LP940 롱패스 필터(T>85%@950-1100nm, OD2@350-930nm)

Covert Surveillance & Security

This is the most common use. The 940nm wavelength is completely invisible to the human eye (unlike 850nm, which has a faint red glow). Cameras equipped with this filter can capture images in total darkness without alerting subjects.

Recommended Light Sources

To maximize the efficiency of an LP940 filter, you must use a light source that matches its transmission band (950nm-1100nm).

• 940nm IR LEDs:Why: These are the optimal match. They emit a narrow band of light centered at 940nm, which passes through the filter with >85% transmission.Benefit: They are "covert" (no visible red glow) and highly efficient for this specific filter.
• Broadband IR Illuminators:Why: Tungsten-halogen lamps or broad-spectrum IR arrays will work, but the filter will waste a significant portion of their energy (blocking everything below 930nm).Use Case: Only use these if you need a very high intensity that LEDs cannot provide, and heat generation is not a concern.
• 850nm LEDs (NOT Recommended):Why: The LP940 filter has an Optical Density of 2 (blocking 99% of light) up to 930nm. It would block the light from an 850nm LED, rendering the image black.

Moisture Detection

Water absorbs light significantly around the 940nm-970nm range. By using this filter, water or moisture appears dark or high-contrast against other materials, making it ideal for inspecting fruit quality, checking fill levels in opaque containers, or detecting leaks in fabrics.

Recommended Light Sources

• 970nm / 980nm High-Power LED

1. Why it works:Maximum Contrast: Water has a distinct absorption peak at 970nm. Illuminating at this specific wavelength causes water to appear darkest (absorbing the light) while other materials reflect it (appearing bright).Filter Compatibility: These wavelengths (970-980nm) are well above the 940nm cut-on of your filter, ensuring 100% transmission to the camera.
2. Form Factor:

- Backlight (for liquids): Use a flat LED backlight behind the container. The liquid will appear black against a bright white background.

- Diffuse Front Light (for fruit/fabrics): Use a ring light or bar light to illuminate the surface. Bruises (high water content) or wet spots will appear as dark patches.

• Broadband Halogen / Tungsten Light

1. Why: These emit a continuous spectrum including the 970nm-1100nm range.
2. Pros: Easy to source; covers all NIR absorption bands (including higher ones like 1450nm if the camera supports it).
3. Cons: Generates significant heat; less energy efficient than LEDs.