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This study presents a technique for measuring the centering error of a lens. The technique uses power analysis and is highly accurate. The module is designed by a prism that is patterned using a subwavelength grating combined with a reflection-centering system by using the −1st-order rays at 5 mW and 650 nm. The optical axis error is tested and analyzed by the powermeter by using Snell’s law and diffractive characteristics. The resolution of the optical-centering error in the system is amplified by a factor of 4 compared with the centering error measuring system based on autocollimation. The technique proposed in this study improves the sensitivity of the instrument and reduces the requirements of the sensor at the end side based on the direction or energy variation of the light.

In this study, a high-precision and low-cost instrument was developed for the measurement of the wedge angle of wedge plates. The module was designed using two prism-patterned subwavelength gratings, with the −1 order rays extracted using a semiconductor laser beam-splitting device. Subsequently, in reference to Snell’s Law and the diffractive characteristic, the wedge angles of wedge plates were tested and analyzed when the two points on the movable receiving screen were overlapped through adjustment of the distance. This result revealed that the proposed system achieved sub-second ultimate resolution for the wedge angles of the wedge plate under a 1-µm precision requirement for measuring instruments.

A compact cryogenic corrugated feedhorn consists of 31 aluminum platelets is designed and tested for next generation wide bandwidth radio astronomical receivers. Compared with direct machining and electroforming, the fabrication cost can be easily reduced and deep groove can be easily achieved. At room temperature, it covers 30-50 GHz with better than 30 dB return loss and < -30 dB cross-polarization at band-center and < -27 dB at band-edge. Beam patterns are scanned after the feedhorn is cooled down to 7K. Both wide bandwidth and low cross-polarization level are achieved. The illumination patterns feature better than 99.77% polarization efficiency and 3.72% beam squint. Due to the compact structure, no degradation in performance is found after thermal cycling.

A short-backfire antenna (SBA) with corrugated structure on the aperture edge of the main reflector is designed to suppress sidelobe and enhance the isolation. The corrugated SBA is suitable for closed-pack antenna array. Early prototype antenna measured results indicate that the radiation pattern is well fit to the design and simulation. The simulation also indicates that the spill over temperature is below 11K over 700- 900MHz if the SBA is integrated to the 100-meter Green Bank Telescope.

The Atacama Large Millimeter/submillimeter Array(ALMA) Band 1 receiver covers the 35-50 GHz frequency band. Development of prototype receivers, including the key components and subsystems has been completed and two sets of prototype receivers were fully tested. We will provide an overview of the ALMA Band 1 science goals, and its requirements and design for use on the ALMA. The receiver development status will also be discussed and the infrastructure, integration, evaluation of fully-assembled band 1 receiver system will be covered. Finally, a discussion of the technical and management challenges encountered will be presented.

The prototype cartridges for ALMA Band-1 receivers have been developed, based on the key components developed in ALMA Band-1 consortium laboratories. The prototype cartridges for each receiver consist of two parts, cold cartridge assembly and warm cartridge assembly. The cold cartridge assembly (CCA) consists of horn antenna, orthomode transducer and a pair of 35-52 GHz cold low-noise amplifiers, the amplified signals of both polarizations are transmitted to warm cartridge assembly by long waveguide sections. In warm cartridge assembly (WCA), two major modules incorporated, down-converter assembly including warm low-noise amplifier, high-pass filter, mixer and 4-12 GHz IF amplifier, and local oscillator based on a 31-40 GHz YIG-tunes oscillator. The frequency range is based on the upper sideband scheme. Based on the measured performance of the key components, the expected noise performance of the receiver will be 26-33K.

A series of 31.3-45.0GHz millimeter-wave components including 31.3-45GHz low-noise amplifiers, band-pass and highpass filters, a cascode PHEMT mixer, and 4-12GHz IF amplifiers are developed in Taiwan. The local oscillator for band- 1 is also developed, including the phase-locked GaAs HBT MMIC voltage-controlled oscillator cascaded by a buffer amplifier and a baseline design based on a YIG-tunes oscillator with active frequency doubler. The measured RMS jitter of the HBT VCO LO is around 51 fs and the version of YIG is less than 40fs over 1K to 1MHz frequency offset.

The Band-1 receiver front-end cartridges for Atacama Large Millimeter Array, which covered 35–50 GHz frequency range, are now in preproduction stage. For the first three preproduction cartridges, the measured receiver noise temperature is less than 16–31K for any combination of the inband RF and LO frequencies. The measured gain flatness, even with the limitation of the optical window of the cryostat and the broadband matching of the cryogenic amplifiers, is typically lower than 5 dB over any 2GHz window. Extracted aperture beam efficiency is typically higher than 80% over the full frequency range. The crosstalk over the orthogonal channel is lower than −63 dB. For the suppression of the unwanted lower sideband, the imaged band suppression is higher than 20 dB for the worst case and around 30 dB typically.