Photodiode Power Sensors


Photodiode Power Sensors (C-Series)

  • Power range Covering 100 pW to 20 W
  • Wavelength Range Covering 200 nm to 1.8 µm
  • New red C-Series Connector for Quick Exchange


  • Fast Response Time and High Resolution
  • C-Series Connector Design for Quick Sensor Connection
  • Overtemp-Alert Sensor (Except S130 Series and S170C Microscope Slide Sensor)
  • Individually Calibrated with NIST- and PTB-Traceable Certificate of Calibration Plus Embedded Calibration Curve and Sensor Settings

Thorlabs' C-Series Photodiode Power Meter Sensors cover a wide power and wavelength range. These sensors are offered in standard, slim, microscope slide, integrating sphere, and compact fiber versions to meet your specific application requirements. They are the best sensor choice when a fast response time or high resolution is required and there is not a need for a flat spectral response.

These photodiode power meter sensors feature enhanced shielding to avoid electromagnetic interference as well as an over-temperature alert sensor to warn against damage and measurement errors due to overheating of the sensor (except the S130C Series Slim Sensors and the S170C Microscope Slide Sensor). For all sensors (except the S130C Slim Sensors and the S170C Miscroscope Slide Sensor), a set of fiber adapters is available to connect them to standard optical fiber patch cords (see below). Other fiber adapter types are available upon request.

The sensors have 8-32 or M4 mounting holes for mounting to 1/2" Posts. Posts and post holders are not included and sold separately.

The Photodiode Sensors presented here are compatible with C-Series power meter consoles including the the PM200, PM100D, PM100A, PM320E, and PM100USB (see the Power Meter Compatibility Chart). The S150C Series Fiber Sensors are integrated into the connector itself and directly plugged into the console.

Each sensor head is individually calibrated and is shipped with a NIST and PTB Traceable Calibration Certificate. The calibration and identification data is stored in the connector of the sensor and is downloaded automatically to the connected power meter console.

Thorlabs offers specific recalibration services for all our photodiode power sensors. To ensure accurate measurements, we recommend recalibrating the sensors annually. Please contact our tech support team for recalibration information and pricing. We also offer expedited sensor calibration.

Sensor Upgrade Service
All C-Series Sensors are incompatible with old power meter consoles with non-C-Series connectors. We offer a sensor upgrade service if you want to use your existing sensors with a new power meter console with C-Series connector. Note: upgraded sensors will be incompatible with old power meter consoles with non-C-Series connectors.


Standard Photodiode Power Sensors


  • For General Purpose Optical Power Measurements
  • Integrated Viewing Target for Easy Sensor Alignment
  • Ø9.5 mm Sensor Aperture
  • Compaptible Fiber Adapters: S120-xx Series
  • Compatible with the PM200, PM100D, PM100USB, PM100A, and PM320E Consoles
  • Sensor, Protective Cap, IR Target, and Thread Adapter Included


The S12xC Standard Photodiode Power Sensors are ideal for metering low power coherent and incoherent sources from the UV to the NIR. The NIST-Traceable, calibrated sensors feature an integrated viewing target for easy alignment, enhanced shielding against electromagnetic interference, over termperature alert device, and large Ø9.5 mm sensor aperture. The sensors are compatible with 30 mm cage systems, Ø1/2" posts, and SM1 (1.035"-40) lens tubes, and are ideal for free-space and fiber-coupled sources.


Slim Photodiode Power Sensors

  • For Optical Power Measurements in Confined Spaces
  • Very Slim Design: 5 mm Thin on Sensor Side
  • Ø9.5 mm Sensor Aperture
  • Slideable ND Filter Automatically Changes Sensor Power Range
  • Compatible with the PM200, PM100D, PM100USB, PM100A, and PM320E Consoles
  • Optional Adapter with UV/IR Target and Outer SM1 Threading


The S13xC Slim Photodiode Power Sensors are designed to take optical source power measurements in locations where space and accessibility are at a premium. The 5 mm thin Slim Photodiode Sensors can fit between closely space optics, cage systems, and other arrangements where standard power meters may not fit. The NIST-Traceable, calibrated sensors also feature a large Ø9.5 mm sensor aperture and slideable neutral density filter for dual power ranges in one compact device.


A separately available SM1A29 adapter can be attached by 2 setscrews to any S130 series power sensor to mount fiber adapters, light shields, filters or any other SM1-threaded (1.035"-40) mechanics or optics.


Microscope Photodiode Power Sensor


  • Wavelength Range: 350 nm to 1100 nm
  • Sensitive to Optical Powers from 10 nW to 150 mW
  • Designed to Measure Light on the Objective Plane of a Microscope
  • Silicon Photodiode with Large 18 mm x 18 mm Active Area
  • Sensor Housing Dimensions: 76.0 mm x 25.2 x 5.0 mm
  • Index Matching Gel Utilized in Design to Prevent Internal Reflections
  • Information Stored in Connector
    • Sensor Data
    • NIST- and PTB-Traceable Calibration Data
  • Post Mountable via 8-32 (M4) Tap


The S170C Microscope Slide Power Sensor Head is a silicon photodiode sensor designed to measure the power at the sample in microscopy setups. The silicon photodiode can detect wavelengths between 350 nm and 1100 nm at optical powers between 10 nW and 150 mW. The sensor head's 76.0 mm x 25.2 mm footprint matches that of a standard microscope slide and is compatible with most standard upright and inverted microscopes.


The photodiode has an 18 mm x 18 mm active area and is contained in a sealed housing behind a neutral density (ND) filter with OD 1.5. A 20 mm x 20 mm indentation around the surface of the ND filter is sized to accept standard microscope cover slips. An immersion medium (water, glycerol, oil) may be placed in this well directly over the ND filter, or a cover slip may be inserted first to simplify clean up. The gap between the photodiode and the neutral density filter has been filled with an index matching gel in order to prevent internal reflections from causing significant measurement errors when using high NA objectives with oil or water.


The bottom of the sensor housing features a laser-engraved grid to aid in aligning and focusing the beam. In standard microscopes, the grid can be used for beam alignment before flipping the sensor head to face the objective for power measurements. In inverted microscopes, turn on the transmitted illuminator to align the grid on the detector housing with the beam, thereby centering the sensor in front of the objective. Alternatively, the diffusive surface of the ND filter can be used as a focusing plane.


Sensor specifications and the NIST- and PTB-traceable calibration data are stored in non-volatile memory in the sensor connector and can be read out by the latest generation of Thorlabs power meters. The S170C power sensor is compatible with the PM100D, PM100A, PM100USB, PM200, and PM320E power meters. We reccomend yearly recalibration to ensure accuracy and performance. Calibration may be ordered using the CAL1 recalibration service available below.


Integrating Sphere Photodiode Power Sensors


  • For Beam Shape and Entrance Angle Independent Power Measurements
  • Integrating Sphere Design Acts as a Diffuser with Minimal Power Loss
  • Ø5 mm or Ø12 mm Input Apertures
  • Removable S120-FC Fiber Adapters (FC/PC and FC/APC) Included
  • Compaptible Fiber Adapters: S120-xx Series and S140-BFA Bare Fiber Adapter
  • Compatible with the PM200, PM100D, PM100USB, PM100A, and PM320E Consoles


The S14xC Integrating Sphere Photodiode Power Sensors are the choice for non-uniform, diverging, beam shape and entrance angle independent power measurements. Integrating spheres are ideal for power measurements from fiber sources, as well as off-axis free space sources. The integrating spheres feature large Ø5 mm or Ø12 mm apertures, SM1(1.035"-40") threaded front connections, enhanced shielding against electromagnetic interference, and an overtemp alert sensor. NIST-traceable data is stored in the sensor connector.


Fiber Photodiode Power Sensors


  • For Fiber-Based Optical Power Measurements
  • Compact Sensor Integrated into the Connector
  • Integrated Design for use in the Field and Lab
  • Includes PM20-FC Fiber Adapter
    • S150C and S151C Sensors also Include PM20-SMA Adapters
  • Compatible with all PM20-xx Series Fiber Adapters
  • Compatible with the PM200, PM100D, PM100USB, PM100A, and PM320E Consoles


The S15xC Compact Fiber Photodiode Power Sensor is designed to take power measurements from a wide variety of fiber coupled sources. The compact sensor, integrated into the power meter connector, features a unique integrated design housing the photodiode sensor, fiber coupling, and NIST-traceable data. Standard FC (and SMA - S150C and S151C) connectors are easily interchanged with a variety of standard fiber connectors.


Bare Fiber Adapter

  • Power Measurements of Bare Fiber Outputs
  • Easy Loading and Positioning of Optical Fiber in V-Groove
  • Supports Fiber with Buffer Diameters from 250 to 450 µm
  • Tight Holding without Fiber Damage by Magnet-Clip
  • Attached by 2 M2.5x5 Counter Sunk Screws
  • Compatible with S140C Series Power Sensors


Internally SM1-Threaded Fiber Adapters


These internally SM1-threaded (1.035"-40) adapters mate connectorized fiber to many of our free-space detectors and power sensors, including, but not limited to:

  • S120C and S140C Series Photodiode Power Sensors
  • S300C Series Thermal Power Sensors (Except S350C and S370C)
  • APD120A Series Photodetectors


Internally SM05-Threaded Fiber Adapters


These internally SM05-threaded (0.535"-40) adapters mate connectorized fiber to our free-space detectors and power sensors, including, but not limited to:

  • S150C Series Fiber Power Meter Sensors
  • PM200 Series Fiber Power Meter


Our Mission is to accelerate the advancement of optical technology for precision measurements and their applications from the table tops of research laboratories to standard use in communication and high technology industries. Our aim is to serve our customers. Our hope is to create a place for highly skilled people in an open environment

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