Thorlabs' Microscope Slide Peak Power Sensor is designed to measure the relative peak power of two-photon lasers. It shares the same physical dimensions as a microscope slide, enabling measurements of the relative peak power at the focus of a microscope and making the sensor ideal for laser pulse optimization for multiphoton microscopy.
- Measure Relative Peak Power of Two-Photon Lasers
- Compatible with Microscope Stages for Measurements at the Sample
- Designed to Optimize Pulses for Multiphoton Imaging
- Compatible with Dry, Water Immersion, and Oil Immersion Objectives
Features
- Designed to Measure Relative Peak Power of Two-Photon Lasers
- Nonlinear Crystal Enables Direct Measurement of the Laser's Second Harmonic
- Laser Wavelength Range: 780 - 1300 nm
- Second-Harmonic Wavelength Range: 390 - 650 nm
- Footprint Enables Peak Power Optimization at the Sample Plane
- Compatible with Dry, Water Immersion, and Oil Immersion Objectives
- Compatible with Thorlabs' Power Meter Consoles (Sold Below)
Applications
- Optimize Group Delay Dispersion of Femtosecond Lasers at the Focus of a Two-Photon Microscope
- Ensure Laser Conditions are Consistent Between Experiments
- Quickly Evaluate the Quality of Femtosecond Laser Pulses
The NS170C sensor utilizes a second-order nonlinear β-BBO (beta-BaB2O4) crystal to convert incident ultrafast near-infrared (NIR) pulses into their visible second harmonic. Because the efficiency of second harmonic generation (SHG) is proportional to the peak power density, or peak intensity, of the NIR femtosecond pulses, the magnitude of the detected second harmonic light provides a relative measurement of the peak power of the laser. Please see the Optical Design and Operation tabs for more details.
The NS170C sensor is compatible with microscope slide holders of standard upright and inverted microscopes. As illustrated in the animation to the right, the sensor can be used to measure the relative peak power at the focus of a microscope. This allows the user to optimize the laser pulse duration directly at the sample plane for high image contrast (see the Applications tab for details). The sensor is also post-mountable via an 8-32 (M4 x 0.7) tapped hole, allowing for the relative peak power to be measured in an optical set-up of standard optomechanical components.
The housing of the NS170C sensor features a knurled adjustment wheel to tune the angle between the light's polarization orientation and the β-BBO crystal's optical axis. At the entrance of the sensor is a 170 µm thick cover glass sealed to the sensor housing, allowing the sensor to be used with dry, water immersion, and oil immersion objectives. The working distance from the top of the cover glass to the β-BBO crystal is 0.22 mm. The bottom of the sensor housing features a laser-engraved alignment crosshair that marks the active sensor area to aid in aligning and focusing the beam. To use, insert the housing into the beam path such that the engraved side is facing the objective of your microscope. Once the beam is centered on the engraved target, simply turn the sensor over so that the detector is facing the beam in order to take a power measurement.
Second Harmonic Generation
The efficiency of SHG is dependent on the peak power density of incident laser pulses. Once the sensor is positioned at the focal plane of the microscope objective, the effective focal area becomes fixed and the SHG signal is only dependent on peak power. For a given average laser power and repetition rate, the peak power is only dependent on the pulse duration. Therefore, changes to the pulse duration results in a clear metered readout of the SHG power, allowing for optimization of laser pulses directly at the sample plane. Please see the Operation tab for a detailed description of how these parameters impact the SHG conversion efficiency.
Power Meter Console and Interface Compatibility
The NS170C sensor is compatible with the PM100D, PM100A, PM400, and PM5020 power meter consoles, as well as many of our C-series power and energy meter interfaces, which provide communication between the sensor and an external control unit such as a PC. A 1.5 m cable attached to the side of the sensor head leads to a D-sub 9-pin male connector. Nonvolatile memory in the sensor connector contains sensor information data and the NIST- and PTB- traceable calibration data. Please note that the NIST and PTB calibration is for the visible light incident on the detector; however, the magnitude of that visible light is specific to the illumination conditions of the NIR femtosecond pulses. Please see the Applications tab for more details.
When using the NS170C sensor with our power meter consoles and interfaces, please use the NIR input laser wavelength as the source wavelength.
Recalibration Service
Recalibration services are available for our power sensors and power meter consoles. We recommend your Thorlabs sensor and console be recalibrated as a pair; however, each may be recalibrated individually. Recalibration of a single-channel power and/or energy meter console or interface is included with the CAL-NS Microscope Slide Peak Power Sensor Recalibration Service below at no additional cost. We recommend yearly recalibration to ensure accuracy and performance.
- Microscope Slide Peak Power Sensor for Two-Photon Lasers
- Utilizes a β-BBO Crystal to Measure the Relative Peak Power of Two-Photon Lasers
- Laser Wavelength Range: 780 - 1300 nm
- Second-Harmonic Wavelength Range: 390 - 650 nm
- Ideal for Optimizing Laser Conditions at the Sample Plane of a Microscope
- Compatible with Dry, Water Immersion, and Oil Immersion Objectives
- Yearly Recalibration with CAL-NS Recalibration Service Recommended
The NS170C Microscope Slide Peak Power Sensor is designed to measure the relative peak power of lasers for multiphoton microscopy. It can be used with femtosecond lasers with center wavelengths from 780 nm to 1300 nm. To avoid damaging the optical components, the maximum average power should not exceed 350 mW. The damage threshold for the peak power density is 10 TW/cm2 at 80 MHz repetition rate and for microscope objectives with NA > 0.5; the damage threshold will be lower for NA < 0.5. The photodiode sensor can detect SHG light with wavelengths from 390 nm to 650 nm at optical powers from 10 nW to 5 mW. Please see the Specs tab for more information.
The converted SHG signal of the NS170C peak power sensor is highly dependent on the experimental conditions (see Operation tab for details). The wavelength, pulse duration, quality of the temporal pulse profile, repetition rate, and power of the NIR input laser in addition to the objective numerical aperture and immersion all contribute to the magnitude of the converted visible SHG signal. The table below describes the typical performance of the NS170C peak power sensor under various experimental conditions and can be used as a reference when evaluating the expected SHG signal for a given experiment.
Thorlabs recommends yearly recalibration of the NS170C sensor. Thorlabs offers a recalibration service for this photodiode sensor, which can be ordered below (Item # CAL-NS). 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. For more information, please contact