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Author Topic: DCS Network Cameras - Improving Night Mode with an External IR Illuminator  (Read 9227 times)

JavaLawyer

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D-Link Cloud camera owners can extend the visible distance of their camera Night Mode (i.e. night vision) using an external IR illuminator. The IR illuminator refers to the red LEDs that engage when a D-Link camera is in Night Mode. The integrated IR illuminators that ship with D-Link cameras have a limited range and are unable to penetrate any appreciable distance through obstructions such as windows.

Monitoring Outside Activity through a Window at Night

When a D-Link network camera is facing a window with the intent of monitoring outdoor activity at night, the integrated IR illuminators (i.e. red LEDs) typically reflect off the window back at the camera lens. An outdoor external IR illuminator located outside near the area that needs to be monitored can enable a D-Link Cloud camera to remain indoors (pointed out a window) in Night Mode and clearly see outdoor activity.

If a D-Link network camera is pointed out a window with Night Mode enabled, the integrated IR illuminator (red LEDs) must either be disabled or covered to prevent reflection off the window. Some newer D-Link network cameras may contain an option to enable night mode while disabling the integrated IR illuminator. For most D-Link network camera consumer models, the IR illuminators must be physically covered (e.g. with electrical tape) to prevent reflection.

What IR Illuminator Bulb Wavelength Should I Purchase?

850 nm (850 nanometer wavelength) is the industry standard wavelength used for IR Illuminators. The light generated from a 850 nm bulb is invisible to the human eye, but the bulb itself generates the distinctive red glow that is visible to the human eye if viewed directly (e.g. red LEDs on many cameras with Night Mode).

940 nm (940 nanometer wavelength) is completely invisible to the human eye, and does not generate the red glow visible from a typical 850 nm light source. The covertness of the 940 nm wavelength bulb makes this light source better suited for stealthy applications.

When comparing 850 nm and 940 nm bulbs of the same power, 940 nm bulbs have a shorter range when compared to 850 nm. A more powerful 940 nm light source or more narrowly focused 940 nm field of view can be used to compensate for this shortfall.

Distance versus Viewing Angle

Since a particular IR illuminator will generate a fixed amount of light, how that light is distributed will impact performance.  Focusing the light in a relatively tight beam with a small field of view will maximize distance (similar to a flashlight), but reduce the viewing area/angle. Conversely, allowing the light to disburse over a wide area (i.e. large viewing angle), will maximize the field of view (similar to a table lamp), while reducing effective distance. The more powerful the light source, the greater these variables can be compensated for.

A greater range and narrow field of view would be appropriate for monitoring a long narrow hallway, while a shorter range and wider field of view would be ideal for monitoring a square-shaped room.

Additional Resources

Disclaimer

The author of this post does not have access to the bulb wavelength specifications used for the D-Link network camera series, so the effectiveness of the solutions presented here is not guaranteed.
« Last Edit: December 18, 2014, 04:02:08 PM by JavaLawyer »
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