Item #a	S401C	S405C
Sensor Image (Click the Image to Enlarge)
Wavelength Range	190 nm - 20 µm	190 nm - 20 µm
Optical Power Range	10 µW - 1 W (3 Wb)	100 µW - 5 W
Input Aperture Size	Ø10 mm	Ø10 mm
Active Detector Area	10 mm x 10 mm	10 mm x 10 mm
Max Optical Power Density	500 W/cm² (Avg.)	1.5 kW/cm² (Avg.)
Detector Type	Thermal Surface Absorber (Thermopile) with Background Compensation	Thermal Surface Absorber (Thermopile)
Linearity	±0.5%	±0.5%
Resolutionc	1 µW	5 µW
Measurement Uncertaintyd	±3% @ 1064 nm ±5% @ 190 nm - 10.6 µm	±3% @ 1064 nm ±5% @ 250 nm - 17 µm
Response Timee	1.1 s	1.1 s
Cooling	Convection (Passive)
Housing Dimensions (Without Adapter)	33.0 m x 43.0 mm x 15.0 mm (1.30" x 1.69" x 0.59")	40.6 mm x 40.6 mm x 16.0 mm (1.60" x 1.60" x 0.63")
Temperature Sensor (In Sensor Head)	NTC Thermistor	NTC Thermistor
Cable Length	1.5 m
Post Mounting	Universal 8-32 / M4 Taps (Post Not Included)	Universal 8-32 / M4 Taps (Post Not Included)
30 mm Cage Mounting	-	Two 4-40 Tapped Holes & Two Ø6 mm Through Holes
Aperture Threads	-	Internal SM05
Accessories	Externally SM1-Threaded Adapter Light Shield with Internal SM05 Threading	Externally SM1-Threaded Adapter
Compatible Consoles	PM400, PM100D, and PM100A
Compatible Interfaces	PM101, PM101A, PM101R, PM101U, PM102, PM102A, PM102U, and PM100USB

• For complete specifications, please see the Specs tab.
• For conditions of intermittent use, with a maximum exposure time of 20 minutes for the S401C. The S405C saturates for optical input powers >5 W.
• Measurement taken with the legacy PM200 console for the S401C and the PM400 console for the S405C. In all cases, the acceleration circuit was switched off. Resolution performance will be similar with our other power meter consoles.
• Defined as the measurement uncertainty during calibration at the specified wavelengths for a beam diameter > 1 mm. The ±3% specification was determined by laser calibration, and the ±5% specification was determined through spectral calibration, in which values were interpolated using the laser calibration data and the absorption curve for the absorber. Calibration can be performed at 10.6 µm upon request.
• Typical natural response time (0 - 95%). Our power consoles can provide estimated measurements of optical power on an accelerated time scale (typically <1 s). See the Operation tab for additional information.

• - High Resolution of 1 μW or 5 μW
• - S401C and S405C Have Thermistors Used to Monitor Temperature of Sensor Head
• - S401C: Background Compensation for Low-Drift Measurements
• - S405C: Accommodates Average Optical Power Densities up to 1.5 kW/cm²

Click to Enlarge
S401C Thermal Sensor with Included Light Shield

Thorlabs offers two broadband thermal power sensors designed to measure low optical power sources with high resolution. Both thermal sensor's broadband coating has a flat spectral response over a wide wavelength range, as shown in the plot below. The aperture size of Ø10 mm allows for easy alignment and measurement of large-spot-size laser sources. For easy integration with Thorlabs' lens tube systems and SM1-threaded (1.035"-40) fiber adapters (available below), both sensors include an externally SM1-threaded adapter.

The S401C uses active thermal background compensation to provide low-drift power measurements. This is implemented through the use of two sensor circuits to measure heat flow between the light absorber and heat sink in both directions. The measurements of the two sensor circuits are then subtracted, which minimizes the effect of thermal drift on the laser power measurement. (For information about how external thermal disturbances can affect thermal power sensor readings, please see the Operation tab.) The S401C's broadband coating offers high absorption at wavelengths between 0.19 and 20 µm (shown in the graph below), which makes it ideal for use with aligning and measuring Mid-IR Quantum Cascade Lasers (QCLs). The included, internally SM05-threaded (0.535"-40) light shield is shown in the photo above.

The S405C has internal SM05 (0.535"-40) threading that is directly compatible with our SM05 lens tubes, and it can also connect directly to Thorlabs' 30 mm Cage Systems.

Thorlabs offers a recalibration service for these sensors, which can be ordered below (see Item # CAL-THPY).

Click to Enlarge
Raw Data: S401C, S405C
The S405 shares the same absorption curve with the S415C, S425C, and S245C-L. (All are sold below.)

Item #a	S415C	S425C
Sensor Image (Click Image to Enlarge)
Wavelength Range	190 nm - 20 µm	190 nm - 20 µm
Optical Power Range	2 mW - 10 W (20 Wb)	2 mW - 10 W (20 Wb)
Input Aperture Size	Ø15 mm	Ø25.4 mm
Active Detector Area	Ø15 mm	Ø27 mm
Max Optical Power Density	1.5 kW/cm² (Avg.)	1.5 kW/cm² (Avg.)
Detector Type	Thermal Surface Absorber (Thermopile)
Linearity	±0.5%	±0.5%
Resolutionc	100 µW	100 µW
Measurement Uncertaintyd	±3% @ 1064 nm ±5% @ 250 nm - 17 µm	±3% @ 1064 nm ±5% @ 250 nm - 17 µm
Response Timee	0.6 s	0.6 s
Cooling	Convection (Passive)
Housing Dimensions (Without Adapter)	50.8 mm x 50.8 mm x 35.0 mm (2.00" x 2.00" x 1.38")	50.8 mm x 50.8 mm x 35.0 mm (2.00" x 2.00" x 1.38")
Temperature Sensor (In Sensor Head)	NTC Thermistor
Cable Length	1.5 m
Post Mounting	Universal 8-32 / M4 Taps (Post Not Included)	Universal 8-32 / M4 Taps (Post Not Included)
30 mm Cage Mounting	-	-
Aperture Threads	Internal SM1	Internal SM1
Removable Heatsink	Yes	Yes
Accessories	Externally SM1-Threaded Adapter	Externally SM1-Threaded Adapter
Compatible Consoles	PM400, PM100D, and PM100A
Compatible Interfaces	PM101, PM101A, PM101R, PM101U, PM102, PM102A, PM102U, and PM100USB

• For complete specifications, please see the Specs tab.
• Two Minute Maximum Exposure Time
• Measurement taken with the PM400 with the acceleration circuit switched off. Resolution performance will be similar with our other power meter consoles.
• Defined as the measurement uncertainty during calibration at the specified wavelengths for a beam diameter > 1 mm. The ±3% specification was determined by laser calibration, and the ±5% specification was determined through spectral calibration, in which values were interpolated using the laser calibration data and the absorption curve for the absorber. Calibration can be performed at 10.6 µm upon request.
• Typical natural response time (0 - 95%). Our power consoles can provide estimated measurements of optical power on an accelerated time scale (typically <1 s). As the natural response times of the S415C and S425C are fast, these do not benefit from accelerated measurements and this function cannot be enabled. See the Operation tab for additional information.

• - 100 µW Optical Power Resolution
• - Thermistors Used to Monitor Temperature of Sensor Head
• - Removable Heat Sinks Included

These thermal power sensors are designed for general broadband power measurements of low and medium power light sources. All include an externally SM1-threaded (1.035"-40) adapter, with threading concentric with the input aperture. The adapters are useful for mounting Ø1" Lens Tubes and Fiber Adapters (available below). The apertures of the S415C and S425C have internal SM1 threading.

These sensors operate with fast (<0.6 s) natural response times, and their removable heat sinks provide a high degree of flexibility to those interested in integrating them into custom setups or replacing the included heat sink with one that is water or fan cooled. If replacing the heat sink, please note that the replacement must provide heat dissipation adequate for the application.

Thorlabs offers a recalibration service for these sensors, which can be ordered below (see Item # CAL-THPY).

Click to Enlarge
Click Here for Raw Data
The absorption curves of each of the thermal power sensors designed for use with low and medium power optical sources.

Click to Enlarge
Raw Data: S350C, S425C-L, S322C
The absorption curves of each of the thermal power sensors designed for use with low and medium power optical sources.

• - Thermistors Used to Monitor Temperature of Sensor Head
• - S322C Has 4-40 Taps for Use with Our 30 mm Cage Systems
• - S350C Has Ø40 mm Aperture Well Suited to Excimer and Other Lasers with Large Spot Sizes
• - S425C-L Features Removable Heat Sink
• - S322C is Fan Cooled with an Optical Power Range up to 200 W

These thermal power sensors are designed for general broadband power measurements of low and medium power light sources. With the exception of the S350C, all include an adapter with external SM1 (1.035"-40) threading concentric with the input aperture. This allows the sensors to be integrated into existing Ø1" lens tube systems in addition to being compatible with fiber adapters (available below). The aperture of the S425C-L has internal SM1 threading.

The S425C-L operates with a fast (<0.6 s) natural response time and has a removable heat sink, which provides a high degree of flexibility to those interested in integrating them into custom setups or replacing the included heat sink with one that is water or fan cooled. If replacing the heat sink, please note that the replacement must provide heat dissipation adequate for the application.

Thorlabs offers a recalibration service for these sensors, which can be ordered below (see Item # CAL-THPY).

Item #a	S350C	S425C-L	S322C
Sensor Image (Click Image to Enlarge)
Wavelength Range	190 nm- 1.1 µm, 10.6 µm	190 nm - 20 µm	250 nm - 11 µm
Optical Power Range	10 mW - 40 W (60 Wb)	2 mW - 50 W (75 Wb)	100 mW - 200 W (250 Wb)
Input Aperture Size	Ø40 mm	Ø25.4 mm	Ø25 mm
Active Detector Area	Ø40 mm	Ø27 mm	Ø25 mm
Max Optical Power Density	2 kW/cm² (Avg.)	1.5 kW/cm² (Avg.)	4 kW/cm² (Avg., CO2)
Detector Type	Thermal Surface Absorber (Thermopile)
Linearity	±1%	±0.5%	±1%
Resolutionc	1 mW	100 µW	5 mW
Measurement Uncertaintyd	±3% @ 351 nm ±5% @ 190 nm - 1100 nm	±3% @ 1064 nm ±5% @ 250 nm - 17 µm	±3% @ 1064 nm ±5% @ 266 nm - 1064 nm
Response Timee	9 s (1 s from 0 to 90%)	0.6 s	5 s (1 s from 0 to 90%)
Cooling	Convection (Passive)		Forced Air with Fanf
Housing Dimensions (Without Adapter, if Applicable)	100 mm x 100 mm x 54.2 mm (3.94" x 3.94" x 2.13")	100.0 mm x 100.0 mm x 58.0 mm (3.94" x 3.94" x 2.28")	100 mm x 100 mm x 86.7 mm (3.94" x 3.94" x 3.41")
Temperature Sensor (In Sensor Head)	NTC Thermistor
Cable Length	1.5 m
Post Mounting	M6 Threaded Taps, Includes Ø1/2" Post, 75 mm Long	Universal 8-32 / M4 Taps (Post Not Included)	M6 Threaded Taps, Includes Ø1/2" Post, 75 mm Long
30 mm Cage Mounting	-	-	Four 4-40 Tapped Holes
Aperture Threads	-	Internal SM1	-
Removable Heatsink	-	Yes	-
Accessories	-	Externally SM1-Threaded Adapter	Externally SM1-Threaded Adapter
Compatible Consoles	PM400, PM100D, and PM100A
Compatible Interfaces	PM101, PM101A, PM101R, PM101U, PM102, PM102A, PM102U, and PM100USB

• For complete specifications, please see the Specs tab.
• Two Minute Maximum Exposure Time
• Measurement taken with the PM100D console, except for the S425C-L in which the PM400 was used. In all cases, the acceleration circuit was switched off. Resolution performance will be similar with our other power meter consoles.
• Defined as the measurement uncertainty during calibration at the specified wavelengths for a beam diameter > 1 mm. The ±3% specification was determined by laser calibration, and the ±5% specification was determined through spectral calibration, in which values were interpolated using the laser calibration data and the absorption curve for the absorber. Calibration can be performed at 10.6 µm upon request.
• Typical natural response time (0 - 95%). Our power consoles can provide estimated measurements of optical power on an accelerated time scale (typically <1 s) for the S350C and S322C. As the natural response time of the S425C-L is fast, the S425C-L does not benefit from acceleration and this function cannot be enabled. See the Operation tab for additional information.
• 12 VDC power supply is included.

Item #a	S370C	S470C
Sensor Image (Click Image to Enlarge)
Wavelength Range	400 nm - 5.2 µm	250 nm - 10.6 µm
Optical Power Range	10 mW - 10 W (15 Wb)	100 µW - 5 W (Pulsed and CW)
Input Aperture Size	Ø25 mm	Ø15 mm
Active Detector Area	Ø25 mm	Ø16 mm
Max Optical Power Density	35 W/cm² (Avg.); 100 GW/cm² (Peak)
Detector Type	Thermal Volume Absorber (Thermopile)
Linearity	±1%	±0.5%
Resolutionc	250 µW	10 µW
Measurement Uncertaintyd	±3% @ 1064 nm ±5% @ 400 nm - 1064 nm	±3% @ 1064 nm ±5% @ 250 nm - 10.6 µm
Response Timee	45 s (3 s from 0 to 90%)	6.5 s (<2 s from 0 to 90%)
Cooling	Convection (Passive)
Housing Dimensions (Without Adapter, if Applicable)	75 mm x 75 mm x 51.2 mm (2.95" x 2.95" x 2.02")	45.0 mm x 45.0 mm x 18.0 mm (1.77" x 1.77" x 0.71")
Temperature Sensor (In Sensor Head)	N/A	N/A
Cable Length	1.5 m
Post Mounting	M6 Threaded Taps, Includes Ø1/2" Post, 75 mm Long	Universal 8-32 / M4 Tap (Post Not Included)
30 mm Cage Mounting	Four 4-40 Tapped Holes	-
Aperture Threads	-	External SM1
Accessories	Externally SM1-Threaded Adapter	-
Compatible Consoles	PM400, PM100D, and PM100A
Compatible Interfaces	PM101, PM101A, PM101R, PM101U, PM102, PM102A, PM102U, and PM100USB

• For complete specifications, please see the Specs tab.
• Two Minute Maximum Exposure Time
• Measurement taken with the PM100D console for the S370C and with the legacy PM200 for the S470C. In all cases, the acceleration circuit was switched off. Resolution performance will be similar with our other power meter consoles.
• Defined as the measurement uncertainty during calibration at the specified wavelengths for a beam diameter > 1 mm. The ±3% specification was determined by laser calibration, and the ±5% specification was determined through spectral calibration, in which values were interpolated using the laser calibration data and the absorption curve for the absorber. Calibration can be performed at 10.6 µm upon request.
• Typical natural response time (0 - 95%). Our power consoles can provide estimated measurements of optical power on an accelerated time scale (typically <2 s). See the Operation tab for additional information.

• - Designed for Optical Power Measurements of Nd:YAG Lasers
• - Ideal for Applications with High Peak Pulse Powers
• - S370C: Ø25 mm Aperture for Large-Spot-Size Beams
• - S470C: High-Sensitivity for High-Peak-Power Pulses with Low Average Power

The S370C and S470C Thermal Sensors are designed to measure short and highly energetic laser pulses. All of these units are post-mountable for free-space applications and feature NIST-traceable data stored in the sensor connector.

These thermal power sensors are unique in that they have thermal volume absorbers, where our other thermal power sensors have thermal surface absorbers. The volume absorber consists of a Schott glass filter. Incident pulses are absorbed and the heat is distributed throughout the volume. In this way, pulses that would have damaged the absorption coating of a thermal surface absorber are safely measured by these thermal volume absorbers.

The S370C features a large Ø25 mm aperture ideal for large-spot-size beams, and it is compatible with average powers from 10 mW to 10 W (CW).

In comparison, the S470C is faster, as the glass absorber volume is reduced and other design parameters have been optimized for speed. This results in a different optical power range, with the ability to measure powers down to 100 µW. The Ø15 mm aperture is of the S470C is smaller, and it has a lower max average power of 5 W. Its 10 µW resolution is better than the 250 µW resolution of the S370C.

For high-power, pulsed-lasers the S370C and S470C Thermal Sensors can withstand high average and peak power densities. However, for sensors with a broader spectral range or shorter response time, consider one of our  Pyroelectric Energy Sensors.

Thorlabs offers a recalibration service for these sensors, which can be ordered below (see Item # CAL-THPY).

Click to Enlarge
Click Here for Raw Data
This absorption curve is shown over a broader wavelength range than the sensors' operating ranges. See the table for the operating wavelength range of each sensor.

These internally SM1-threaded (1.035"-40) adapters mate terminated fiber to any of our externally SM1-threaded components, including a selection of our photodiode power sensors, our thermal power sensors, and our photodetectors.

The APC adapters have two dimples in the front surface that allow them to be tightened with the SPW909 or SPW801 spanner wrench. The dimples do not go all the way through the disk so that the adapter can be used in light-tight applications when paired with SM1 lens tubes.

For details on narrow versus wide key connectors, please see our Intro to Fiber tutorial. Please contact Tech Support if you are unsure if the adapter is mechanically compatible.

Item #	S120-FC2	S120-FC	S120-APC2a	S120-APCa	S120-SMA	S120-ST	S120-SC	S120-LC
Adapter Image (Click the Image to Enlarge)
Fiber Connector Type	FC/PC, 2.0 mm Narrow Key	FC/PC, 2.2 mm Wide Key	FC/APC, 2.0 mm Narrow Key	FC/APC 2.2 mm Wide Key	SMA	ST/PC	SC/PCb	LC/PC
Thread	Internal SM1 (1.035"-40)

• The S120-APC and S120-APC2 are designed with a 4° mechanical angle to compensate for the refraction angle of the output beam.
• In certain angle-independent applications, this adapter may also be used with SC/APC connectors

Thorlabs offers recalibration services for our Thermal Power and Pyroelectric Energy Sensors. To ensure accurate measurements, we recommend recalibrating the sensors annually. Recalibration of a single-channel power and/or energy meter console or interface is included with the recalibration of a sensor at no additional cost.

Please note that the CAL-THPY recalibration service cannot be used for our Thermal Position & Power Sensors; recalibration for these sensors can be requested by contacting Tech Support.

The table to the upper right lists the sensors for which the CAL-THPY recalibration service is available. Please enter the Part # and Serial # of the sensor that requires recalibration prior to selecting Add to Cart.