JAI's Unique Solution for High Dynamic Range Imaging

Jai's latest addition to the advanced tier of its C3 camera suite features a unique, prism-based 2CCD camera, incorporating two monochrome CCD sensors configured for extremely high dynamic range. The prism-based design enables a single optical path to be split across both CCDs while maintaining alignment to within one-quarter pixel. This means the AD-081CL high-dynamic camera gives users the ability to capture two monochrome images of the same scene simultaneously, each with radically different exposure settings (shutter and/or gain) to produce a high total dynamic range. The two standard monochrome progressive scan sensors are mounted on a custom-designed optical prism which enables the camera to capture two channels of of pixel correlated video at 30 fps.

What are the benefits of this prism-based camera?
Aligning the two prism-mounted sensors to within one-quarter pixel accuracy enables the AD-081CL's high-dynamic range capability to be applied to inspection tasks regardless of whether or not the objects are in motion: a feat that cannot be replicated using two separate cameras or with multiple exposures with a single CCD. An added benefit of a one-camera solution is that it is priced considerably lower than a two-camera system, particularly when optics, illumination, image acquisition and other related items are considered.

How does the camera operate?
The shutter speed and/or gain for each channel of the AD-081CL can be calibrated independently, one channel capturing the details in the brighter areas while the second capturing the identical image, but with an emphasis on the details in the darker areas. These two images can then be analysed separately or post-processed and recombined to produce orders of magnitude higher dynamic range of standard CCD cameras. This method avoids the noise, shutter, and compression issues typically associated with CMOS-based logarithmic high-dynamic-range cameras.

An illustration of this technique can be seen in the following images captured by Jai's AD-081 camera.
The incident light coming from the light globe makes it impossible to examine both the bright and the dark areas of this scene in a single exposure. Instead, two exposures are used as shown in Figure 1. The left half of the image shows what the image looks like when captured with a slow shutter speed resulting in the capturing of detail in the surrounding areas while letting the brightest parts of the scene saturate. The right half of the image shows the result of a much faster shutter speed, enabling details to be seen in the brightest portions of the image while rendering much of the surrounding area as nearly black. When "fused", as shown in Figure 2, the composite image is able to span the full dynamic range of the scene.

	Figure 1 - Bracketing the exposure	Figure 2 - Fused HDR image

The Jai AD-081CL is equipped with two configurable Camera Link outputs providing users with a choice of a single-cable operation or using separate cables for each channel. Other features include particle scanning and vertical binning capabilities as well as analogue video output to support auto-iris lenses.

What are some typical applications for the AD-081CL camera?
Typical HDR application for the AD-081CL include inspection tasks where incident light or bright reflections are present, such as LED inspection, welding, in-situ solar panel inspection and various types of lighting or glass inspections.

The camera is also ideal for a wide range of automotive applications, microscopy or high-end surveillance uses.