test plates with same absorber coating as the sensor. For
    testing that laser beam is not above damage threshold
    (1 such plate is included with sensor package).

  • Nova PE-C Adapter

    Nova PE-C Adapter


    The adapter plugs between the Nova D15 socket and the smart plug of the PE-C sensor to allow the Nova to operate with PE-C series sensors. See PE-C spec sheet for details.

  • PE-C to PE Size Adapter

    The newer PE-C series sensors have a φ62mm diameter.
    The older PE series sensors have a φ85mm diameter. This
    adapter allows using the PE-C type sensors in jigs and
    setups that were originally designed for PE sensors.

  • 3m Cable

    3m Cable


    3m cable to connect sensor to power meter or interface. Order along with sensor to receive this instead of the standard 1.5m cable.

  • Cable

    5m Cable


    5m cable to connect sensor to power meter or interface. Order along with sensor to receive this instead of the standard 1.5m cable.

  • 10m cable

    10m Cable


    10m cable to connect sensor to power meter or interface. Order along with sensor to receive this instead of the standard 1.5m cable.

  • Extended Warranty for Sensor


    Ophir-Spiricon meters and sensors include a standard manufacturers warranty for one year. Add a one year Extended Warranty to your meter or sensor, which includes one recalibration. More info