Thermal Sensors

Coherent Thermal Laser Power Meter Sensors

Ideal for CW laser power, average power in pulsed lasers or the total energy from a long pulse

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). Use the links below to jump to the relevant section on this page.

Quicklinks to the available thermal sensor types:

Air-Cooled

Water-Cooled

Quadrant
(Position Sensing)

» High sensitivity
thermopile sensors

» Water-cooled thermopile sensors (to 150W)

» Quadrant, position sensing, air-cooled thermopile sensors (to 100W)

» Air-cooled thermopile sensors (to 150W)

» High power water-cooled thermopile sensors
(to 10kW)

» Quadrant, position sensing, water-cooled thermopile sensors (to 5kW)

» Fan-cooled thermopile sensors (to 300W)

»  Large area, high power water-cooled thermopile sensors (to 5kW)

 

» High peak power thermopile sensors
for Q-switched lasers

 

  

The Technology of Thermopile Sensors

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.

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

» Download Thermopile Sensor Spectral Absorption Chart

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 sych lasers. For lasers which emit a single, long pulse, thermal sensors can be used to measure the energy from the pulse in Joules. Our technical briefing explains more.

» Download Single Pulse Energy Measurements with a Thermopile Sensor Technical Briefing

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 utilize 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

Resolution

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

» Download Datasheet

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 (to 150W)

These air-cooled thermopiles represent our core power sensors. The 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 use and setup is fast. 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.

Model

Wavelength
Range

Power Range

Max. Ave.
Power Density

Max. Pulse
Energy Density

Long Pulse
Energy

Detector
Diameter

Detector
Coating

Max

Min

Resolution

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

The PM-10 and PM-30 are available with selected meters at reduced prices as part of Coherent's power meter value package programme.

» Download Datasheet

Water-Cooled Thermopile Sensors (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

Resolution

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

» Download Datasheet

Fan-Cooled Thermopile Sensors (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

Resolution

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

» Download Datasheet

High Power Water-Cooled Thermopile Sensors (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

Resolution

 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

» Download Datasheet

Large Area High Power Water-Cooled Thermopile Sensors (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

Resolution

 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

» Download Datasheet

Quadrant Position Sensing Air-Cooled Thermopile Sensors (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

Resolution

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

» Download Datasheet

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

Resolution

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

» Download Datasheet

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

Resolution

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

» Download Datasheet