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Optical Filter Orientation

Optical Filter Orientation

One of the most common questions regarding optical filters is in regards to the filter orientation, specifically: which side of the filter should be facing the input light source? For any application, filters should be oriented such that the coated surface faces the light source.

On the opposing surface to the coated surface, an anti-reflective (AR) coating is applied to improve transmission in the desired wavelength range, while adding extended spectral blocking outside of the desired range.

For extremely sensitive applications, proper orientation and directionality should be maintained. However, TECHSPEC® Filters will perform to specification when oriented in either direction.

Specifying Edmund Optics® Filters

  • All mounted TECHSPEC® Optical Filters have an arrow on the side of the mount that points to the filter-coated surface for quick reference.
  • All unmounted TECHSPEC® Optical Filters have a small pencil or ink mark on the edge outside of the clear aperture to indicate the filter-coated surface.
Filter oriented such that arrow points to filter coated surface S1. Anti-reflective (AR) coating is applied to S2.
Figure 1: Filter oriented such that arrow points to filter coated surface S1. Anti-reflective (AR) coating is applied to S2.

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Range of bandwidth options, from very narrow bandwidths for laser line filters to broad bandwidths optimized for fluorescence filters.

Offered with coating options for the UV, visible, or IR spectrum. Available in a range of optical densities with superior blocking.

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