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Thermal Sensors

Ideal for measuring the average power from high power lasers

Download Datasheets	Knowledge Base
» High Sensitivity Thermopile	» Thermopile Spectral Absorption Chart
» Air-Cooled Thermopile (up to 150W)	» Measuring Long Pulse Energy
» Water-Cooled Thermopile (up to 150W)
» Fan-Cooled Thermopile (up to 300W)
» High Power Water-Cooled Thermopile (up to 10kW)
» Large Area Water-Cooled Thermopile (up to 5kW)
» Quadrant Air-Cooled Position Sensing Thermopile (up to 100W)
» Quadrant Water-Cooled Position Sensing Thermopile (up to 5kW)
» Volume Absorbing Thermopile

Thermal sensors are best suited for measuring CW laser power, average power in pulsed lasers or the energy of long pulses. A variety of thermal sensors is offered to suit different powers, beam size (etc). Thermal sensors (also called thermopiles) work over an extremely broad spectral range, as well as over a wide range of input powers. Thermal sensors also offer very uniform spatial response and are unaffected by changes in beam size, position or uniformity. Thermal sensors have uncompensated response times on the order of 1-45 seconds, depending upon sensor size. Electronic compensation within most meters results in 1-10 second response times. Thermal sensors are offered with a choice of apertures up to 200mm and are cooled by conduction, convection, forced air (fan cooling) or water cooling.

Thermopile sensors are compatible with all power and energy meter displays. Please note that the beam position capability of LM-series thermal sensors can only be utilised when connected to a LabMax meter. Selected thermopile heads are also available as PowerMax-USB sensors with the power meter electronics reduced in size to a USB connector.

Thermopile heads are offered with a choice of surface and volume absorbing sensors. Surface absorbing thermopile sensors are coated with a choice of finishes to suit different laser types:

• Black – this coating is applied to the high sensitivity, amplified thermopile sensors
• Broadband – this coating is applied to most of the air, fan and water-cooled sensors and possesses a higher damage threshold for both pulsed and CW lasers
• Excimer (UV) – this coating is optimised for use with excimer lasers
• HTD / H – the broadband coating applied to the quadrant, position sensing thermopile sensors

Volume absorbing thermopile sensors are fitted with a special diffuser to withstand the high peak powers from Q-switched or other high peak power lasers.

The relatively slow response of thermal sensors renders them unsuitable for measuring the energy per pulse from repetitively pulsed lasers. Instead, thermopile sensors can be used for measuring the average power from such lasers. For lasers which emit a single, long pulse, thermal sensors can be used to measure the energy from the pulse in Joules. For an explanation of this, download the technical note on measuring long pulse energy.

High Sensitivity Thermopile Sensors

The PS-series sensors offer a thermally stabilised, amplified power sensor with a broad spectral response, high sensitivity, and large active area. These sensors are ideal for laser diodes, diode bars and stacks, HeNe, HeCd and small ion lasers. For optimum performance at low power levels we recommend the PS10Q and PS19Q, which utilise quartz windows. PS10 models include a detachable beam tube to block stray light. Fibre optic connectors are available as accessories.

Model	Wavelength Range	Power Range			Max. Ave. Power Density	Max. Pulse Energy Density	Long Pulse Energy	Detector Diameter	Detector Coating
		Max	Min	Res.
PS10	0.3 - 11µm	1W	0.1mW	10µW	0.5kW/cm2	50mJ/cm2	N/A	10mm	Black
PS10Q	0.3 - 3µm	1W	0.1mW	10µW	0.5kW/cm2	50mJ/cm2	N/A	10mm	Black
PS19	0.3 - 11µm	1W	0.1mW	10µW	0.5kW/cm2	50mJ/cm2	N/A	19mm	Black
PS19Q	0.3 - 3µm	1W	0.1mW	10µW	0.5kW/cm2	50mJ/cm2	N/A	19mm	Black
PM3	0.3 - 11µm	2W	0.5mW	50µW	0.5kW/cm2	50mJ/cm2	N/A	19mm	Black
PM3Q	0.3 - 3µm	2W	0.5mW	50µW	0.5kW/cm2	50mJ/cm2	N/A	10mm	Black

Accessories for Coherent high sensitivity thermopile sensors are listed in the table below.

Part No.	Description
33-1413	Fibre optic adaptor, SMA
33-1421	Fibre optic adaptor, DIN 2106
33-1439	Fibre optic adaptor, FC/PC

Air-Cooled Thermopile Sensors (up to 150W)

The air cooled thermopile sensors are designed for use with low-to-medium powered CW and pulsed lasers from 10mW to 150W average power output. These sensors are able to dissipate the incident laser energy via convection cooling which makes them convenient to setup and use. Within this family of sensors you can select between a broadband or DUV excimer detector coating. The former offers uniform spectral response from 190nm to 11.0μm, while the excimer coating is optimised for use from 157nm to 351nm. The PM-10 and PM-30 are available with selected meters at reduced prices as part of Coherent's power meter value package programme

Model	Wavelength Range	Power Range			Max. Ave. Power Density	Max. Pulse Energy Density	Long Pulse Energy	Detector Diameter	Detector Coating
		Max	Min	Res.
PM2	0.19 - 11µm	2W	10mW	1mW	26kW/cm2	0.6J/cm2	0.5 - 2J	19mm	Broadband
PM2X	0.15 - 1µm	2W	10mW	1mW	26kW/cm2	0.6J/cm2	0.5 - 2J	19mm	Excimer
PM10	0.19 - 11µm	10W	10mW	1mW	26kW/cm2	0.6J/cm2	0.5 - 10J	19mm	Broadband
PM10X	0.15 - 1µm	10W	10mW	1mW	26kW/cm2	0.6J/cm2	0.5 - 10J	19mm	Excimer
PM30	0.19 - 11µm	30W	100mW	10mW	26kW/cm2	0.6J/cm2	0.5 - 50J	19mm	Broadband
PM30X	0.15 - 1µm	30W	100mW	10mW	26kW/cm2	0.6J/cm2	0.5 - 50J	19mm	Excimer
PM100-19C	0.19 - 11µm	100W	300mW	30mW	26kW/cm2	0.6J/cm2	1 - 100J	19mm	Broadband
PM150	0.19 - 11µm	150W	300mW	30mW	26kW/cm2	0.6J/cm2	1 - 150J	19mm	Broadband
PM150-50	0.19 - 11µm	150W	300mW	30mW	26kW/cm2	0.6J/cm2	1 - 150J	50mm	Broadband
PM150X	0.15 - 1µm	150W	300mW	30mW	26kW/cm2	0.6J/cm2	1 - 150J	50mm	Excimer

Water-Cooled Thermopile Sensors (up to 150W)

These compact, block sensors are ideal when space is an issue. They must be water-cooled to achieve the continuous, full power rating, but they can also be mounted on a heat-sink or as stand alone sensors for intermittent application of power. These models incorporate cables for attachment to our meters. OEM versions of these sensors are also offered; OEM versions include either a BNC or 4-pin connector to facilitate use in an embedded setting within a laser system.

Model	Wavelength Range	Power Range			Max. Ave. Power Density	Max. Pulse Energy Density	Long Pulse Energy	Detector Diameter	Detector Coating
		Max	Min	Res.
PM10-19C	0.19 - 11µm	10W	10mW	1mW	26kW/cm2	0.6J/cm2	0.5 - 2J	19mm	Broadband
PM150-19C	0.19 - 11µm	150W	300mW	30mW	26kW/cm2	0.6J/cm2	1 - 150J	19mm	Broadband
PM150-50C	0.19 - 11µm	150W	300mW	30mW	26kW/cm2	0.6J/cm2	1 - 150J	50mm	Broadband
PM150-50XC	0.15 - 1µm	150W	300mW	30mW	26kW/cm2	0.6J/cm2	1 - 150J	50mm	Excimer

Fan-Cooled Thermopile Sensors (up to 300W)

These fan-cooled thermopiles bridge the gap between the air-cooled and water-cooled sensors. They are an excellent choice when the use of water cooling is not desirable. A compact, wall-mount power supply provides the 12V DC required to drive the fan.

Model	Wavelength Range	Power Range			Max. Ave. Power Density	Max. Pulse Energy Density	Long Pulse Energy	Detector Diameter	Detector Coating
		Max	Min	Res.
PM200F-19	0.19 - 11µm	200W	1W	100mW	26kW/cm2	0.6J/cm2	1 - 200J	19mm	Broadband
PM200F-50	0.19 - 11µm	200W	1W	100mW	26kW/cm2	0.6J/cm2	1 - 200J	50mm	Broadband
PM200F-50X	0.15 - 1µm	200W	1W	100mW	26kW/cm2	0.6J/cm2	1 - 200J	50mm	Excimer
PM300F-19	0.19 - 11µm	300W	1W	100mW	26kW/cm2	0.6J/cm2	1 - 300J	19mm	Broadband
PM300F-50	0.19 - 11µm	300W	1W	100mW	26kW/cm2	0.6J/cm2	1 - 300J	50mm	Broadband
PM300F-50X	0.15 - 1µm	300W	1W	100mW	26kW/cm2	0.6J/cm2	1 - 300J	50mm	Excimer

High Power Water-Cooled Thermopile Sensors (up to 10kW)

Most lasers above 300W will require one of these thermopile sensors that require water cooling at all times. A post and stand are included with each sensor.

Model	Wavelength Range	Power Range			Max. Ave. Power Density	Max. Pulse Energy Density	Long Pulse Energy	Detector Diameter	Detector Coating
		Max	Min	Res.
PM300	0.19 - 11µm	300W	1W	100mW	26kW/cm2	0.6J/cm2	N/A	19mm	Broadband
PM1K	0.19 - 11µm	1kW	100W	1W	26kW/cm2	0.6J/cm2	N/A	50mm	Broadband
PM3K	0.19 - 11µm	3kW	100W	1W	26kW/cm2	0.6J/cm2	N/A	50mm	Broadband
PM5K	0.19 - 11µm	5kW	100W	1W	26kW/cm2	0.6J/cm2	N/A	50mm	Broadband
PM10K	0.19 - 11µm	10kW	100W	1W	26kW/cm2	0.6J/cm2	N/A	50mm	Broadband

Large Area High Power Water-Cooled Thermopile Sensors (up to 5kW)

These large-area thermopiles are designed to handle large laser diode arrays. The 100 mm diameter models are also useful for diode bars and large cross-section laser beams. Water-cooling is required at all times.

Model	Wavelength Range	Power Range			Max. Ave. Power Density	Max. Pulse Energy Density	Long Pulse Energy	Detector Diameter	Detector Coating
		Max	Min	Res.
PM1K-100	0.19 - 11µm	1kW	100W	1W	26kW/cm2	0.6J/cm2	N/A	100mm	Broadband
PM3K-100	0.19 - 11µm	3kW	100W	1W	26kW/cm2	0.6J/cm2	N/A	100mm	Broadband
PM5K-100	0.19 - 11µm	5kW	100W	1W	26kW/cm2	0.6J/cm2	N/A	100mm	Broadband
PM5K-200	0.19 - 11µm	5kW	100W	1W	26kW/cm2	0.6J/cm2	N/A	200mm	Broadband

Quadrant Position Sensing Air-Cooled Thermopile Sensors (up to 100W)

These air-cooled thermopile sensors can be used with the LabMax meters to display information about both the power and the position of the incident beam on the sensor disk. This allows the user to precisely align the sensor and the beam being measured. This is particularly useful for non-visible laser beams. Obtaining beam alignment and position drift information is easy; beam position stability can be tracked over time and can be displayed in both strip chart and polar graphs.

Model	Wavelength Range	Power Range			Max. Ave. Power Density	Max. Pulse Energy Density	Long Pulse Energy	Detector Diameter	Detector Coating
		Max	Min	Res.
LM-3-HTD	0.25-10.6µm	3W	10mW	1mW	6kW/cm2	0.5J/cm2	0.5-10J	19mm	HTD
LM-10-HTD	0.25-10.6µm	10W	10mW	1mW	6kW/cm2	0.5J/cm2	0.5-10J	19mm	HTD
LM-45-HTD	0.25-10.6µm	45W	100mW	10mW	6kW/cm2	0.5J/cm2	0.5-10J	19mm	HTD
LM-100-HTD	0.25-10.6µm	100W	100mW	10mW	6kW/cm2	0.5J/cm2	0.5-10J	19mm	HTD

Quadrant Position Sensing Water-Cooled Thermopile Sensors (to 5kW)

These air-cooled thermopile sensors can be used with the LabMax meters to display information about both the power and the position of the incident beam on the sensor disk. This allows the user to precisely align the sensor and the beam being measured. This is particularly useful for non-visible laser beams. Obtaining beam alignment and position drift information is easy; beam position stability can be tracked over time and can be displayed in both strip chart and polar graphs.

Model	Wavelength Range	Power Range			Max. Ave. Power Density	Max. Pulse Energy Density	Long Pulse Energy	Detector Diameter	Detector Coating
		Max	Min	Res.
LM-1000	0.25-10.6µm	1kW	100W	1W	2.5kW/cm2	0.5J/cm2	N/A	38mm	H
LM-2500	0.25-10.6µm	2.5kW	100W	1W	2.5kW/cm2	0.5J/cm2	N/A	55mm	H
LM-5000	0.25-10.6µm	5kW	100W	1W	2.5kW/cm2	0.5J/cm2	N/A	55mm	H

High Peak Power Thermopile Sensors (for Q-switched lasers)

Models PM10V1, PM30V1 and PM30V1Q are designed for use with high peak power Q-switched Nd:YAG lasers with repetition rates ranging from 5 to 50Hz. These sensors are primarily used with 1064 and 532nm, but can also be used at additional YAG harmonics down to 355 and 266 nm. The sensor disk contains a volume-absorbing substrate that allows the laser energy to be absorbed in the bulk of the material as opposed to the front surface. This results in a damage threshold approaching 5J/cm². These sensors were designed with a removable front aperture to allow easy replacement of the volume-absorbing substrate by the user, should the substrate be damaged.

Model	Wavelength Range	Power Range			Max. Ave. Power Density	Max. Pulse Energy Density	Long Pulse Energy	Detector Diameter	Detector Coating
		Max	Min	Res.
PM10V1	0.19 - 3µm	10W	10mW	1mW	50W/cm2	2J/cm2	N/A	19mm	Broadband
PM30V1	0.19 - 3µm	30W	30mW	10mW	50W/cm2	2J/cm2	N/A	19mm	Broadband
PM30V1Q	0.19 - 3µm	30W	30mW	10mW	50W/cm2	2J/cm2	N/A	19mm	Broadband