Developing achromatic coronagraphic optics for LMIRCam and the LBT

The Apodizing Phase Plate (APP) is a simple optic that provides coronagraphic suppression of diffraction without the need for any focal plane occulters. We present the design of a broadband APP (the BAPP) for LMIRCam that is optimised for the direct imaging of cool extrasolar giant planets around nearby stars at thermal infrared wavelengths. These optics have a high throughput and require no precision alignment. We cover earlier results using a chromatic APP, the basic principle and manufacture of the optic.