Package for optical filter device

An optical assembly includes a lens unit having a first lens and a second lens arranged on a common optical path with substantially coincident optical axes. Each lens has a transmission region through which light passes from a first side to a second side of the lens, and a first and a second table region on the periphery of the transmission region. The table regions are flat surfaces positioned on the first and second sides of each lens. An optical element holding tube is butt-coupled to the first table region of the first lens. An optical element, such as a filter, is supported on the first element holding tube. A second lens support tube holds the first lens and the second lens at opposite ends, with the first element holding tube therebetween. The first and second lenses and the optical element are passively aligned and then fixed in place with optical adhesive at the butt joints.