Sciencetech FWG-8 motorized filter wheel has eight filter positions. Each filter position accepts 1” diameter round filters up to 5mm thick. The filter wheel is a compact pancake design with an exposed stepper motor mounted on one side. This stepper motor can be computer controlled via an optional MD-100 stepper motor controller module, which connects the motorized filter wheel to the RS-232 serial port of a PC computer. The MD-100 is an external unit that provides power and communications to the motorized filter wheel for filter position selection. The MD-100 also interfaces with a PC host computer via RS-232 serial commands. A Windows based Active-X component Sci-FilterWheel library allows programmers to incorporate high level filter wheel logic controls into their own software application. This active-X software is available free of charge. Sciencetech’s Sci-Spec and Sci-LDA monochromator and detector software applications (which are sold separately), can also control the motorized filter-wheel via the optional MD-100 controller. Please note that individual filters are also sold separately.

Purchasing Filter-Wheel without MD-100 Controller
The FWG-8 motorized filter-wheel is designed to be controlled with Sciencetech's MD-100 Stepper motor controller. If a customer wishes to purchase the FWG-8 Filter-wheel without the MD-100 stepper motor controller, the customer must provide their own stepper motor controller to control it.

Bi-Directional Rotation
When used with Sciencetech MD-100 Stepper Motor Controller and Sciencetech Sci-FilterWheel Active-X software, the filter-wheel can change slot positions bi-directionally. For example, if the filter-wheel is on Slot Position 3, the Sci-Filterwheel software would instruct the filter-wheel to move forward to Slot Position 4 or move backwards to Slot Position 2. It would not say, move from Slot Position 3 to Slot Position 2 by going forward around the entire slot positions. However, there is still one small software flaw that needs to get fixed. Since Sci-Filterwheel software is used universally for all Sciencetech filter-wheels from the 4 slot model to the 8 slot model, it cannot apply this intelligent logic at the cross over point from the last slot to the first slot. For example, in a 4 slot filter-wheel, it would still go back 3 positions from Slot Position 4 to Slot Position 1 rather than going forward one position.

Light Tight Housing and Flat Surface Mounting
The aluminum housing is light tight and with the stepper motor mounted on one side of the filter-wheel, the opposite side remains completely flat without obstruction for mounting purposes.

Homing Switch
The Filter-wheel has a built-in IR optical switch for home position detection. Please note that there is only one home position on the entire wheel that corresponds to the first slot. It does not have multiple home positions corresponding to each filter slot position. Please note that the Sciencetech MD-100 Stepper Motor Controller and Sci-FilterWheel Active X software supports reading this home position switch. A third party stepper motor driver may not.

Direct Drive Shaft Coupling System
The filter-wheel is coupled directly to the stepper motor's drive shaft without any gearwork or belt drive. This reduces backlash and assures the rotation precision is as precise as the micro-stepping capability of the stepper motor which is 2000 counts per 360 degree revolution. Since the stepper motor is always energized even in a stopped position, there is no noticble backlash or positional drift once stationary in a slot position.

Supports 1" or 25mm diameter filters
The 1" diameter slots of the filter-wheel can also hold 25mm diameter filters since 25mm is slightly smaller than 1" (25.4mm). The filters are held in place by a top retaining ring which presses down onto the edge of the filter and works whether they are 1" diameter or 25mm diameter. Due to the retaining ring, the clear aperture is reduced to 23mm diameter.

Technical Specifications
Filter Sizes: 1” or 25mm diameter, up to 5mm thick (sold separately)
Motor: 12V, 90W per winding, 200 steps per revolution stepper, Mfg - Koll Morgen SM39Y2-U61 or equivalent
Electronics Controller: Sciencetech MD-100 Stepper motor controller module microprocessor based,
two 8-bit stepper motor controller ICs(7 plus sign:-127 to 127)
Communication: RS232 handling standard ASCII commands, serial cable
Min.Adjacent filter switch time: 400 ms
Clear Aperture: 23mm
Diameter: 139.7 mm (5.5")
Thickness 25.4 mm (1")
Center of Beam Light: 76.2mm (3") Software: Windows based Active-X component (ASCII commands)