Narrow-line holographic filters that can include a plurality of lines and
that can be structured to provide a large aperture device. Materials that
can be used to construct filters include glasses, photorefractive
crystals such as lithium niobate and photorefractive thick polymers. The
filters are fabricated by assembling a plurality of elements having the
same one or more narrow line holographic filter patterns written thereon,
in mutual orientation such that each element has a surface defined by a
length and a width adjacent a corresponding surface of a neighboring
element, and has a surface defined by a thickness and one of a length and
a width accessible to impinging illumination. Filters exhibiting a
plurality of characteristic narrow lines, and having arbitrarily large
apertures can be fabricated. Methods of fabricating and using the filters
are described.