JAI multi-sensor prism cameras provide a range of colour advantages over single sensor cameras

Achieving true colour in terms of low inter-channel crosstalk, colour differentiation, vibrant hues, accurate contrast and good image depth for every channel can be a difficult outcome to reach. A development style that camera manufacturer JAI have pursued so to maximise their capacity to reach this outcome is through producing a large range of multi-sensor prism cameras in both area scan and line scan variants. Prism cameras separate incoming light in a way that produces much higher quality images that single sensor cameras. By contrast, cameras based on Bayer Mosaic single sensors rely on interpolation routines and so produce images that lack resolution and colour fidelity of multi-sensor cameras.

The prism block mounted at the entry of the camera and behind the lens is made up of multiple prisms, each with a hard dichroic coating that separates the three RGB bands and illuminates each sensor with a single band. The blue band (shortest wavelength) is reflected within the prism in one direction, followed by the red band in the opposite direction with the green passing directly through the prism. This design method ensures minimum loss of signal strength. Every pixel on each sensor is illuminated by a single band. The prism also has an IR cut-off filter on its front face to eliminate NIR wavelengths which would otherwise provide an artefact signal on the blue and green sensors. In contrast, a single sensor Bayer RGB camera, has filters on each individual pixel that differ. Each cluster of full pixels has a repeating pattern of filters over the full sensor. One pixel with red, one pixel with blue and two pixels with green filters.

While a Bayer Mosaic filter sensor allows a full RGB image to be captured with a single sensor there is a price to pay in image quality.
• A single pixel sensor's are single colour to generate the other two colours on that pixel the camera uses an interpolative mathematical technique and generates a colour value based on adjacent pixels of that colour. So two colours in that pixel are an approximation. This is most evident in an image where there is a sharp colour change and is visible in the image as a zipper effect where colours on that edge are clearly incorrect. There are numerous Bayer demosaicing algorithms, some better than others but all have advantages and disadvantages and none produce a perfect image.
• Crosstalk - Photons hitting the sensor at an angle will hit a pixel and sometimes penetrate through to the adjacent pixel resulting in a stronger signal of the adjacent pixel and a weaker signal of the pixel it hit.
•The blue filter wavelengths overlap with the green filter wavelengths, which overlap with the red filter wavelengths which causes further degredation of the colour reproduction.

Prism cameras avoid almost all of the above problems associated with single sensor Bayer Mosaic cameras. One disadvantage however of prism cameras is that the intensity of light reaching the sensor is reduced because the light has been split by the prism. This results in lower sensitivity and so more light or longer exposure times are required.

By using multi-sensor prism based sensor designs, JAI's prism cameras produce better colour images compared to that of standard single sensor cameras. In order to achieve pixel-to-pixel correlation in all bands the design and manufacture of prism based cameras requires extreme mechanical precision that can only be achieved with customized very high performance automation. JAI has invested heavily for many years in this technology and is a clear leader in producing prism cameras for the machine vision industry. There are few other manufacturers that have committed and can produce prism cameras. JAI's clever design allows users access to outstanding results when it comes to image analysis and processing in colour for machine vision applications.

The JAI Fusion series of cameras includes the Flusion Flex-Eye series which provide the ability to customize the wavelength bands of each sensor. The camera does not necessarily need to produce an RGB colour image. If your application requires very specific wavelengths and bands the Flex-Eye series maybe a great solution.

The JAI fusion series is a consists of eight high-end multi-sensor prism cameras that offer two or three colour and/or NIR bands with precise pixel-to-pixel alignment. To ensure a consistent signal-to-noise ratio the JAI fusion series has the ability to adjust the exposure time of each channel.

The Fusion cameras are ideal for machine vision, industrial inspection, medical imaging and more.

Features:
• Standard or custom-designed configurations with up to three wavebands
• Up to 3.2 megapixels per channel.
• Custom waveband specifications from 25 nm located in the 405-1000 nm range (visible - NIR).
• 10 GigE multi-stream interface for simultaneous high-speed capture and output.

The Apex series of cameras provides precise RGB raw image data which is perfect for colour machine vision applications across a range of industries like pharmaceutical, electronics, printing/packaging and imaging in microscopy and medical diagnostics equipment.

The 3-sensor imaging technique used in the Apex series allows more accurate per-pixel colour values than what is possible with the Bayer Mosaic technique. The cameras also offer higher spatial resolution, enabling more accurate edge detection and the ability to resolve smaller details.

The CMOS cameras in the Apex Series deliver significant user advantages in terms of resolution, speed and colour pre-processing functions without being a budget-breaker.

Features:
• The Apex series comprises 10 different cameras with resolutions of 1.6 or 3.2 megapixels.
• The latest AP-3200T models features Sony Pregius IMX265 or IMX252 sensors.
• The AP-1600T models features Sony Pregius IMX273.
• All models feature on-board colour space conversion including: RGB to HSI, RGB to CIE XYZ and RGB to sRGB/Adobe RGB.
• Analog gain and exposure time can be set independently for the RGB channels allowing for better SNR conditions.