High Accuracy Pointing for Quasi-Optical THz Mixer Arrays

Jose Rui Gaspar Silva, Matvey Finkel, Wouter M. Laauwen, Menno Westerweld, Nikhil More, Abram Young, Craig Kulesa, Christopher Walker, Floris Van Der Tak, Jian Rong Gao

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


We report a high accuracy pointing technique for quasi-optical hot electron bolometer (HEB) mixers in focal-plane arrays designed to operate at 1.4, 1.9, and 4.7 THz. The high accuracy pointing is achieved by prealignment of a HEB chip to a lens, measuring the angular error of each mixer in an array assembly, and then realignment of the chip to the same lens to correct the error. The realigned mixers, using 5 mm diameter Si elliptical lenses designed for operation at 4.7 THz, show a final pointing error distribution with an average (μ) = 0.13° and standard deviation (σ) = 0.06°, with respect to the normal direction of the respective array plane. Those using 10 mm diameter lenses designed for operation either at 1.4 or 1.9 THz, show μ = 0.08° and σ = 0.03°. We demonstrated our pointing technique in five 4×2 HEB focal plane arrays developed for NASA's balloon borne GUSTO THz observatory. Our results corroborate the simulated beam steering factors used to calculate the realignment corrections. With the unprecedented pointing accuracy at the high frequencies, our technique can significantly facilitate the use of lens-antenna, quasi-optical mixers for future focal-plane arrays, which is able to compete with traditional feedhorn-waveguide mixer arrays, operated typically below 1 THz, for astronomical instrumentation.

Original languageEnglish (US)
Pages (from-to)53-62
Number of pages10
JournalIEEE Transactions on Terahertz Science and Technology
Issue number1
StatePublished - Jan 1 2022


  • Antenna arrays
  • antenna radiation pattern
  • beam steering
  • cryogenic
  • lenses
  • terahertz radiation

ASJC Scopus subject areas

  • Radiation
  • Electrical and Electronic Engineering


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