Absolute Terahertz Power/Energy Meter


A new USB version of our successful absolute power meter support unit is now available,

with continuous FFT display of noise and dynamic as well as digital readout of power levels.


power meter system


The system is comprised of two parts:

  1. The power meter head.
  2. The support unit, based on a National Instruments USB-6211 data acquisition module.


  • Measures power in free-space beams
  • Displays power on a computer
  • Fully automatic absolute calibration using electrical film heating under software control
  • Frequency dependent window loss correction
  • Accuracy better than 10%
  • NEP typically 5µW/Hz½
  • For energy measurement the typical NEJ is about 1µJ
  • Broad Band: 30GHz to 3THz and beyond
  • Sensitive Area greater than 30mm in diameter


The Head

The head is a photo-acoustic detector using a closed air-cell and a pressure transducer.

Calibration is provided by ohmic heating of a thin metal film within the cell.

power meter top view

power meter front view


The Support Unit

The support unit is based around a National Instruments USB-6211 data acquisition module.

Additional electronics have been added to provide film heating for calibration and to amplify

the signal from the head's microphone pressure sensor. The compiled software, written in

LabVIEW, implements a lock-in amplifier and displays the microwave power.

support unit

power meter software


Support Downloads

Transmission Data


Updated transmission data, with preliminary measurements above 3.5THz.


version 3.2.2

Update for Windows Vista and higher. Late beta version - see below.  Run setup.exe from the .zip file to install the software.

version 2.0

Software for the original support unit based on the NI PCI-6023E A/D card.


Version 3.2.2 is compiled for use with Microsoft Windows Vista, 7, 8 and 8.1 (32 and 64 bit) with National Instruments LabVIEW software for 2014 and later.  This version will continue to provide full compatibility with LabVIEW for the next few years.

The earlier 3.2.1 software uses NI LabVIEW Run-Time Engine version 8.6. NI have ceased including this on the DVDs released with new NI boards.  The compatibility of the NI software can be checked by running the NI MAX software and selecting the Software tree.  The entry LabVIEW Run-Time 8.6 must be included within this tree.  If it is not, then the compatibility can be added by following this link. Please contact Kevin Pike if you have any problems with this.  This version was compiled for use with Microsoft Windows XP.

Version 3.2.2

This version can be used with the latest Microsoft and National Instruments software.  It is considered a late beta version because it is currently not possible to change the Transmission Data by copying in an updated file.


version 3.2.2

Manual for the current USB support unit and version 3.2.2 of the software.

version 2

Manual for the original head and support unit based on the NI PCI-6023E A/D card.


Richard Wylde - Thomas Keating Ltd - This email address is being protected from spambots. You need JavaScript enabled to view it.