Thorlabs offers a wide selection of power and energy meter consoles and interfaces for operating our power and energy sensors. Key specifications of all of our power meter consoles and interfaces are presented below to help you decide which device is best for your application. We also offer self-contained wireless power meters and compact USB power meters.

When used with our C-series sensors, Thorlabs' power meter consoles and interfaces recognize the type of connected sensor and measure the current or voltage as appropriate. Our C-series sensors have responsivity calibration data stored in their connectors. The console will read out the responsivity value for the user-entered wavelength and calculate a power or energy reading.

• Photodiode sensors deliver a current that depends on the input optical power and the wavelength. The current is fed into a transimpedance amplifier, which outputs a voltage proportional to the input current. The photodiode's responsivity is wavelength dependent, so the correct wavelength must be entered into the console for an accurate power reading. The console reads out the responsivity for this wavelength from the connected sensor and calculates the optical power from the measured photocurrent.
• Thermal sensors deliver a voltage proportional to the input optical power. Based on the measured sensor output voltage and the sensor's responsivity, the console will calculate the incident optical power.
• Energy sensors are based on the pyroelectric effect. They deliver a voltage peak proportional to the pulse energy. If an energy sensor is recognized, the console will use a peak voltage detector and the pulse energy will be calculated from the sensor's responsivity.

The consoles and interfaces are also capable of providing a readout of the current or voltage delivered by the sensor. Select models also feature an analog output.

Consoles

Item #	PM100A	PM100D	PM400	PM320E
(Click Photo to Enlarge)
Key Features	Analog Power Measurements	Digital Power and Energy Measurements	Digital Power and Energy Measurements, Touchscreen Control	Dual Channel
Compatible Sensors	Photodiode and Thermal Power	Photodiode and Thermal Power; Pyroelectric
Housing Dimensions (H x W x D)	7.24" x 4.29" x 1.61" (184 mm x 109 mm x 41 mm)	7.09" x 4.13" x 1.50" (180 mm x 105 mm x 38 mm)	5.35" x 3.78" x 1.16" (136.0 mm x 96.0 mm x 29.5 mm)	4.8" x 8.7" x 12.8" (122 mm x 220 mm x 325 mm)
Channels	1			2
External Temperature Sensor Input (Sensor not Included)	-	-	Instantaneous Readout and Record Temperature Over Time	-
External Humidity Sensor Input (Sensor not Included)	-	-	Instantaneous Readout and Record Humidity Over Time	-
GPIO Ports	-		4, Programmable	-
Source Spectral Correction	-	-		-
Attenuation Correction	-	-		-
External Trigger Input	-	-	-
Display
Type	Mechanical Needle and LCD Display with Digital Readout	320 x 240 Pixel Backlit Graphical LCD Display	Protected Capacitive Touchscreen with Color Display	240 x 128 Pixels Graphical LCD Display
Dimensions	Digital: 1.9" x 0.5" (48.2 mm x 13.2 mm) Analog: 3.54" x 1.65" (90.0 mm x 42.0 mm)	3.17" x 2.36" (81.4 mm x 61.0 mm)	3.7" x 2.1" (95 mm x 54 mm)	3.7" x 2.4" (94.0 mm x 61.0 mm)
Refresh Rate	20 Hz		10 Hz (Numerical) 25 Hz (Analog Simulation)	20 Hz
Measurement Viewsa
Numerical
Mechanical Analog Needle		-	-	-
Simulated Analog Needle	-
Bar Graph	-
Trend Graph	-
Histogram	-		-
Statistics
Memory
Type	-	SD Card	NAND Flash	-
Size	-	2 GB	4 GB	-
Power
Battery	LiPo 3.7 V 1300 mAh		LiPo 3.7 V 2600 mAh	-
External	5 VDC via USB or Included AC Adapter		5 VDC via USB	Selectable Line Voltage: 100 V, 115 V, 230 V (±10%)

• These are the measurement views built into the unit. All of our power meter consoles except the PM320E can be controlled using the Optical Power Monitor software package. The PM320E has its own software package.

Interfaces

Item #	PM101	PM102	PM101A	PM102A	PM101R	PM101U	PM102U	PM100USB
(Click Photo to Enlarge)
Key Features	USB, RS232, UART, and Analog Operation		USB and Analog SMA Operation		USB and RS232 Operation	USB Operation		USB Operation
Compatible Sensors	PM101 Series: Photodiode and Thermal Power PM102 Series: Thermal Power and Thermal Position & Power							Photodiode and Thermal Power; Pyroelectric
Housing Dimensions (H x W x D)	3.80" x 2.25" x 1.00" (96.5 x 57.2 x 25.4 mm)		3.94" x 2.25" x 1.00" (100.0 x 57.2 x 25.4 mm)		3.78" x 2.25" x 1.00" (95.9 x 57.2 x 25.4 mm)	3.68" x 2.25" x 1.00" (93.6 x 57.2 x 25.4 mm)		3.67" x 2.38 " x 1.13" (93.1 x 60.4 x 28.7 mm)
Channels	1
External Temperature Sensor Input (Sensor Not Included)	NTC Thermistor		-
External Humidity Sensor Input (Sensor not Included)	-
GPIO Ports	-
Source Spectral Correction	-
Attenuation Correction	-
External Trigger Input	-
Display
Type	No Built-In Display; Controlled via GUI for PC
Refresh Rate	Up to 1000 Hza							Up to 300 Hza
Measurement Viewsb
Numerical	Requires PCb
Mechanical Analog Needle	-
Simulated Analog Needle	Requires PCb
Bar Graph	Requires PCb
Trend Graph	Requires PCb
Histogram	Requires PCb
Statistics	Requires PCb
Memory
Type	Internal Non-Volatile Memory for All Settings							-
Size	-
Power
Battery	-
External	5 VDC via USB or 5 to 36 VDC via DA-15		5 VDC via USB

• Dependent on PC Settings
• These power meter interfaces do not have a built-in monitor, so all data must be displayed through a PC running the Optical Power Meter Software.

Pulsed Laser Emission: Power and Energy Calculations

Click above to download the full report.

Determining whether emission from a pulsed laser is compatible with a device or application can require referencing parameters that are not supplied by the laser's manufacturer. When this is the case, the necessary parameters can typically be calculated from the available information. Calculating peak pulse power, average power, pulse energy, and related parameters can be necessary to achieve desired outcomes including:

• Protecting biological samples from harm.
• Measuring the pulsed laser emission without damaging photodetectors and other sensors.
• Exciting fluorescence and non-linear effects in materials.

Pulsed laser radiation parameters are illustrated in Figure 1 and described in the table. For quick reference, a list of equations are provided below. The document available for download provides this information, as well as an introduction to pulsed laser emission, an overview of relationships among the different parameters, and guidance for applying the calculations. 

Equations:
Period and repetition rate are reciprocal:			and
Pulse energy calculated from average power:
Average power calculated from pulse energy:
Peak pulse power estimated from pulse energy:
Peak power and average power calculated from each other:
		and
Peak power calculated from average power and duty cycle*:
		*Duty cycle () is the fraction of time during which there is laser pulse emission.

Click to Enlarge

Figure 1: Parameters used to describe pulsed laser emission are indicated in the plot (above) and described in the table (below). Pulse energy (E) is the shaded area under the pulse curve. Pulse energy is, equivalently, the area of the diagonally hashed region. 

Parameter	Symbol	Units	Description
Pulse Energy	E	Joules [J]		A measure of one pulse's total emission, which is the only light emitted by the laser over the entire period. The pulse energy equals the shaded area, which is equivalent to the area covered by diagonal hash marks.
Period	Δt	Seconds [s]		The amount of time between the start of one pulse and the start of the next.
Average Power	Pavg	Watts [W]		The height on the optical power axis, if the energy emitted by the pulse were uniformly spread over the entire period.
Instantaneous Power	P	Watts [W]		The optical power at a single, specific point in time.
Peak Power	Ppeak	Watts [W]		The maximum instantaneous optical power output by the laser.
Pulse Width		Seconds [s]		A measure of the time between the beginning and end of the pulse, typically based on the full width half maximum (FWHM) of the pulse shape. Also called pulse duration.
Repetition Rate	frep	Hertz [Hz]		The frequency with which pulses are emitted. Equal to the reciprocal of the period.

Click to Enlarge
The PM160 wireless power meter, shown here with an iPad mini (not included), can be remotely operated using Apple mobile devices.

This tab outlines the full selection of Thorlabs' power and energy sensors. Refer to the lower right table for power meter console and interface compatibility information.

In addition to the power and energy sensors listed below, Thorlabs also offers all-in-one, wireless, handheld power meters and compact USB power meter interfaces that contain either a photodiode or a thermal sensor, as well as power meter bundles that include a console, sensor head, and post mounting accessories.

Thorlabs offers four types of sensors:

• Photodiode Sensors: These sensors are designed for power measurements of monochromatic or near-monochromatic sources, as they have a wavelength dependent responsivity. These sensors deliver a current that depends on the input optical power and the wavelength. The current is fed into a transimpedance amplifier, which outputs a voltage proportional to the input current.
• Thermal Sensors: Constructed from material with a relatively flat response function across a wide range of wavelengths, these thermopile sensors are suitable for power measurements of broadband sources such as LEDs and SLDs. Thermal sensors deliver a voltage proportional to the input optical power.
• Thermal Position & Power Sensors: These sensors incorporate four thermopiles arranged as quadrants of a square. By comparing the voltage output from each quadrant, the unit calculates the beam's position.
• Pyroelectric Energy Sensors: Our pyroelectric sensors produce an output voltage through the pyroelectric effect and are suitable for measuring pulsed sources, with a repetition rate limited by the time constant of the detector. These sensors will output a peak voltage proportional to the incident pulse energy.

Console Compatibility
Console Item #	PM100A	PM100D	PM400	PM320E	PM101 Series	PM102 Series	PM100USB
Photodiode Power						-
Thermal Power
Thermal Position	-	-		-	-		-
Pyroelectric Energy	-				-	-

Power and Energy Sensor Selection Guide

There are two options for comparing the specifications of our Power and Energy Sensors. The expandable table below sorts our sensors by type (e.g., photodiode, thermal, or pyroelectric) and provides key specifications.

Alternatively, the selection guide graphic further below arranges our entire selection of photodiode and thermal power sensors by wavelength (left) or optical power range (right). Each box contains the item # and specified range of the sensor. These graphs allow for easy identification of the sensor heads available for a specific wavelength or power range.

Sensor Type	Applications	Item #	Wavelength	Energy or Power Range	Detector Type	Aperture	Response Time
Standard Sensors	General Purpose Power Measurements	S120VC	200 - 1100 nm	50 nW - 50 mW	Si	Ø9.5 mm	<1 µsa
		S120C	400 - 1100 nm	50 nW - 50 mW		Ø9.5 mm
		S121C	400 - 1100 nm	500 nW - 500 mW		Ø9.5 mm
		S122C	700 - 1800 nm	50 nW - 40 mW	Ge	Ø9.5 mm
Slim Sensors	Power Measurements in Tight Spaces	S130VC	200 - 1100 nm	Dual Range: 5 nW - 5 mW or 50 nW - 50 mW	Si Slim	Ø9.5 mm
		S130C	400 - 1100 nm	Dual Range: 500 pW - 5 mW or 100 µW - 500 mW		Ø9.5 mm
		S132C	700 - 1800 nm	Dual Range: 5 nW - 5 mW or 100 µW - 500 mW	Gi Slim	Ø9.5 mm
Microscope Slide Sensor	Measure Power at the Sample Plane of a Microscope	S170C	350 - 1100 nm	10 nW - 150 mW	Si Large Area	18 mm x 18 mm
Integrating Sphere Sensors	Power Measurements for High Powers and Divergent Beams	S140C	350 - 1100 nm	1 µW - 500 mW	Si Integrating	Ø5 mm
		S142C	350 - 1100 nm	5 µW - 5 W		Ø12 mm
		S144C	800 - 1700 nm	100 nW - 500 mW	InGaAs Integrating	Ø5 mm
		S145C	800 - 1700 nm	1 µW - 3 W		Ø12 mm
		S146C	900 - 1650 nm	10 µW - 20 W		Ø12 mm
		S148C	1200 - 2500 nm	1 µW - 1 W		Ø5 mm
		S180C	2900 - 5500 nm	1 µW - 3 W	MCT (HgCdTe)	Ø7 mm
Fiber Sensors	Fiber Power Measurements and Field Applications	S150C	350 - 1100 nm	100 pW - 5 mW	Si Fiber	Ø5 mm
		S151C	400 - 1100 nm	1 nW - 20 mW		Ø5 mm
		S154C	800 - 1700 nm	100 pW - 3 mW	InGaAs Fiber	Ø5 mm
		S155C	800 - 1700 nm	1 nW - 20 mW		Ø5 mm

Sensor Type	Applications	Item #	Wavelength	Energy or Power Range	Detector Type	Aperture	Response Timeb
High Resolution	Broadband Measurements of Optical Powers ≤5 W with 1 µW or 5 µW Resolution	S401C	190 nm - 20 µm	10 µW - 1 W (3 Wc)	Thermal Surface Absorber with Background Compensation	Ø10 mm	1.1 s
		S405C	190 nm - 20 µm	100 µW - 5 W	Thermal Surface Absorber	Ø10 mm	1.1 s
Max Power: 10 W	General Broadband Power Measurements of Low and Medium Power Light Sources	S415C	190 nm - 20 µm	2 mW - 10 W (20 Wc)		Ø15 mm	0.6 s
		S425C	190 nm - 20 µm	2 mW - 10 W (20 Wc)		Ø25.4 mm	0.6 s
Max Power: 40 W to 200 W		S350C	190 nm - 1.1 µm, 10.6 µm	10 mW - 40 W (60 Wc)		Ø40 mm	9 s (1 s from 0 to 90%)
		S425C-L	190 nm - 20 µm	2 mW - 50 W (75 Wc)		Ø25.4 mm	0.6 s
		S322C	250 nm - 11 µm	100 mW - 200 W (250 Wc)		Ø25 mm	5 s (1 s from 0 to 90%)
High Max Power Density	Optical Power Measurements of Nd:YAG and Other Pulsed Laser Sources	S370C	400 nm - 5200 nm	10 mW - 10 W (15 Wc)	Thermal Volume Absorber	Ø25 mm	45 s (3 s from 0 to 90%)
		S470C	250 nm - 10.6 µm	100 µW - 5 W		Ø15 mm	6.5 s (<2 s from 0 to 90%)
Microscope Slide	Measure Power at the Sample Plane of a Microscope	S175C	300 nm - 10.6 µm	100 µW - 2 W	Thermal Surface Absorber	18 mm x 18 mm	3 s (<2 s from 0 to 90%)

Sensor Type	Applications	Item #	Wavelength	Power Range	Detector Type	Aperture	Response Timeb
High Resolution	Precise Beam Position and Power Measurements of Low and Medium Power Lasers	S440C	190 nm - 20 µm	0.5 mW - 5 W	Thermal Absorber, Four Quadrants	17 x 17 mm	<1.1 s
High Power		S442C	190 nm - 20 µm	10 mW - 50 W	Thermal Absorber, Four Quadrants	Ø17.5 mm	<0.6 s

Sensor Type	Applications	Item #	Wavelength	Energy or Power Range	Detector Type	Aperture	Response Time
Standard Energy Sensors	General Purpose Energy Meter	ES111C	185 nm - 25.0 µm	10 µJ - 150 mJ	Pyroelectric	Ø11 mm	N/Ad
		ES120C	185 nm - 25.0 µm	100 µJ - 500 mJ		Ø20 mm
		ES145C	185 nm - 25.0 µm	500 µJ - 2 J		Ø45 mm
High Energy Sensors	High Energy Measurements for High Peak Energy Lasers: Excimer, CO2-TEA, and Nd:YAG	ES220C	185 nm - 25.0 µm	500 µJ - 3 J	Pyroelectric Ceramic Coating	Ø20 mm
		ES245C	185 nm - 25.0 µm	1 mJ - 15 J		Ø45 mm

• The response time of the photodiode sensor. The actual response time of a power meter using these sensors will be limited by the update rate of your power meter console.
• Typical natural response time (0 - 95%). Our power consoles can provide estimated measurements of optical power on an accelerated time scale (typically <1 s) when the natual response time is approximately 1 s or greater. As the natural response times of the S415C, S425C, and S425C-L are fast, these do not benefit from accelerated measurements and this function cannot be enabled. For more information, see the Operation tab here.
• With intermittent use: maximum exposure time of 20 minutes for the S401C, otherwise maximum exposure time is 2 minutes.
• All pyroelectric sensors have a 20 ms thermal time constant, τ. This value indicates how long it takes the sensor to recover from a single pulse. To detect the correct energy levels, pulses must be shorter than 0.1τ and the repetition rate of your source must be well below 1/τ.

Sensor Options
(Arranged by Wavelength Range)

Sensor Options
(Arranged by Power Range)