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NASA EOS-AURA High Resolution Dynamics Limb Sounder (HIRDLS)

1990 - 2002

Project overview

The High Resolution Dynamics Limb Sounder (HIRDLS) instrument is a Limb Viewing Radiometer which was launched on the NASA EOS-Chem Satellite in 2004. Measurements of radiance from the thermal emission of trace chemical elements in the atmosphere is performed through a cooled infrared optical system. It has 21 spectral channels precisely defined by our filters contained within a focal plane detector assembly array. We are also responsible for the 21 "Ghost Image" suppressing filters positioned at the cold (60K) detector plane. These are very small in size - 1180mm x 440mm.

Our work is to make the two sets of 21 precision bandpass filters together with ultra broadband antireflection coatings for the lenses and windows of the instrument. The work is funded by a NERC research grant. Our responsibilities as co-investigators in the project include the complete end to end spectral design of the instrument. The filters are the most demanding we have ever had to make, combining as they do high spectral placement precision, the need to size by sawing, sub millimetre size, cryogenic use, and stringent quality assurance including state of the art spectral measurements of the finished items.

Delivered hardware

Description Filter Type Quantity Wavelength Region Substrate Material Dimensions
Cold Filters Narrow bandpass filter 21 channels 6.0 - 18.0 µm Germanium (Ge) 1.39 mm L x 0.63 mm W x 0.45 mm T
Warm Filters Narrow bandpass filter 21 channels 6.0 - 18.0 µm Germanium (Ge) 7.60 mm L x 3.40 mm W x 0.88 mm T
Dewar Window Broadband antireflection coating 1 channel 6.0 - 18.0 µm Zinc Selenide (ZnSe) 30.0 mm Dia x 2.0 mm T
Lenses Broadband antireflection coating 2 channels 6.0 - 18.0 µm Germanium (Ge) 64.0 mm Dia x 3.0 mm T
Gas Cell Window Wide bandpass filters 4 channels 6.3 - 16.3 µm Germanium (Ge) 25.4 mm Dia x 1.5 mm T




NASA Aura launch and mission science objectives

Damaged HIRDLS instrument still provides valuable data

Further information

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