I am enthusiastic in instrumental development for both optical and radio astronomy.
I believe that some technologies in optical astronomy can be made useful in radio astronomy and vice versa.
I am also interested in astrophysical and cosmological observation and experiments, expecially in transient events.
CHORD is a next-generation radio telescope currently under development and construction with effort from pan-Canadian astronomers, together with international collaboration.
Designed as an ultra-wideband (300-1500MHz), "large-N, small-D" telescope with VLBI outrigger stations, CHORD's primary goals include conducting advanced cosmological and astrophysical measurements and studying radio transients.
I am developing the analog signal chain and analog power distribution circuit for the CHORD array together with students.
A prototype of the analog signal chain, with amplifiers, tranmission cables and analog filters
A prototype of power distribution system to power the amplifiers
Optical fibers, with their immunity to electromagnetic interference, can offer long-range signal transmission for radio telescopes, substituting coaxial cables.
We propose a novel, economical approach by adapting commercial digital Small Form-factor Pluggable (SFP) modules for analog Radio-over-Fiber (RFoF) usage.
By repurposing these modules with tailored analog circuits, we can transmit RF signals up to several gigahertz.
Initial tests with a 3m LC fiber achieved flat, low-loss transmission for bands greater than 2 GHz.
In the Ultra-Fast Astronomy (UFA) program lead by Prof. George F. Smoot, we aim to survey the optical night sky on millisecond and shorter time scales, where we expect to see transients or variabilities from astronomical targets.
We designed a position sensitive silicon photomultiplier (PS-SiPM) based single photon imager, which we call the Single Photon Imager for Nanaosecond Astrophysics (SPINA). When an photon is detected on the PS-SiPM, a photo-electron is generated and amplified into a electric pulse, which is then distributed into the four anodes of the sensor. The readout system on the SPINA system will capture their pulse height, and interpret them as a time series of position, pulse strength with 8ns timing accuracy. We can then interpret this data stream of photon into Ultra-Fast light curve of astronomical objects.
I designed and developed the electronic system, cooling system and mechanical mounting of the SPINA system as my Ph.D. thesis project.
Reading the high-speed analog pulse from the PS-SiPM detector is one of the challenge in the SPINA system, especially when we wanted to do it simple, cost efficient and on a single electronic board.
After some testing and experiments, we found commercial Analog Front-End (AFE) developed for medical ultrasound act as a good readout for SiPM system. The AFE5818 from Texa Instrument can support 16 channels readout with 54dB, Low-noise amplification, in-chip tunable filters and 14bits, 65Msps ADC readout.
We designed our readout system based on the AFE5818 and a Field Programmable Gate Array Multipurpose System on Chip (FPGA-MPSoC). This readout system sucessfully capture the signal from our PS-SiPM, and perform realtime processing to decode the position information of each event. The readout system also generate bias voltage to drive the PS-SiPM with individual channel tunabing ability.
We installed the SPINA system on the Nazarbayev University Transient Telescope at the Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) for the first On-Sky testing at Jul 2022. Here is a timelapse video of us installing and testing the SPINA system.
Currently, we are testing a few different systems, including the ROACH2 board from minicom electronics, and designing a readout system base on I/Q modulator-demodulator and a FPGA board with GHz ADC/DACs.
Lau, A. W. K., Nurzhan, S., Zhanat, M., Chan, Y. Y., Shafiee, M., Grossan, B. & Smoot, G. F. (2023). Initial On-Sky Performance testing of the Single-Photon Imager for Nanosecond Astrophysics (SPINA) system, In IEEE Transactions on Instrumentation and Measurement, v. 72, October 2023, article number 10285601
Lau, A. W. K., Chan, Y. Y., Shafiee, M., Smoot, G. F., & Grossan, B. (2022). Development of position-sensitive photon-counting imager for Ultra-Fast Astronomy, In X-Ray, Optical, and Infrared Detectors for Astronomy X (Vol. 12191, pp. 312-329). SPIE.
Lau, A. W. K., Shafiee, M., Smoot, G. F., Grossan, B., & Zhanat M.(2020). On-sky silicon photomultiplier detector performance measurements for millisecond to sub-microsecond optical source variability studies Journal of Astronomical Telescopes, Instruments, and Systems 6.4 (2020): 046002
Oral Presentation: Development of position-sensitive photon-counting imager for Ultra-Fast Astronomy, In SPIE Astronomical Telescopes + Instrumentation 2022: X-Ray, Optical, and Infrared Detectors for Astronomy X
Google Scholar Profile
I joined Prof. KS Wong's laboratory for my final year project in undergraduate. I developed the optics, electronics and firmware of a laser excited scanning confocal microscope for material characterization. The system is still being used and upgraded currently.
This was my first research project during undergraduate studies, where we develop fast algorithm on estimating reachability problem of low thrust spacecrafts. We managed to build a O(N*k) algorithm compare to the traditional O(Nk) cost. The results were presented in IAC2017 conference.