Wavelength-agile telescope system with diffractive wavefront control and acousto-optic spectral filter
Programmable diffractive optics (PDO) based on liquid-crystal (LC) technology has been demonstrated as a wavelength-tunable technology for compensating large aberrations over limited instantaneous spectral bandwidths. Acousto-optic tunable filters (AOTFs) based on acousto-optic Bragg diffraction have been demonstrated as a wavelength-tunable technology for selecting narrow spectral bands from white light with high rejection ratios. These technologies are integrated into a telescope system that includes a conventional primary mirror utilized off axis with more than 40 waves of aberration to view a white-light-illuminated object bar chart. A high-resolution LC PDO, situated in a pupil plane, compensates for the large primary mirror aberration. The AOTF, operating in an image plane, rejects light outside a 2-nm spectral band centered about the wavelength at which the modulo λ phase profile of the PDO is defined. Wavelength-tunable narrowband imaging is achieved by synchronously tuning the PDO and AOTF over a 100-nm spectral range. Near-diffraction-limited image quality is demonstrated.