Detecting Hair Contamination in Food with SWIR Image Sensor

Application: Food manufacturing industry

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Solution Proposal
Detecting Hair Contamination in Food with SWIR Image Sensor

Introduction

In the food manufacturing industry, strict hygiene control is required to ensure consumer safety and quality. Particularly during the manufacturing of processed foods, contamination by hair and other impurities is a serious problem. Any hygiene failure can cause consumers to lose trust in a product.
Contaminant detection technology has been introduced in recent years to the food industry, and short wavelength infrared (SWIR) image sensors are able to detect hair contamination in food with high accuracy. These sensors are suited to capturing the characteristics of hair and are effective for non-contact high-accuracy identification of contaminants that are difficult to detect under visible light.
The application of Sony’s SWIR image sensors to the detection of hair contamination is introduced below using actual cases of captured images.

Challenges

Detecting hair contaminants using conventional methods alone during the manufacturing of processed foods may be inadequate. Visual inspection or standard sensors may miss fine hair and are therefore insufficient to ensure product quality. In addition, as the speed and production volumes of manufacturing lines continue to increase, prompt and accurate detection is required.

Solution

Sony’s SWIR image sensors are devices that capture light in the visible to short wavelength infrared (SWIR) band.
Hair characteristically reflects SWIR wavelength light well and is captured brightly by an SWIR camera. Meanwhile, foods with a high moisture content absorb 1450 nm wavelength light and are captured as dark or black objects by an SWIR camera. This contrast between bright hair and dark food enables clear identification. In addition, Sony’s SWIR image sensors are equipped with its proprietary technology SenSWIR, which delivers both high sensitivity and high resolution, meaning even fine hair can be clearly identified.

[Cases of Captured Images]

Below are comparisons of images captured using a visible light camera and a short wavelength infrared (SWIR) camera. Equipped with a 1450 nm band-pass filter, the SWIR camera captures light with a wavelength that is easily absorbed by the moisture in foods.

Example of detection of hair on raisins

Move the slider to check the difference.

Image captured using a color camera in “Example of detection of hair on raisins”

Left: Captured using a standard color camera
Right: Captured using an SWIR camera (1450 nm)

These are examples of captured images when two strands of hair are mixed in with many raisins (of a similar color). In the image captured using a color camera, the hairs blend in with the raisins and are not clearly visible. However, in the image captured using the SWIR camera, the hairs clearly appear white against the dark raisins, enabling their presence to be confirmed.

Example of detection of hair in a bento lunchbox

Move the slider to check the difference.

Image captured using a color camera in “Example of detection of hair in a bento lunchbox”

Left: Captured using a standard color camera
Right: Captured using an SWIR camera (1450 nm)

In the image captured using a color camera, the hairs blend in with the food and are not identifiable but, in the image captured using an SWIR camera, the hairs brightly reflect the SWIR wavelength band to appear as white objects. In addition, the moisture in the food absorbs light with a wavelength around 1450 nm, causing the food to be captured as a black object. The resulting contrast enables the hairs to be easily detected.

Example of detection of hair on a croquette

Move the slider to check the difference.

Image captured using a color camera in “Example of detection of hair on a croquette”

Left: Captured using a standard color camera
Right: Captured using an SWIR camera (1450 nm)

Hairs blend into the croquette and are not clearly visible in the image captured using a color camera. However, they are brightly reflected and captured as white objects in the SWIR wavelength when using an SWIR camera, clearly standing out from the dark surface of the croquette.

[Prospects]

This page shows three cases of processed foods to present actual examples of how SWIR image sensors can detect hair. Using a wavelength of 1450 nm enables hair to be detected in various types of other foods in addition to the foods introduced here.
One area where SWIR image sensors excel is the ability to utilize their characteristics to identify hair, which is difficult to do using visible light, with high accuracy. The application of this technology to various products in the food industry is expected to improve hygiene control in manufacturing processes, thus contributing to the provision of safe and reliable foods for consumers.

If you are interested in SWIR image sensors or their application, please contact us using our inquiry form.
You can download a list of cameras with SWIR image sensors here.

What's SWIR？

Generally, light with a wavelength of 400 nm to 780 nm is referred to as visible light, and light with a wavelength of 780 nm to 106 nm as infrared light. The wavelength band of SWIR is from 900 nm to 2,500 nm, which is the region of infrared light closest to visible light. Image sensors equipped with SenSWIR technology are capable of broad imaging over the range of 400 nm - 1,700 nm, including visible light as well as SWIR light.