Sutter Instrument Lambda 421, Operation Manual

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LAMBDA 421 OPERATION MANUAL – REV. 1.00N (20170623)
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Figure 1-2. Stages of pass-through and reflection from each input light source.
The Lambda 421 was designed to keep the size of the beam combiner small, and the optical
path short and efficient. Thin-film bandpass filters, such as Semrock’s STR, reflect greater
than 90% of out-of-band light. If the band pass of each light source does not overlap, it is
possible to use the filters for both attenuation and reflection the light from the other sources.
By arranging the filters and sources into a pentagon, we were able to combine four light
sources, in a compact design, with lower losses than previously achievable. As an added
benefit, the last position in the optical train does not require any filter, since no other input
reflects from that position. This input can be used with any sort of light source as long as you
are aware of the possible losses if there are filters in use that overlap this light source. The
fifth side of the pentagon becomes the output for the combined sources.
The filters are easily exchangeable and are installed on small sliders inside the core of the
pentagon. Filters and associated light sources can be arranged in any order around the
pentagon.
In the diagram below the position number of each light source is labeled based on the
number of total reflections.
Figure 1-3. Lambda 421 combined output based on the pass-through and reflection of each input light source.