The development of millimeter-wave absorbers for astronomical instruments is an important area of research regarding stray light suppression. Millimeter-wave absorbers for space missions should be selected based not only on their broadband performance at oblique incidence but also on their polarization characteristics, weight, and radiation tolerance. LiteBIRD is a space telescope designed to test inflationary theories by observing the polarization of the cosmic microwave background (CMB). The Low-Frequency Telescope (LFT) on board LiteBIRD needs to know the far side lobes at the −56 dB level, so surrounding it with millimeter-wave absorbers suppresses stray light. Because even the smallest stray light reflection may cause non-negligible far side lobes in the millimeter-wave absorber inside the telescope, it is necessary to accurately measure the reflectance of the millimeter-wave absorber not only specular reflection but also diffuse reflection. We performed near-field reflection measurements of a new lightweight absorber for two polarizations with a 30 degree angle of incidence in the frequency range between 70 GHz and 110 GHz. Measurements showed a reflectance of -16 dB for TE and -19 dB for TM, lower than the industry standard Eccosorb AN-72. In addition, we evaluated radiation tolerance and confirmed that the difference in reflectance before and after exposure was within 3 dB.
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.