The Spectral Master 12-550 Mark III Radiometer system provides versatility for almost any IR measurement task. The system allows simple field installation of various types of detectors, filters and optics, including Spectral CVF Filters for spectral measurements. The High performance Mercury Cadmium Telluride and Indium Antimonide two-color detector option offers the highest sensitivity and covers the 1 to 16 um range, without changing detectors. Virtually any filter can be installed in the system for bandpass energy measurements in the Visible, Near, Mid and Far Infrared bands.

• High Resolution 4” Cassegrain Optical System with Interchangeable Detector and Optical Modules.
• Spectral Scanning or Discrete Bandpass Measurements All With One System.
• Expand the Range FROM 0.4 to 20 um with Interchangeable Detector and Filter Modules
• COMPURAD Spectral and Bandpass Data Analysis Software

Optical System:
The Mark III's optical system is a 100 mm, Dall-Kirkham f/2 Cassegrain system, with focus adjustable from 1 meter to infinity. Optical Field of View angles from 0.5 milliradians (0.03 degrees) to 17.5 milliradians (1 degree) are available with this Cassegrain system. Wide field of view kits for the 1-28 degree FOV range are available as drop in lens kits. A 2.5 milliradian field of view is most typically selected to offer the best sensitivity and the sharpest field shape, but the system can be configured with any field angle desired for your particular application.

Through-lens, non-parallax visual sighting provides the most accurate alignment of visual positioning versus actual system sensing field of view, and the spring loaded sighting lever moves out of the optical path to eliminate beam-splitter losses. Precision aspheric matched mirrors provide clear sharp infrared field of views. Focus adjustment is provided with a precision optical rack assembly that ensures smooth motion and exact positioning to ensure constant field uniformity and optical alignment at any distance.

Internal Reference Cavity:
An in-line reference cavity is used with gold plated chopper vanes to provide exceptional stability and accuracy. The optical system is tuned so that the chopper vane causes the detector to view a controlled reference cavity each time a vane passes in front of the cavity. This provides a stable, known reference for the system. The reference can be heated for ambient and low temperature measurements to provide a high contrast between the ambient target and the internal reference. The delta signal produced is much larger than that of a system with an ambient cavity, and therefore provides much higher signal to noise levels.