Short Pulse 15 µW to 3 W Thermopile Sensor with Ø12 mm Aperture

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Overview

The 3A-P thermopile sensor is a very sensitive laser power and energy thermal sensor for short pulsed lasers. It has a 12 mm aperture. It can measure optical power from 15 µW to 3 W and energy from 20 µJ to 2 J. It has the P type volume absorber and covers the spectral range from 0.15 to 8 µm.

P type high sensitivity short pulse 0.15 to 8 µm absorber
15 µW to 3 W power measurement range
20 µJ to 2 J energy measurement range
Very low noise and drift
Fiber optic adapters available

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Products

		Compare	Model	Compatibility	sortOrder	rankScore	ranking	Drawings, CAD & Specs		Absorber Type	Aperture Size	Minimum Power	Maximum Average Power	Availability	Featured Item	Price		Brand
		7Z02622 3A-P Thermal Laser Power Sensor, P Type, 15 µW to 3 W, Ø12 mm Aperture, 0.15-8 µm $1,275 4 Weeks	7Z02622 3A-P Thermal Laser Power Sensor, P Type, 15 µW to 3 W, Ø12 mm Aperture, 0.15-8 µm	UNIVERSAL	0.0	1.0	0.0		0.0	P - Short pulse	Ø12 mm	15 µW	3 W	4 Weeks		$1,275		Ophir

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Notes:

If you need to measure position in addition to power, we offer the 3A-P-QUAD BeamTrack version of this sensor.

Specifications

Product Name

3A-P
Absorber Type

P - Short pulse
Aperture Size

Ø12 mm
Spectral Range

0.15 to 8 µm
Minimum Power

15 µW
Maximum Average Power

3 W
Minimum Pulse Energy

20 µJ
Maximum Pulse Energy

2 J
Response Time

2.5 s

Maximum Average Power Density

0.05 kW/cm²
Maximum Energy Density <100 ns

1 J/cm²
Maximum Energy Density 2 ms

1 J/cm²
Cooling

Convection
Dimensions

Ø70 x 30 mm
Cable Length

1.5 m
CE Compliance

Yes
UKCA Compliance

Yes
China RoHS Compliance

Yes

Features

Choosing a Thermal Sensor

In this short “Basics” video we review the use – and selection - of thermal sensors for measuring low, medium and high laser powers.

Sensors for Measuring Laser Power

In this short "Basics" video we review in general how one goes about measuring laser beam power, so that you'll have a clear understanding of what the different sensor types are, and when to use each type.

Thermal Power Sensor Accuracy

Ophir former CTO Dr. Ephraim Greenfield discusses the various factors that contribute to uncertainties in measurement when using Ophir laser power and energy meters.

Effects of Incidence Angle on Measurements

In this video, you will learn to what degree a beam’s incidence angle matters, and for which sensor types this should be taken into account.

Thermal Sensor Calibration

As the spectral sensitivity of the absorber used for the power and energy measurement is not fully linear, Ophir sensors get a high precision calibration by default with more than one wavelength.

Each thermal sensor is calibrated independently of a particular Ophir power meter with its calibration information contained in the DB15 plug. When the sensor is connected to the meter, the meter reads and interprets this information to display a calibrated reading. Each power meter is calibrated independently and has the same sensitivity as an other meter within about 2 tenths of a percent.

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

Absorption of different thermal sensor absorber types

Frequently Asked Questions

Will the 3A-P sensor work at 10.6µm?
Answer
The 3A-P actually absorbs about 85% at 10.6µm and therefore it can be used to measure weak CO2 lasers. Note the low power damage threshold, however, of 50W/cm².

How should I clean my sensor?
Answer
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.

If according to the catalog specs or the sensor finder I am very close to the damage threshold but below it, should I choose such a sensor?
Answer
It is not recommended to choose a sensor if it is very close to the damage threshold if there is an alternative, since laser damage is not an exact figure and depends on many things. Use the Sensor Finder to find the best match where you are preferably below 50% of the damage threshold.

How do you calculate the power and energy density of a laser beam?
Answer
If the power is P and the diameter of the beam is D then the power density is P /(.785 * D²) . If it is a pulsed laser and the energy is E, the repetition rate is R and the diameter is D then the power density is E*R/(.785 * D²), The energy density is E/(.785 * D²). The sensor finder will automatically calculate the power and energy density.

When an accuracy spec is given, what exactly is meant?
Answer
The Ophir specification on accuracy is in general 2 sigma standard deviation. This means, for instance, that if we list the accuracy as +/-3%, this means that 95% of the sensors will be within this accuracy and 99% will be within +/-4%. For further information on accuracy see calibration procedure tutorial.

Do I need to recalibrate my instrument? How often must it be recalibrated?
Answer
Unless otherwise indicated, Ophir sensors and meters should be recalibrated within 18 months after initial purchase, and then once a year after that.

Does the damage threshold depend on power level?
Answer
The damage threshold of thermal sensors does depend on the power level and not only the power density because the sensor disc itself gets hotter at high powers. For instance, the damage threshold of the Ophir broadband coating may be 50KW/cm2 at 10 Watts but only 10KW/cm2 at 300W. The Ophir specifications for damage threshold are always given for the highest power of use of a particular sensor, something which is not done by most other manufacturers. This should be taken into account when comparing specifications. The Sensor Finder takes the power level into consideration when calculating damage threshold.

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

Frequently Asked Questions

Will the 3A-P sensor work at 10.6µm?
Answer
The 3A-P actually absorbs about 85% at 10.6µm and therefore it can be used to measure weak CO2 lasers. Note the low power damage threshold, however, of 50W/cm².

How should I clean my sensor?
Answer
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.

If according to the catalog specs or the sensor finder I am very close to the damage threshold but below it, should I choose such a sensor?
Answer
It is not recommended to choose a sensor if it is very close to the damage threshold if there is an alternative, since laser damage is not an exact figure and depends on many things. Use the Sensor Finder to find the best match where you are preferably below 50% of the damage threshold.

How do you calculate the power and energy density of a laser beam?
Answer
If the power is P and the diameter of the beam is D then the power density is P /(.785 * D²) . If it is a pulsed laser and the energy is E, the repetition rate is R and the diameter is D then the power density is E*R/(.785 * D²), The energy density is E/(.785 * D²). The sensor finder will automatically calculate the power and energy density.

When an accuracy spec is given, what exactly is meant?
Answer
The Ophir specification on accuracy is in general 2 sigma standard deviation. This means, for instance, that if we list the accuracy as +/-3%, this means that 95% of the sensors will be within this accuracy and 99% will be within +/-4%. For further information on accuracy see calibration procedure tutorial.

Do I need to recalibrate my instrument? How often must it be recalibrated?
Answer
Unless otherwise indicated, Ophir sensors and meters should be recalibrated within 18 months after initial purchase, and then once a year after that.

Does the damage threshold depend on power level?
Answer
The damage threshold of thermal sensors does depend on the power level and not only the power density because the sensor disc itself gets hotter at high powers. For instance, the damage threshold of the Ophir broadband coating may be 50KW/cm2 at 10 Watts but only 10KW/cm2 at 300W. The Ophir specifications for damage threshold are always given for the highest power of use of a particular sensor, something which is not done by most other manufacturers. This should be taken into account when comparing specifications. The Sensor Finder takes the power level into consideration when calculating damage threshold.

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

Accessories

Fiber Connector Adapters

These adapters allow for power measurement of connectorized fiber-optic cables. The sensor may need an additional mounting bracket to connect to these fiber adapters.

Description	Compatibility	Avail.	Price
7Z08227 SC Fiber Connector Adapter, Power and Energy Sensors	UNIVERSAL	In Stock	$302
7Z08226 ST Fiber Connector Adapter, Power and Energy Sensors	UNIVERSAL	In Stock	$264
7Z08229 FC Fiber Connector Adapter, Power and Energy Sensors	UNIVERSAL	In Stock	$153
1G01236A SMA Fiber Connector Adapter, Power and Energy Sensors	UNIVERSAL	In Stock	$74

Sensor Connector to BNC Adapter

The SH to BNC Adapter allows the connection of an Ophir sensor to a current or voltage measuring device for measurement of the raw sensor analog output. A current meter should be used for photodiode sensors. Current or voltage meters can be used for thermal sensors.

	Compare	Description	Compatibility	Drawings, CAD & Specs	Avail.	Price
		7Z11010 BNC Adapter, DB15 Optical Sensor Connector	UNIVERSAL		In Stock	$92

Extended Warranty for Sensor

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.