Hiroki Fujimori

Hyper Suprime-Cam: development of the CCD readout electronics

Hyper Suprime-Cam (HSC) employs 116 of 2k×4k CCDs with 464 signal outputs in total. The image size exceeds 2 GBytes, and the data can be readout every 10 seconds which results in the data rate of 210 Mbytes / sec. The data is digitized to 16-bit. The readout noise of the electronics at the readout time of 20 seconds is ~0.9 ADU, and the one with CCD is ~1.5 ADU which corresponds to ~4.5 e. The linearity error fits within ± 0.5 % up to 150,000 e. The CCD readout electronics for HSC was newly developed based on the electronics for Suprime-Cam. The frontend electronics (FEE) is placed in the vacuum dewar, and the backend electronics (BEE) is mounted on the outside of the dewar on the prime focus unit. The FEE boards were designed to minimize the outgas and to maximize the heat transfer efficiency to keep the vacuum of the dewar. The BEE boards were designed to be simple and small as long as to achieve the readout time within 10 seconds. The production of the system has been finished, and the full set of the boards are being tested with several CCDs installed in the HSC dewar. We will show the system design, performance, and the current status of the development.

Back-End Readout Electronics for Hyper Suprime-Cam

We have developed the back-end readout electronics (BEE) for Hyper Suprime-Cam (HSC). HSC is the next generation wide-field camera to be mounted on the 8.2-meter diameter Subaru Telescope in Hawaii. It employs 116 pieces of 2k × 4k Charge Coupled Devices (CCDs) to cover a 1.5 degrees diameter field of view. The electronics system for HSC can be divided into two parts: the front-end electronics (FEE) in which analog signals from CCDs are processed and the BEE which is a digital component of the readout electronics. The BEE sends a readout clock to the CCD and FEE, receives the image data from the FEE and sends them to the data acquisition computers. The electronics are required to read the CCDs at the rate of 243k pixel/sec/CCDoutput while suppressing the readout noise smaller than about 4 electrons, so that the 2.3G byte of an image data can be read within about 10 seconds. We designed the BEE as 3U Euro-card system with seven slots (140 mm × 180 mm × 130 mm) to achieve all the requirements for HSC. The maximum readout speed was 265k pixel/sec/CCDoutput and the readout noise was smaller than 3 electrons, including the clock jitter noise of 0.1 electrons. We concluded that our back-end readout electronics have sufficient performance for HSC.

Prototype readout module for hyper suprime-cam

The Hyper Suprime-Cam (HSC), the next generation wide-field camera proposed for the Subaru Telescope operated by the National Astronomical Observatory of Japan, employs ∼ 110 2k × 4k Charge Coupled Devices (CCDs) to cover a 1.5-degree diameter field of view. It is a requirement that the readout electronics are able to send ∼ 2 Gbytes of image data in 10 seconds while maintaining low noise. In addition, the readout system should be small and light in order to be mounted inside the camera. We have developed a prototype readout module for the Back End Electronics (BEE) of the readout system. The BEE provides a digital interface between the analog front end of the readout system and the data acquisition system (DAQ system). Two Gigabit Ethernet links are employed for data transfer between the BEE and the DAQ system. The size of our BEE module is 149 mm × 79 mm × 12 mm. We measured the data transfer rate from the readout module to the DAQ system and also estimated the noise. The data rate achieved full Gigabit Ethernet bandwidth and the noise was sufficiently low. Thus, we concluded our prototype readout module satisfied the required specification.

Hyper Suprime-Cam: performance of the CCD readout electronics

Hyper Suprime-Cam (HSC) employs 116 pieces of 2k×4k fully-depleted CCD with a total of 464 signal outputs to cover the 1.5 degrees diameter field of view. The readout electronics was designed to achieve ~5 e of the readout noise and 150000 e of the fullwell capacity with 20 seconds readout time. Although the image size exceeds 2G Bytes, the readout electronics supports the 10 seconds readout time for the entire CCDs continuously. All of the readout electronics and the CCDs have already been installed in the camera dewar. The camera has been built with equipment such as coolers and an ion pump. We report the readout performance of all channels of the electronics extracted from the recent test data.

Back-end readout electronics for Hyper Suprime-Cam

We have developed the back-end readout electronics (BEE) for Hyper Suprime-Cam (HSC). HSC is the next generation wide-field camera to be mounted on the 8.2-meter diameter Subaru Telescope in Hawaii. It employs 116 pieces of 2k × 4k Charge Coupled Devices (CCDs) to cover a 1.5 degrees diameter field of view. The electronics system for HSC can be divided into two parts: the front-end electronics (FEE) in which analog signals from CCDs are processed and the BEE which is a digital component of the readout electronics. The BEE sends a readout clock to the CCD and FEE, receives the image data from the FEE and sends them to the data acquisition computers. The electronics are required to read the CCDs at the rate of 243k pixel/sec/CCDoutput while suppressing the readout noise smaller than about 4 electrons, so that the 2.3G byte of an image data can be read within about 10 seconds. We designed the BEE as 3U Euro-card system with seven slots (140 mm × 180 mm × 130 mm) to achieve all the requirements for HSC. The maximum readout speed was 265k pixel/sec/CCDoutput and the readout noise was smaller than 3 electrons, including the clock jitter noise of 0.1 electrons. We concluded that our back-end readout electronics have sufficient performance for HSC.