  We present the data reduction pipeline, MEAD, for Arizona Lenslets for
Exoplanet Spectroscopy (ALES), the first thermal infrared integral field
spectrograph designed for high-contrast imaging. ALES is an upgrade of LMIRCam,
the $1-5\,\mu$m imaging camera for the Large Binocular Telescope, capable of
observing astronomical objects in the thermal infrared ($3-5\,\mu$m) to produce
simultaneous spatial and spectral data cubes. The pipeline is currently
designed to perform $L$-band ($2.8-4.2\,\mu$m) data cube reconstruction,
relying on methods used extensively by current near-infrared integral field
spectrographs. ALES data cube reconstruction on each spectra uses an optimal
extraction method. The calibration unit comprises a thermal infrared source, a
monochromator and an optical diffuser designed to inject specific wavelengths
of light into LBTI to evenly illuminate the pupil plane and ALES lenslet array
with monochromatic light. Not only does the calibration unit facilitate
wavelength calibration for ALES and LBTI, but it also provides images of
monochromatic point spread functions (PSFs). A linear combination of these
monochromatic PSFs can be optimized to fit each spectrum in the least-square
sense via $\chi^2$ fitting.
