Development of ultrahigh-speed CCD with maximum frame rate of 2 million frames per second

Abstract

We developed a 300,000-pixel ultrahigh-speed CCD with a maximum frame rate of 2,000,000 frames per second. The shooting speed of the CCD was possible by directly connecting CCD memories, which record video images, to the photodiodes of individual pixels. The simultaneous parallel recording operation of all pixels results in the ultimate frame rate. We analyzed a voltage wave pattern in the equivalent circuit model of the ultrahigh-speed CCD by using a SPICE simulator to estimate the maximum frame rate. The pixel area was consisted of 410 and 720 pixels in the vertical and horizontal and divided into 8 blocks for parallel driving. An equivalent circuit of one block was constructed from an RC circuit with 410 × 90 pixels. The voltage wave pattern at the final stage of an equivalent circuit was calculated when a square wave pulse was input. Results showed that the square wave pulse became blunt when the driving speed was increased. After estimation, we designed the layout of the new ultrahigh-speed CCD V6 and fabricated the device. Results of an image capturing experiment indicated a saturation signal level of 100% that was maintained up to 300,000 frames per second. A saturation signal level of 50% was observed in 1,000,000 frames per second and of 13% in 2,000,000 frames per second. We showed that the maximum frame rate is dependent on a drop of the saturation signal level resulting from the driving voltage wave pattern becoming blunt.