The National Astronomical Research Institute of Thailand (NARIT) is currently developing a new kind of focal reducer for the 2.4 m Thai National Telescope (TNT). The objective is to image a circular Field Of View (FOV) of 15 arcminute diameter with an image quality close to the seeing limit over the spectral bands B, V, R and I. This focal reducer comprises one doublet lens L1 located on one robotic rail mounted on the telescope fork and one triplet lens L2 mounted on the instrument cube in front of the camera. First, we remind the specifications and the optical design of the instrument. Second, we present the method used to assemble the lenses inside the barrels. Third, we describe the procedure we have used to integrate the focal reducer on the TNT. We describe the robotic rail on which L1 is mounted and we present the results of the wavefront measurement performed to verify the optical quality of the TNT equipped with L1. We also describe the operations of the installation of L2, the filter wheel and the camera on the telescope. Fourth, we present the preliminary performance of the focal reducer measured on-sky with the TNT. We show that the focal reducer provides a resolution close to 1.5’’ over a FOV equal to 12’x12’ limited by the dimensions of the current filters. We also show that the plate scale is equal to 0.6’’/pixel and is stable over the B, V, R and I bands.
The National Astronomical Research Institute of Thailand (NARIT) has developed since June 2014 an optical laboratory that comprises all the activities and facilities related to the research and development of new instruments in the following areas: telescope design, high dynamic and high resolution imaging systems and spectrographs. The facilities include ZEMAX and Solidwork software for design and simulation activities as well as an optical room with all the equipment required to develop optical setup with cutting-edge performance.
The current projects include: i) the development of a focal reducer for the 2.3 m Thai National Telescope (TNT), ii) the development of the Evanescent Wave Coronagraph dedicated to the high contrast observations of star close environment and iii) the development of low resolution spectrographs for the Thai National Telescope and for the 0.7 m telescopes of NARIT regional observatories. In each project, our activities start from the instrument optical and mechanical design to the simulation of the performance, the development of the prototype and finally to the final system integration, alignment and tests. Most of the mechanical parts are manufactured by using the facilities of NARIT precision mechanical workshop that includes a 3-axis Computer Numerical Control (CNC) to machine the mechanical structures and a Coordinate Measuring Machine (CMM) to verify the dimensions.
In this paper, we give an overview of the optical laboratory activities and of the associated facilities. We also describe the objective of the current projects, present the specifications and the design of the instruments and establish the status of development and we present our future plans.