Unfortunately, there is not a perfect detector for the entire infrared region. As a consequence, there are a number of factors to consider when choosing an infrared detector for your measurement, including
- Spectral range
- Cooling method
- Response speed
It is often not possible to optimize all the desired factors in a single detector; some compromises will be needed. For a detailed description of these factors, please refer to "Characteristics and use of infrared detectors." Some of the more commonly used detectors at our beamline are listed below. For a complete listing of the available infrared detectors, please see our detector list.
| Detector|| Spectral Range / cm-1||Sensitivity (D*) / cm•Hz1/2•W-1 ||Cooling ||Speed (Time constant) / s |
|DTGS|| 10-11,000 (depends on window material)|| ~2 x 108||Room Temp||~10-2|
|MCT A ||650-11,000|| ~2 x 1010||Liquid N2||~10-6|
|MCT B ||400-11,000|| ~4 x 109||Liquid N2||~10-6|
|Si Bolometer ||3-5000|| ~5 x 109||Liquid He||~10-3|
Our infrared microscopes (Beamlines 1.4.3 and 1.4.4) are equipped with an MCT A detector because this detector provides the best sensitivity and speed over a broad spectral range covering the entire mid-infrared and most of the near-infrared (up to ~11,000 cm-1). One downside to these detectors is that they require liquid nitrogen. The dewars, however, last > 8 hours and liquid nitrogen is readily available at the ALS.