Spectrograph is one of the most important tools in astronomical observation and can be used in research areas ranging from cosmology to exoplanet research. Conventional astronomical spectrograph using a diffraction grating is huge, posing great challenges to their thermal and mechanical stability, and they are also very expensive. This inevitably determines the need for new original innovations in future optical and near-infrared spectrograph technologies. The application of photonics in astronomical spectrograph in recent years has shown a great potential for miniaturizing the spectrograph which is mounted on the large telescopes. The new dispersion element named waveguide spectral lens (WSL)is proposed by Westlake University that different from the independent optical element in the conventional spectrograph, and it can realize the dual functions of both wavelength separation and focus. This kind of chip technology makes the structure more compact, and improves the design to expand the devices working in the communication band to the visible and near-infrared band, enabling the spectrograph based on this new technology to achieve astronomical observation in the visible band in the future. In order to fully understand the performance of this new dispersion element and its application potential in astronomy, we established two chip test platforms in the optical laboratory of Shanghai Astronomical Observatory, and analyzed the dispersion capability of the device by using the wavelength calibration method. In order to expand the range of the spectra, the two-dimensional cross-dispersion spectrum was realized by adding a cylindrical lens and a blazed grating in the laboratory. The solar spectrum is also observed using these two chips. The experimental results show that this new optical waveguide chip can be applied to the visible light band, and can be used as the dispersion element of astronomical spectrograph for astronomical applications. At present, the optical and mechanical design of the prototype of the spectrograph has been completed. In the future, the laboratory installation of the prototype will be completed to realize the on-sky observation as soon as possible.
The Earth 2.0 (ET) space mission has entered its phase B study in China. It seeks to understand how frequently habitable Earth-like planets orbit solar-type stars (Earth 2.0s), the formation and evolution of terrestrial-like planets, and the origin of free-floating planets. The final design of ET includes six 28 cm diameter transit telescope systems, each with a field of view of 550 square degrees, and one 35 cm diameter microlensing telescope with a field of view of 4 square degrees. In transit mode, ET will continuously monitor over 2 million FGKM dwarfs in the original Kepler field and its neighboring fields for four years. Simultaneously, in microlensing mode, it will observe over 30 million I < 20.5 stars in the Galactic bulge direction. Simulations indicate that ET mission could identify approximately 40,000 new planets, including about 4,000 terrestrial-like planets across a wide range of orbital periods and in the interstellar space, ~1000 microlensing planets, ~10 Earth 2.0s and around 25 free-floating Earth mass planets. Coordinated observations with ground-based KMTNet telescopes will enable the measurement of masses for ~300 microlensing planets, helping determine the mass distribution functions of free-floating planets and cold planets. ET will operate from the Earth-Sun L2 halo orbit with a designed lifetime exceeding 4 years. The phase B study involves detailed design and engineering development of the transit and microlensing telescopes. Updates on this mission study are reported.
An ultra-compact optical spectrograph (~43x16x13cm) is developed using a new optical arrayed waveguide technique based on waveguide spectral lenses (WSL). The WSL is an evolved version from the arrayed waveguide grating design can achieve simultaneous spectral dispersion and image focusing onto the detector plane at designed distance. Despite its compact size, the instrument maintains high optical throughput and provides a wide range of spectral resolution (R~200-2000 at 600-950 nm). The spectrograph's design and the results of laboratory testing will be reported.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.