Focal Plane Assembly

HyspIRI-TIR has eight spectral channels measured with a single cooled bandgap Mercury Cadmium Telluride (MCT) detector array. Thirty two output signals at 10-13 Mpixels/sec enable the data to be read from the array for the 596 km swath with 60 m nadir resolution. Spectral separation is achieved using filters placed in close proximity to the detector array. Under each filter are 16 columns of 256 pixels. The signals from four of these columns will be read out and averaged using time-delay integration (TDI) to double the signal-to-noise ratio compared to a single pixel column. The columns of 256 pixels are aligned perpendicularly to the cross-track sweep direction (see figures below). The four columns of 256 pixels are read out in each of the eight spectral channels every 32 microseconds, resulting in a total data rate of 256 Mpixels/sec.The nominal Noise Equivalent Delta Temperature for the HyspIRI-TIR channels is also shown below.

Test Results

Measured Quantum Efficiency

This plot shows QE measured on a Process Evaluation Chip (PEC) detector fabricated on the same MBE layer as the SCA detector array.

Measured Focal Plane Dark Current

The dark current was measured to be ~183e- which exceeds the performance of the current baseline estimate of 235e-

Measured Focal Plane Well Size

The well depth was measured by taking the signal difference between a saturated and a starved frame multiplied by the gain is the well depth in electrons. The values are within the range expected for the HyspIRI-TIR array. Both Band 6 and 7 have the significant increase expected.

System measurement: Saturation temperature

Demonstrates that long-wavelength bands (8 and 12 μm in PHyTIR) do not saturate below 480 K, as required.

System measurement : Noise equivalent delta temperature (NEΔT)

Pixel temperatures retrieved in each band with 25 C blackbody, 10 minutes after calibration at required readout speed. PHyTIR would normally be calibrated every 2 seconds. Demonstrates yield (99.8 % response) within columns needed to define a spectral band and that PHyTIR meets S:N specification.

System measurement : Noise equivalent delta temperature (NEΔT)

Detail for previous images. Demonstrates that gains are available that meet required signal to noise at single pixel level. Required is < 200 mK.