Interlock and safety systems (ILS) play a significant role in the safe and reliable operations of cyber-physical systems such as optical telescopes. We performed a comprehensive hazard analysis to identify and classify various hazard issues and their severities together with the required actions. ILS has been deployed in reliable PLC platforms in the INO340 telescope to deliver all related functionalities in safe and stable conditions. Since ILS provides dedicated engineering panels for specific operators, we have also developed a specific Alarm/warning management system for the operator/astronomer applications in parallel. In this paper, we briefly present the INO340 telescope hazard analysis process, ILS architecture and development methodologies, and Alarm/warning management system design and implementation.
The Active Optics System (AOS) of the Iranian National Observatory 3.4 m telescope (INO340) is designed to support and deform the M1 and to adjust the position of the M2 with the purpose of optical aberrations’ compensation. Sixty active axial pneumatic actuators and 32 passive lateral actuators support M1 axially and laterally, respectively. The arrangement and force vectors of the lateral actuators are optimized in such a way that minimum deformation on M1 occurs. There are 3 axial and 3 lateral fixed-points as positioning detectors for M1, and an accurate hexapod keeps M2 in the appropriate position. M1 surface shape and M2 positions are actively controlled by AOS during telescope operations using either a look-up table in open-loop control or the wavefront error in closed-loop control to achieve the best image quality. There are three levels of the control loop in AOS: 1- A proportional controller for a single actuator, 2- Inner-loop control to equilibrate M1 within the bandwidth of 1 [Hz], 3- Outer-loop control to remove optical aberrations within the bandwidth of 0.01 [Hz]. A test setup for the axial actuator and an Alt-simulator setup are provided to design and optimize a proportional controller for a single actuator and to test the inner-loop control. In this paper, the mechanical, control, and software designs for INO340 AOS are presented.
An active optics algorithm is developed for the Iranian National Observatory 3.4 [m] telescope (INO340). The primary mirror (M1) and the secondary mirror (M2) are considered flexible and rigid, respectively. M1-Support consists of 60 active axial actuators (AAC), 32 passive lateral actuators (LAC), three axial hard-points (AHP), and three lateral hardpoints (LHP); and an accurate hexapod supports M2. M1 surface shape and M2 positions are actively controlled using an active optics system (AOS) to reach the best image quality. Correction can be done using either a look-up table in open-loop control or the wavefront error in closed-loop control. This paper presents the algorithm and the strategy of INO340 active optics. In this regard, relevant extracted matrices for the INO340 active optics algorithm are derived. The Shack-Hartmann sensor probes the accumulated aberrations and provides a square matrix as feedback. By decomposing the aberrations into the Zernike polynomials, tip-tilt, defocus, and coma aberrations are eliminated by adjustment of M2 positions and other aberrations are removed by deforming the flexible M1. The effective mechanical modes of M1 are selected based on the AACs’ force amplitude, and root mean square (RMS) of the residual surface. The percentage of residual surface error and set of axial forces are shown for each mechanical mode. As a result, mechanical modes No. 1 to 9 and No. 12 to 16 can be corrected. Finally, the algorithm is used to remove the remained aberration after the polishing process, which shows the residual surface after compensation and the required set of AACs’ force.
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