RM9 with Chopper | Laser Thermal Power Sensors | Power Sensors - Ophir

RM9 with Chopper


The RM9 radiometer system is a sensor and optical beam chopper combination for measuring the power of very low level CW or quasi CW light sources. The RM9 sensor has a pyroelectric element to measure a wide dynamic range of radiation, from <100nW to 100mW. It has an 8mm aperture and covers the spectral range from 0.15µm to 12µm. The system comes with the RMC1 chopper that is placed between the source and the RM9 sensor.

RM9 with Chopper | Laser Thermal Power Sensors | Power Sensors - Ophir
RM9 with Chopper | Laser Thermal Power Sensors | Power Sensors - Ophir
  • Pyroelectric with Chopper
  • Ø8mm
  • 0.15-12µm
  • 100nW-100mW
  • N.A.
  • Ø62 W x 21 D (mm)
  • N.A.
  • 5W/cm²
  • 3.5 s
  • N.A.
  • N.A.
  • 100mW
Need help finding the right sensor? Try our Sensor Finder

How should I clean my sensor?

First, clean the absorber surface with a tissue, using Umicore #2 Substrate Cleaner, acetone or methanol. Then dry the surface with another tissue. Please note that a few absorbers (Pyro-BB, 10K-W and 30K-W) cannot be cleaned with this method. Instead, simply blow off the dust with clean air or nitrogen. Don't touch these absorbers. Also, HE sensors (such as the 30(150)A-HE-17) should not be cleaned with acetone.
Note: These suggestions are made without guarantee. The cleaning process may result in scratching or staining of the surface in some cases and may also change the calibration.


Is the RM9 radiometer compatible with all Ophir power meters and PC interfaces?

It is fully compatible with these meters/interfaces:

  • Vega / Nova II (firmware vs. 2.44 or higher)
  • Juno (1.31 or higher)
  • StarLite (1.26 or higher)

It is partially compatible with Ophir’s other meters (Nova, LaserStar, USBI, Pulsar, and Quasar). It will function properly with these devices, except with an upper power limit of ~1 mW instead of 100 mW and with reduced accuracy, see specs for more details.


How can I maximize measurement accuracy with the RM9 radiometer?

The RM9 is only sensitive to signals chopped at 18 Hz, so placing the chopper as close to the laser source as possible will minimize stray light entering the chopper and being read as part of the signal.
The noise specification is based on a 10 second moving average. Set the power meter to average the measurements for optimal performance.
It is also recommended to zero the sensor before use. This is done by disconnecting the BNC cable between the RM9 sensor and the chopper or turning off the chopper. Then follow the regular instructions for zeroing that can found in your power meter or PC interface manual.


Can I measure pulsed laser power with the RM9?

Yes, but keep in mind that the RM9 will measure average power, not energy. Also, pulse rates below ~50 Hz may generate additional noise. Pulse rates close to 18 Hz may cause beat frequency issues.


Can I use my own chopper with the RM9?

Yes, but it must be set to a chopping frequency of 18 Hz.


Can I use the RM9 sensor to measure an 18 Hz pulsed source without the chopper?

If your source happens to be pulsed at 18 Hz, you cannot use the chopper, since this will generate very low frequency beat signals. However, it might be possible to use the RM9 directly with your laser source, as long as you can connect a BNC sync to the RM9 sensor. Contact us about your particular application to be sure this is the right solution for you.

  • RM9 with StarLab:

    Support available for RM9 with Vega, Nova II, Juno and StarLite in StarLab applications.
    The RM9 is supported by:
    NovaII / Vega meters (rev 2.44 and higher) press here
    StarLite meter (rev 1.26 and higher) press here
    Juno interface (rev 1.31 and higher) press here

RM9 Radiometer System: Very low powers, very broad spectrum RM9 Radiometer System: Very low powers, very broad spectrum

The RM9 system measures powers down to 100nW over a very broad spectral range, from UV to far IR.
This video introduces you to the RM9, and shows you how to use it.

Tutorials and Articles

Working in the Basement: Measuring Signals Below the Noise Floor with a Lock-In Amplifier

By Shimon Elstein, Senior Physicist


Customers that purchase the above items also consider the following items. Ophir-Spiricon meters and sensors include a standard manufacturers warranty for one year. Add a one year Extended Warranty to your meter or sensor, which includes one recalibration.