Project Name: Imaging Experiment on Same-Color Oil and Water Using SWIR1503B10G SWIR Camera
Test Date: May 2026
I. Test Objective
To verify the imaging capability of the Attostek SWIR1503B10G SWIR camera in distinguishing same-color oil and water, to evaluate the feasibility of SWIR technology for liquid identification and oil-water separation detection, and to compare the results with those of a visible-light camera.
II. Application Background and Principle
2.1 Application Background
In industrial production, food processing, chemical storage, and environmental monitoring, there is often a need to distinguish between oil and water. For example, detecting whether moisture has mixed into pipelines, monitoring water accumulation layers in oil tanks, and assessing the effectiveness of oil-water separation in wastewater treatment. When oil and water are the same color, the naked eye and visible-light cameras cannot directly distinguish them. Short-wave infrared imaging technology, based on the different absorption characteristics of liquid molecules to infrared light, can effectively solve this problem.
2.2 Detection Principle
Water exhibits strong absorption of infrared light, particularly at the 1450 nm wavelength, resulting in weak reflected signals and appearing as dark areas in the image. Oil, on the other hand, has no strong absorption characteristics in this band, and its reflected signals are relatively stronger. Therefore, oil and water can be quickly and accurately identified by capturing images with an infrared camera. In addition, external infrared fill light or infrared filters can be used to enhance the difference in reflection intensity between oil and water captured by the camera.
2.3 Camera Performance Requirements
- High signal-to-noise ratio (SNR)
- High quantum efficiency (QE)
Specifications of the SWIR1503B10G camera used in this report:
- Maximum SNR: 62.98 dB
- Quantum efficiency at 1300 nm wavelength: approximately 75%
III. Test Equipment and Parameters
| Equipment/Component | Model/Specification |
|---|---|
| SWIR Camera | Attostek SWIR1503B10G |
| Visible-Light Camera | Attostek VIS028CU3.2-NC |
| Light Source | 1300 nm infrared light source |
| Optical Filter | 1300 nm infrared filter |
| Test Samples | Same-color oil and water |
| Environmental Conditions | Indoor environment, no special light source except experimental fill light, temperature 25°C |
IV. Test Procedure
- Place equal amounts of oil and water into two identical plastic containers respectively. Fix the SWIR1503B10G camera and adjust the positions of the oil and water so that they are centered in the lens field of view.
- Manually adjust the camera focus and aperture to obtain a clear image.
- Select an appropriate exposure time (manual or automatic mode).
- Capture images with the SWIR1503B10G camera under the following conditions: no filter or fill light, with 1300 nm fill light, with 1300 nm filter, and with both 1300 nm filter and fill light.
- Capture a reference image using a visible-light camera (VIS028CU3.2-NC) from the same position.
V. Test Results
5.1 Image Observation Results
- Visible-light camera capture: Both oil and water are colorless transparent liquids with identical appearance. In the plastic containers, the visible-light image can hardly distinguish between the two, with no difference in brightness or color.
- SWIR1503B10G direct capture: The water area appears dark with very low grayscale values, while the oil area appears bright white. The grayscale contrast between the two is very significant and can be easily distinguished.
- With 1300 nm fill light: Overall image brightness is improved, and the contrast between bright and dark areas is further enhanced.
- With 1300 nm filter: Light outside the 1300 nm wavelength is filtered out, enhancing the contrast between bright and dark areas.
- With filter + fill light: The best imaging quality is achieved, with the water area appearing dark gray and the oil area appearing bright white, providing the clearest distinction between the two.
5.2 Quantitative Contrast Analysis
To quantitatively evaluate the discriminative capability, contrast was calculated using the following formula:
Contrast = (I_max − I_min) / Gray Scale Range
where I_max and I_min are the average grayscale values of oil and water respectively, and the gray scale range is 255 for 8-bit images.
| Capture Condition | Water Grayscale Value | Oil Grayscale Value | Calculated Contrast |
|---|---|---|---|
| SWIR1503B10G direct capture | 65.7 | 24.6 | 0.16 |
| With 1300 nm fill light | 89.5 | 27.9 | 0.24 |
| With 1300 nm filter | 92.8 | 49.3 | 0.17 |
| With 1300 nm filter and fill light | 114.6 | 48.0 | 0.26 |
VI. Result Analysis
- Function verification: The SWIR1503B10G SWIR camera can effectively distinguish same-color oil and water, with water appearing as dark areas and oil as bright areas, showing clear contrast between light and dark.
- Phenomenon summary: Compared with direct SWIR camera capture, the combination of 1300 nm filter and fill light provides the highest contrast, increasing it to 0.26, with the best imaging quality and the highest recognition reliability.
- Performance: The camera has high signal-to-noise ratio, a clean image background, and clear contrast between oil and water, meeting the requirements of this application scenario.
VII. Conclusion
The Attostek SWIR1503B10G SWIR camera can efficiently distinguish between oil and water, which have different chemical compositions, even when their colors are completely identical. Under 1300 nm filter and fill light, the contrast between oil and water is the highest. With its high SNR and high quantum efficiency, this camera can be applied in areas such as oil-water interface detection, pipeline leak monitoring, tank water accumulation alarming, and liquid inspection in food processing, offering a non-contact, real-time, low-cost optical inspection solution. In practical applications, it is recommended to use a 1300 nm filter and a fill light of the same band to achieve the best imaging contrast.
