Sutter Instrument Lambda 421, Operation Manual

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LAMBDA 421 OPERATION MANUAL – REV. 1.00N (20170623)
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1.2 General Description
CAPABLE OF COMBINING ANY LIGHT SOURCE
ANY SUITABLE WAVELENGTH (LED OR EXTERNAL FILTERED LIGHT SOURCE)
CAN BE PLACED IN ANY OF 4 POSITIONS WITHOUT CONCERN FOR THE ORDER
SELECTION AND BEAM REFLECTION USING SEMROCK-STR FILTERS
Figure 1-1. Lambda 421 indicators, controls, and connectors.
The Lambda 421 beam combiner is a new, patented, concept for combining separate light
sources with different spectra into a single common output beam. Each separate light source
is collimated before entering the optical path through a bandpass filter. The filters for each
light source also function as mirrors that reflect the collimated beams from the previous light
sources. In the diagram below the optical paths are outlined for each position including the
reflections that occur:
Traditionally, combining more than two light sources required the use of a dichroic ladder.
Dichroic mirrors, which switch from transmission to reflection at one point in the spectrum,
allow the combining of separate light sources, provided that those sources do not have
overlapping wavelengths. The downside of this approach is that light sources cannot be easily
changed.
Dichroic ladders also demand careful attention to the order in which the light sources are
introduced into the optical path, to avoid having the light blocked by the next dichroic in line.
Typically, additional bandpass filters must be added in front of each light source before the
dichroic, to select the desired range of wavelengths for each source. Each filter and dichroic
used in the ladder decreases the total light output of the system.