Tadashi Maruno

Single-photon-sensitive EBCCD with additional multiplication

A highly sensitive image sensor for single photon imaging has been developed. The sensor (referred as an intensified EBCCD here) contains a photocathode, a microchannel plate (MCP) and an electron-sensitive CCD in a vacuum tube. In response to incident photons, electrons emitted from the photocathode are multiplied once by the MCP, further by the CCD and read out. Either an image intensifier containing MCPs or an EBCCD containing an electron-sensitive CCD has sensitivity for single photon by itself, however, many intense white spot-noise appear on output image and degrade the image quality seriously at such high-gain operation. In the case of intensified EBCCD reported here, since both the MCP and the electron-sensitive CCD are used for electron multiplication, high gain for single photon detection is available in total at low gains of both devices. This operation reduces the noise drastically, and improves the image quality. We have developed the intensified EBCCD with a GaAsP photocathode for high quantum efficiency, and evaluated the performance. Comparing with conventional cameras, such as an EM-CCD and an image intensifier, the intensified EBCCD shows superior detection capability at especially low-light level, that is single photon imaging.

Newly improved very high sensitivity electron bombardment CCD sensor and camera

Electron Bombardment CCD sensor (EB-CCD) had originally developed for the low light imaging application and recently it has been coming to be used as an alternative to SIT tube camera and I-CCD camera. However, some of applications required higher sensitivity and higher dynamic range. In order to meet these expectations, we have been continuing the improvement of sensor such as higher gain and higher quantum efficiency. In this paper, we would like to introduce the new high gain sensor and new photo-cathode of GaAs and GaAsP, which realize the 30 to 50% quantum efficiency. And also we would like to show that how GaAs EB- CCD is sensitive based on the sensitivity comparison test between multi alkali photo-cathode image intensifier and new GaAs photo-cathode EB-CCD sensor.

EB-CCD life characteristics

Life characteristics of an EB-CCD incorporating a full frame transfer CCD have been evaluated. Applying -8kV to the photocathode, the accelerated life test corresponding to 3,500 hours of operation was carried out. As the result, there are no degradation of the photocathode sensitivity and the gain. However, an offset is increased linearly proportional to the operation period, including the upper and lower of the irradiated area. The increment after the life test is approximately 700 at 20 degree centigrade with a multi-pinned phase (MPP) operation. From the comparison between the MP and the non-MPP operation of the CCD, the original of the offset is concluded to be the increased dark current (DC) from the Si-SiO2 interface, which is damaged by the Bremsstrahlung x-ray. The DC slightly affects the signal as the offset when positive voltage to gate electrodes depletes the Si-SiO2 interface during the vertical transfer. The DC does not affect the signal at all with the MPP operation in the exposure time. The lifetime of the EB-CCD is calculated to be much longer than 10,000 hours, if the lifetime is defined by the period that the DC fulfills the half of the full well capacity.

Comparison of CMOS and EMCCD Cameras for Computational Imaging with Application to Super-resolution Localization Microscopy

Gen II scientific CMOS (sCMOS) cameras provide higher signal to noise ratios than EM-CCD cameras for most fluorescence microscopy applications, including single molecule imaging. We discuss implications for computational imaging.

Characteristics of a TV-rate electron bombardment CCD camera

We have developed the two kinds of Electron Bombardment CCD Camera employing a full frame transfer type and a frame transfer type electron bombardment sensor made by Hamamatsu Photonics. Especially in order to make a camera practicable for various application, we improve the image resolution and tried to measure the life of frame transfer type sensor. With regard to the resolution, there are many factors which degrades the resolution. This time, we reduced the gap length between a photo-cathode and a CCD to 60 percent of original one, hence, the sensor had greater resolution than 450 TV. Furthermore life of sensor is getting longer, because of the MPP CCD structure. C7162-20 Frame transfer Electron Bombardment CCD camera performs as a standard TV rate camera. From the point of camera performance, it can be replaced the SIT tube camera and I-CCD camera. In order to prove this fact, camera was compared with GEN 4 I-CCD camera which uses a small aperture MCP and a Blue-GaAs photo- cathode coupled to the CCD through optical fiber, and we show the result of comparison.

Electron bombardment CCD camera

Two kinds of electron bombardment CCD (EB-CCD) camera are newly developed, employing an EB-CCD sensor made by Hamamatsu Photonics. The slow scan cooled CCD camera installs the full frame transfer type EB-CCD sensor with 512 X 512 pixel format and standard video rate camera installs the frame transfer type EB-CCD sensor with 658 X 490 pixel format. For slow scan camera, EB-CCD sensor is cooled down to -25 degree C to realize high sensitivity utilizing long exposure time and very low noise performance. And instead of mechanical shutter, high speed electrical gated function is installed in this camera. Standard video rate camera has a function of recursive filter and auto background subtraction as a standard in order to get high quality image. Furthermore, camera can select both inter- laced scan and progressive scan readout mode. These cameras have been compared with the other high sensitive camera like SIT camera, photon counting camera and I-CCD camera which results in proving that these EB-CCD camera are suitable and ideal.