Princeton NFC-446-040 User Manual

15 Discovery Way, Acton, MA 01720

Phone: [phone], Fax: [phone]

Web Site:

www.piacton.com

Operating Instructions

for

NFC-446-040

Raman Notch Filter

Ver 2.0

Supplemental Instructions

Model NFC-446-040

Raman Notch Filter Assembly

Description:

The ARC Model NFC-446-040 is a filter chamber
designed to permit use of Raman notch filters with
ARC monochromators and spectrographs. It is
designed primarily to collect the output of fiber
optics, however it may be used with other sources
of Raman scatter (e.g., focused sample image or
direct collection of scatter from a sample
positioned close to the NFC-446040).

The standard NFC-446-040 includes a lens
chamber with sample holder designed to accept

1.5 inch diameter filters. Other sample holders are
available on a custom order basis. Filters can be
rotated up to 10° by an external micrometer in
order to tilt-tune the rejection band of the filter.

Principle of Operation: The NFC-446-040 is
designed to provide a collimated beam for
operation with notch (or cut-off) filters. The first
lens collects and collimates the beam through the
notch filter. The second lens collects the collimated
beam and focuses it to the entrance slit of the
monochromator or spectrograph. The light is then
dispersed to a detection system.

Notch filters are designed to significantly reduce (or block) the amount of laser light
reaching the monochromator or spectrograph, while transmitting the desired Raman
scatter. This permits efficient detection of the Raman scatter by the system without
requiring a double or triple monochromator. The integrated tilt adjustment capabilities
of the NFC-446-040 enable fine tuning of the notch filters to achieve the best
combination of laser light blocking and Raman scatter transmission.

Figure 1: NFC-446-040 Layout (Top View)

Mounting the NFC-446-040 to Acton Series Monochromators or Spectrographs:

Use the illustration above for reference when mounting the NFC-446-040 to ARC
monochromators or spectrographs.

1. Unpack the NFC-446-040 Raman Notch Filter Chamber.

2. Remove the cover of the NFC-446-040.

3. Set the components on a stable, flat working surface. Position the NFC-446-040

against the ENTRANCE SLIT of the Acton Series monochromator or spectrograph
as shown in the illustration above. Align the mounting holes of the NFC-446-040
with the tapped holes in the slit assembly.

4. Insert the two (2) 8-32 screws provided through the mounting holes and into the

tapped holes of the slit assembly. Tighten to secure the NFC-446-040 to the
entrance slit.

5. The NFC-446-040 includes a support post to help stabilize the system. This post

should rest flat on the working surface, and should not exert stress on the system.
The NFC-446-040 is now mounted to the Acton Series monochromator or
spectrograph.

Mounting a Filter inside the NFC-446-040:

The standard filter holder inside the NFC-446-040 accepts 1.5” (38.1mm) diameter
filters. Use the following procedure to mount filters:

1. If not already completed, mount the

NFC-446-040 to the monochromator or
spectrograph.

2. Remove the NFC-446-040 access cover.

3. Locate the filter holder between the lenses.

4. Slide the notch filter into the holder and

secure it in position with the set-screw
(located on top of the holder).

5. Replace the access cover.

Optimizing the NFC-446-040 for Best Performance:

Lens Aperture Ratio:

Under normal operating conditions with Acton Series monochromators and
spectrographs, use the following lens aperture settings inside the NFC-446-040:

SP-150, SP-275, or SP-300i: Set both lenses to an aperture of 4 or smaller.

SP-500 or SP-500i: Set both lenses to an aperture of 6.5 or smaller.

SP-750: Set both lenses to an aperture of 9.7 or smaller.

Note: When using fiber optic input, especially when the fiber size or configuration of
fibers is tall (e.g., a column of fibers), we recommend setting the aperture of the lens
closest to the fiber at 1.8. This will permit efficient collection of the fiber output and
will reduce possible vignetting of the light.

Note: It is possible to adjust the lens apertures of the NFC-446-040 to optimize
system performance. Reducing the aperture of the lenses, for example, will
improve the overall image quality of the system.

Lens Focus:

The NFC-446-040 is optimized for best performance when the light source image is
in sharp focus on the monochromator or spectrograph entrance slit, and both
lenses are set to the same focus position. This can be accomplished using the
following procedure:

1. Assure that the NFC-446-040 is correctly mounted to the monochromator or

spectrograph.

2. Mount the detection system to the monochromator or spectrograph. Assure that

the detection system is operating.

3. Use a light source with line spectrum output, such as a mercury pen-ray lamp.

4. Set the monochromator or spectrograph to a central wavelength of 435.8nm if

using a mercury source, or the corresponding wavelength to match your light
source output if it is not mercury. If no line source is available, use a white light
source and set the monochromator or spectrograph to a central wavelength of

0.0 nm.

5. Operate the system and continuously monitor for intensity. Slowly adjust the

lenses until highest intensity is achieved, and both lenses are set to the same
focus position.

6. When operating the NFC-446-040 with multiple light source inputs (a multi-leg

fiber optic bundle, for example), an imaging spectrograph, and a CCD detection
system, we recommend operating the detection system in an imaging mode and
adjusting the lenses until best image quality is achieved.