Nanosecond Photodetectors
Using Filters and Optical Fiber • 15
Using Filters and Optical Fiber
New Focus offers accessories, sold separately, to attach
a 1"- diameter filter or an optical fiber to the detector.
Both accessories attach to the casing using the 1.04-32
threads located in the casing around the detector. Note
that the accessories are also compatible with two other
New Focus products, the Model 203X large-area pho-
toreceiver and the Model 215X femtowatt photore-
ceiver.
The Model 1280 1" filter holder allows you to mount a
1"- diameter optic in front of the photodetector. For
instance, you can mount a colored glass filter to
remove unwanted wavelengths or a neutral-density
filter to attenuate the optical power incident on the
photodetector. The Model 1280 has a plastic ring for
mounting a filter that is up to about 0.25" (6.4-mm)
thick. A thicker optic can be held in place using the
6-32 nylon-tipped set screw. Use a 1/16" or 1.5-mm
Allen key or ball-driver to adjust the set screw.
The Model 1281 FC fiber adapter allows you to connect
an FC connectorized fiber to the front of the photode-
tector. The coupling efficiency of light from an optical
fiber to the Model 1623 photodetector is typically 70%
or greater. The coupling efficiency is less than unity
because of the small detector size and small variations
in the mechanical position of the detector and the
fiber.
See Figure 6 for drawings of these two accessories. A
variety of fiber couplers, fiber collimators and pigtails
are also available from New Focus.
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