PROCEEDINGS ARTICLE | February 10, 2009
Proc. SPIE. 7126, 28th International Congress on High-Speed Imaging and Photonics
KEYWORDS: Beam splitters, Microlens array, Cameras, Image processing, Video, Field programmable gate arrays, CCD cameras, Signal processing, Microlens, Charge-coupled devices
We developed an ultrahigh-speed color video camera that operates at 1,000,000 fps (frames per second) and had capacity to store 288 frame memories.
In 2005, we developed an ultrahigh-speed, high-sensitivity portable color camera with a 300,000-pixel single CCD (ISIS-V4: In-situ Storage Image Sensor, Version 4). Its ultrahigh-speed shooting capability of 1,000,000 fps was made possible by directly connecting CCD storages, which record video images, to the photodiodes of individual pixels. The number of consecutive frames was 144. However, longer capture times were demanded when the camera was used during imaging experiments and for some television programs.
To increase ultrahigh-speed capture times, we used a beam splitter and two ultrahigh-speed 300,000-pixel CCDs. The beam splitter was placed behind the pick up lens. One CCD was located at each of the two outputs of the beam splitter. The CCD driving unit was developed to separately drive two CCDs, and the recording period of the two CCDs was sequentially switched. This increased the recording capacity to 288 images, an increase of a factor of two over that of conventional ultrahigh-speed camera.
A problem with the camera was that the incident light on each CCD was reduced by a factor of two by using the beam splitter. To improve the light sensitivity, we developed a microlens array for use with the ultrahigh-speed CCDs. We simulated the operation of the microlens array in order to optimize its shape and then fabricated it using stamping technology. Using this microlens increased the light sensitivity of the CCDs by an approximate factor of two.
By using a beam splitter in conjunction with the microlens array, it was possible to make an ultrahigh-speed color video camera that has 288 frame memories but without decreasing the camera's light sensitivity.
