Model 7340 Monochromator Illuminator showing a lamp mount.
These popular monochromator illuminators match the output of numerous UV-IR sources to the input of most monochromators. They are useful for continuous broadband scanning because they hold two sources and scan from the UV (with a deuterium lamp) through the IR (with an infrared element), without breaking down your system. We offer two models - the 7340 which is a manually operated model, and the 7341 which is motorized.
Fig. 1 shows the simple optical path of the 7340 Illuminator (the 7341 has the same optical path). A square concave mirror collects the lamp radiation in its path, and creates a magnified image 2.5 inches (63.5 mm) in front of the illuminator housing. The magnification is approximately 1.8X. The mirror is coated with AlMgF2 for high reflectance over the 200 nm to 40 µm region. The mirror aperture is matched to the monochromator grating.
Each source is held in an independent lamp mount that has its own cables for the appropriate power source. A knob on the top of the 7340 Illuminator swings the mirror to a detented position facing the selected source. The 7341 Illuminator may be remotely operated via TTL signals, or via a switch on the top of the illuminator. Adjustments on the lamp mounts allow exact imaging onto the monochromator slit. Note: we recommend that you wait 30 minutes after you start the lamp for the illuminator to stabilize if you are doing critical measurements (reduces thermal drift).
The 73401 Adjustable Aperture Kit reduces the output angle of the 7340 to match slow F/# monochromators. It is made up of two right angle jaws mounted in front of the mirror. The jaws close over the mirror, reducing its usable area. You can also use the 73401 to improve spectral resolution when light is plentiful. Higher F/# leads to narrower line widths and reduced stray light.
These illuminators hold 16 different sources with the appropriate lamp mount. The drop in lamp mount design eliminates the need to open the housing, which allows you to change one lamp without disturbing the second. The mounts hold the source at the appropriate optical axis height. External adjustment controls let you tweak the position.
These illuminators are very efficient. The large mirror collects as much of the lamp radiation as the monochromator can accept. There are no other reflective or transmissive surfaces that can cause a loss of output. The exit port of the housing is a clear opening.Fig. 2 shows the output power from the 7340 with selected lamps. The smooth variation in power with wavelength from the quartz tungsten halogen lamp is ideal for broadband analytical work, while the higher power from the xenon lamp is necessary for some applications. The power is concentrated in an image ~1.8 times the size of the source.Fig. 3 shows the power through our Cornerstone 130 1/8 m Monochromator with 1.56 mm slits and a 350 nm blaze grating. The bandpass is 10 nm, so you might expect the values in Fig. 3 to be 10 times those in Fig. 2. The actual Fig. 3 values at any wavelength are less than 10X. Some power is lost because of monochromator efficiency and some due to slit vignetting. The 10 nm bandpass also smoothes the spectrum and lowers the peaks.
The lamp mounts that hold the lamps inside these illuminators include the necessary cables to connect to the appropriate power sources. The power source must be ordered separately.
These illuminators have four adjustable mounting feet for free standing use. The feet allow 0.63 inch (16 mm) height adjustment around a nominal optical height of 4.25 inches (108 mm). The output has a 1.5 Inch Series female flange. We recommend removing the feet and mounting the illuminator with the monochromator on a common baseplate. We offer kits that contain all the hardware (baseplate included) needed to mount both instruments on a common baseplate. To enclose the beam path, order the 71310 Light Shield.