Related Experiment Video
Updated: Jun 17, 2026

A Multimodal Wide-Field Fourier-Transform Raman Microscope
Published on: December 30, 2025
Infrared modulation by means of frustrated total internal reflection
R W Astheimer1, G Falbel, S Minkowitz
1Barnes Engineering Company, Stamford,Connecticut, USA.
Abstract:
Most infrared systems and instruments require mechanical chopping or scanning mechanisms for modulating the radiation signal. For some applications, particularly in space, it is desirable to eliminate sliding or rotating mechanical components. One means of accomplishing this is by means of frustrated internal reflection. Spacings and motions of the order of 0.05 wavelength are necessary which are difficult to control in the visible spectral region, but, in the 8-12 micro infrared region, the scale is twenty times greater, and a modulation cell based on this principle becomes quite practical. The characteristics of frustrated internal reflection are briefly summarized, and a modulation cell constructed on these principles is described. This cell has a clear aperture of 12.7 mm and produces 80% modulation of 10- micro radiation. A lead zirconate titanate piezoelectric stack is used for moving the frustrating element, which gives a frequency response higher than 6 kc/sec.
Related Concept Videos
Total Internal Reflection Fluorescence Microscopy
Attenuated Total Reflectance (ATR) Infrared Spectroscopy: Overview
The ATR process begins by directing a beam...
IR Spectrometers
Infrared (IR) Spectroscopy: Overview
Different compounds display unique properties due to their...
IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
IR Spectrum
Transmittance is defined as the ratio of the radiant power passing through a sample to that from the radiation's source. Multiplying the transmittance by 100 gives the percent transmittance (%T), which varies between 100% (no absorption) and 0% (complete...

