The 9490 monochromator, Sciencetech's second largest monochromator with 1m focal length, can achieve resolutions as high as 0.017 nm in its standard "single pass" configuration (with a 1200 l/mm grating). Up to twice as high is possible in "double pass" configuration, which doubles the effective focal length to 2m. Model 9490SD lets the operator switch between these two modes.

The standard version uses 84 x 84 mm gratings for an aperture of f/9.7, and a high throughput “Fast” version is available using 102 x 102 mm gratings for an aperture of f/7.4. Both versions accommodate one grating at a time on a removable, kinematic mount. Users can manually swap one grating for another without losing alignment. An optional, motorized, 4-grating turret is available for automatic grating selection without opening the cover. Gratings are sold separately. The 9490SD has a flat field output allowing it to operate as a spectrograph using a linear array, multi-channel detector to capture the entire output spectrum at once. Sciencetech provides a selection of 1" wide CCD and photo-diode linear array detectors mounted on a multi-axis adjustable focusing platform for use with the 9490SD.

Double Pass Configuration In Double Pass configuration, the light beam essentially repeats the Czerny-Turner optical path twice inside the monochromator before exiting the output port. The first pass is identical to the standard single pass configuration, except only the top half of the entrance slit is used. The output from the first pass, instead of being focused to the output port, is re-directed through a special return mirror system through an intermediate slit and back to the input mirror for a second pass. After the second pass, the light beam focuses at the output port, passing above the special return mirror system. Please note that light beam height is only half that for the single pass configuration due to the shared vertical placement of the special return mirror system and output port. The intermediate slit in the return mirror system minimizes stray light. This intermediate slit width is manually adjustable, but is generally set to the maximum width allowable for the application. 

 High Resolution Slits One bilaterally adjustable high resolution slit for the input port is standard. The slit is manually adjustable with a micrometer thumbwheel from 0 mm-6 mm width. The maximum slit height is 38 mm, but can be reduced through an optional height adjustable stepwise cover. A computer controlled, motorized version of the high resolution, bilaterally adjustable slit is available as an option (SS83-HR).

 An additional slit is required for the output port if the 9490 is used as a monochromator with a single-channel detector mounted at the output port. An additional slit is not required if the 9490SD is used as a spectrograph with a multi-channel detector mounted at the output port.

 Computer Interface All Sciencetech computer controlled monochromators and motorized accessories such as motorized slits, dual port flipping mirrors, and filter-wheels are connected to the computer via serial (RS-232) or optional USB interface. For serial interface, Sciencetech has developed a proprietary addressing system such that one serial port can control up to 4 motorized devices. A Sciencetech RS-232 four-way splitter is required if more than one RS-232 motorized device is used. Each computer controlled motorized device requires its own Sciencetech MD-100 universal stepper motor controller. The 9490SD has at least one MD-100, built-in to control the motorized grating.

Control Software An Active-X component software library is included with each motorized device such that its control features can be incorporated into any Visual Basic, C++, J++, or LabView application. The Active-X library is designed for use in Microsoft Windows 98/ME/2000/XP computers only. However, users can write their own software interface for other operating systems by referencing the RS-232 ASCII command interface manual provided.

 Application Software The 9490SD comes with Sci-Mono, which is an MS-Windows based ActiveX component software that can be used to control the monochromator/spectrograph independently, or imbedded into a larger software application. For Sci-Mono to work, it requires a custom configuration file that is specific to the gratings installed. Full featured Windows application such as Sci-Spec and Sci-LDA which operate the 9490SD with detectors and other motorized accessories are also available at additional cost.

Grating Choices A wide selection of 102 x 102 mm and 84 x 84 mm gratings are available. These include ruled gratings (300 l/mm, 600 l/mm, 1200 l/mm) and holographic gratings (1800 l/mm, 2400 l/mm). Selected gratings are also available gold or aluminum coated. Select gratings are available with kinematic mounts which allow for easy removal and replacement of the grating, without requiring realignment. This feature is useful if the application requires that the gratings be exchanged frequently. The gratings that do not have kinematic mounts are more difficult to remove, and require realignment, recommended for more static applications.