Status and first results of the NASA IRTF adaptive secondary mirror

TNO and partners at University of Hawai’i (UH), the NASA InfraRed Telescope Facility (IRTF), and the Center for Adaptive Optics (CfAO) at UCSC have been working on the realization of a 244 mm Adaptive Secondary Mirror (ASM) for the NASA IRTF called the IRTF-ASM-1. After successful performance testing of several laboratory prototypes, this project provided the first on-sky demonstration of TNO’s ASM technology at M2 location with an optically powered mirror shell. <br/> <br clear="all"/> The ASM is designed to retrofit the current passive M2. The ASM consists of a 244mm-diameter slumped convex aspherical mirror shell, manipulated by 36 hybrid variable reluctance actuators mounted on a light-weighted backing structure. The mirror shell is manufactured to the required accuracy at reduced cost through slumping by UCSC. The mirror shell is finished to final figure with Magnetorheological Finishing (MRF) by TNO before it was coated. <br/> <br clear="all"/> The ASM was shipped to UH in Hilo in February 2024, where performance was tested in the lab. The IRTF ASM saw ‘first light’ on telescope on the 23^rd of April, already achieving stable closed-loop performance that was diffraction limited at the H-band (1.62 microns) with a long-exposure Strehl ratio of 35%-40% in sub-arcsecond seeing during the first night. <br/> <br clear="all"/> This paper will report on the status and first results of the IRTF ASM, including the latest status of the deformable mirror technology at TNO and an outlook to a second generation IRTF ASM with improved dynamic performance and increased actuator count.