QUESTAR SZ90 Motorized Step Zoom Lens

Illustrated above: Questar Step Zoom 90 System with Keypad Control Terminal

The Questar Step Zoom 90 Multi Focal Length Optical System is a very compact and lightweight, fully motorized, parfocusing (as magnification is changed the instrument can automatically refocus to compensate), rugged, microprocessor controlled Maksutov Cassegrain Catadioptric Optical system with a clear aperture of 89 mm and a base focal length of 1280 mm at F/13.5, with a focal length range in steps of between 480mm to 3100mm. While the MFL systems are have manually operated control functions, the SZ functions can all be controlled remotely from a simple to learn and use keypad/terminal. The lens is weatherized with seals and "O" rings throughout, and with protective optical flat windows at the front and rear.

The SZ 90 system internal optical components and baffling system have been designed to maximize light transmission and minimize all optical aberrations to increase overall system performance to unprecedented 1/6 wave PV minimum; and so it is able to display on a TV montor a 7mm (1/4 inch) feature at 1 kilometer. Each instrument is tested to assure at least Arc Second resolution. The enhanced mechanics provide for a rapid focal length and focus transition when in the Parfocal mode, with switching generally not to exceed 1 second.

Available Effective Focal Lengths:

Focal Length	Focal Ratio	T Stop
480mm	f5.4	T6.6
660mm	7.4	T9.1
820mm	f9.2	T11.3
955mm	f10.7	T13.1
1280mm	f14.6	T17.8
2230mm	f25.0	T30.6
3100mm	f34.8	T42.6

Each unit will come with hardware that will allow it to be controlled locally from a furnished microprocessor keypad controller, or from a lap top computer's Com Port, or by modem for longer distances telecommunication. The system software has the ability to control or monitor features such as Focus, Focal Length, Filter Position, Automatic light control (ALC), and more.

The SZ 90 system comes equipped to accept any standard video camera with "C mount" lens thread. The system is equipped with four selectable focal lengths, and up to five selectable filters. This permits the system to operate at relatively low magnifications providing a wide field of view, or zoom in to reveal very fine details in a distant target. The system is typically employed with video cameras with 2/3 inch diagonal CCD formats, larger detectors would provide wider fields of view. An example of the range of field of view is illustrated in the following table:

above: Possible Fields of View of Questar Step Zoom 90 System with optional 2/3" video camera
(Field of View is from 0 to 100 Meters, Distance Scale is from 1 to 5 kilometers)

SZ 90 Optical Specifications:

• Design Type: Maksutov Cassegrain
• Clear Aperture: 89 mm (3.5 inches)
• Effective Focal Lengths: 480mm, 660mm, 820 mm, 955, 1280 mm, 2230 mm, 3100mm 6:46: 1 zoom ratio
• Corrector: BK-7, magnesium fluoride AR coated
• Primary Mirror: 96mm Pyrex aluminum coated, SiO over coated
• Secondary Mirror: 28.7mm aluminum coated, on R2 of Corrector Lens
• Working Focus Range: 15 meters to infinity
• Resolution: 1.0 arc second
• Format: Diffraction limited 18 mm @ 1280 mm EFL
• Auxiliary Lens: Achromatic, magnesium fluoride AR coated
• Filters: Schott colored glass, 400 nm, 450 nm, 650 nm, 750 nm long pass filters
• Light Control Filter Bk7 optical glass. Neutral density 0 - 2.5. Inconnel coated
• Baffling: Helix, knife-edge stop rings and anti reflective painted

Terminal Keypad Control Description and Functions:

• Thirty key hand control unit, with four line twenty character backlit supertwist display
• Keypad audible beep, switchable on/off
• Communications RS-422 standard, 9600 baud
• Distance from terminal to instrument can be up to 4000 feet (1220 meters)
• Selection of Focal Length by direct access buttons or seqeuntial up/down
• Selection of Filter by direct access.
• Bidirectional turret drives rotate in direction of shortest travel to next selected position
• Parfocalization software to maintain focus for all focal length changes, selectable on/off
• Adjustable focus acceleration and velocity
• Last possition and motion paraameters svable as power up defaults

• Barrel Section: Machined from solid aluminum stock, black anodized.
• Front Lens and Rear Cell Protective Optically Flat Window, AR Coated
• Focus: Transiting corrector design. Mirror housed in Aluminum cell. Supported on six precision linear bearings on non-stressed rods, precision lead screw drive. Variable speed DC servo motor with encoder for position feedback to terminal.
• Turret Section: Lens and filters 110 min (4.5 inch) Dia. direct tooth belt drive. Machined and anodized. Bronze bushings and roller thrust bearings on 3/4" inch Dia. stainless steel shaft. Up to five colored 25.4mm or 38 mm diameter filters and up to five lenses in a spring-loaded adjustable bore sighting cell. Stepper motor and direct tooth belt drive. Electronic plunger solenoid lens wheel position lock for boresight accuracy.
• All functions driven by 1.8 degree step motor open loop drive with microprocessor control. Opto interrupter for end of travel and home position sensing.
• Cover: Aluminum black anodized form 1/16th inch thick cover skin
• Finish/Hardware: All exterior surfaces black anodized. All hardware stainless steel. Exterior is also Prolane painted Black. Custom colors can be specified.
• Mounting: 1/4" - 20 TPI, or 3/8" - 16 TPI mounting holes on bottom of plate. Custom pattern and sizes to suit your need
• Dimension: 12 inches long (ALC adds 0.75 inch), 8.7 inches tall, 8.3 inches wide
• Weight: Instrument 10 pounds, Terminal 1 pound, Power Supply 1.1 pound
• Power Requirement: 12VDC @ 1.5 amp
• Power Supply Provided: Auto Switching 90-250 VAC/47-63 Hz. IEC Power input for worldwide use.

Options Include:

• Automatic Light Control (ALC): with manual override. Electronic module will automatically react to changing lighting conditions. The gain setting in auto mode is controlled from user interface.
• Linear Wedge Filter: Manual neutral density variable light control. Two Inconnel. coated linear filters mounted on two pillow block linear slides and motor controlled from user interface. Bk7 optical glass. 0.625" Thick. Neutral density range 0 - 5.0.
• Environmental heater/cooler
• Pan/Tilt and Elevation Mount Head, and Pier or Tripod
• Video Transmission site to site
• High Transmission Coatings
• FS Corrector for extended UV sensitivity
• Special Purpose Filters
• Environmental Enclosure: Environmentally sealed aluminum fabricated lightweight enclosure. This unit includes a 10 inch Dia. coated optical protective flat, .5 PSI two way pressure relief valve, "O" ring and gasket seals, electronic solenoid valve and pressure sensor combination to control internal pressure, brass pressure fitting, sealed BNC connectors and sealed round Bendex connector for power and communication feed. All exterior surfaces are black anodized and Polane painted. Industrial textured black paint is standard. All hardware stainless steel. Custom colors can be specified.
• Peltier heater/cooler: Thermoelectric device (Nema 4X rating) integrated into the enclosure to provide temperature regulation while maintaining the sealed integrity of the enclosure. The unit has several modes of operation. An internal auto protection preset to 35 degrees C and user interface setting control. The system software will monitor the user set values against the internal temperature and automatically control unit. Requires 24VDC to operate.
• Variable Polarizer: Motorized polarizer assembly that can be moved in and out of optical path. When in the optical path Rotation Control will allow the user to change polarizer position to attenuate glare and light