while reducing the risk of defective products reaching the consumer.
The alignment challenge and the prism-based solution
When multiple spectral bands are used, spatial alignment between channels becomes critical. Even small misalignments can lead to incorrect defect sizing or misclassification, particularly when acceptance thresholds are tight, and line speeds are high.
Prism-based multispectral cameras address this challenge at the optical level. In these cameras, incoming light from a single lens is spectrally separated by a prism block and directed onto multiple sensors. Because all spectral channels share the same optical path and viewpoint, pixel-level correspondence between RGB and NIR is inherently maintained.
This approach eliminates the need for external opto-mechanical alignment between cameras and ensures stable, repeatable registration over time, an important advantage in industrial sorting environments.
Additional benefits of the prismbased approach include:
• Compact camera design suitable for space-constrained machines
• Simultaneous exposure of all channels
• Robust performance at high line speeds
JAI’ s Fusion Series 3-CMOS multispectral prism camera providing simultaneous images of three different spectral bands in a single camera- a visible color channel from 400-670 nm, a near infrared( NIR) channel from 700- 800 nm, and a second NIR channel from 820-1000 nm.
Looking ahead: extending into SWIR
While RGB + NIR already enables powerful surface and subsurface inspection, many food-sorting applications benefit from access to short-wave infrared( SWIR) wavelengths, where absorption is directly linked to chemical composition.
SWIR wavelengths enable:
• More direct measurement of moisture and dehydration
• Improved correlation with sugar content( Brix)
• Detection of fat and oil content in nuts and meat
• Reliable discrimination of foreign materials such as stones, glass, and plastics
• Inspection through certain thin packaging films
Conclusion
As food sorting continues to evolve beyond surface inspection, prismbased multispectral cameras provide a robust and scalable foundation. By combining RGB and NIR today, and extending into SWIR in the near future, these systems enable more accurate classification, higher throughput, and simpler integration for machine builders and food producers alike.
For more information on prismbased multispectral cameras for optical food and fruit sorting, please visit www. jai. com.
JAI’ s Fusion Series 3-CMOS multispectral prism camera providing simultaneous images of three different spectral bands in a single camera- a visible color channel from 400-670 nm, a near infrared( NIR) channel from 700-800 nm, and a second NIR channel from 820-1000 nm.
FDPP- www. fdpp. co. uk 19