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Questar logo from 1990's (27,482 bytes)


Questar QM-1 Short Mount Long Distance Microscope (71,691 bytes) The Questar QM-1 Long Distance Microscope is the innovative instrument for which the Questar Corporation received an "Industrial Research Magazine" award as one of the 100 most significant new technical products of the year in 1983. This was the first of a series of compact and lightweight long-distance microscopes developed by us which for the first time allowed images to be made of microscopic subjects in enclosures, in hostile environments, in process and on-line. Microscopic resolution could be achieved from a longer distance without cluttering the work area with instrumentation.

Right: Current production QM-1 Long Distance Microscope, Long Mount variant with lens cover aside (71,691 bytes).
Click on image to see enlarged view (164,054 bytes).

The QM-1 Long Distance Microscope are lightweight and offer superb performance and at reasonable cost for general industrial or research applications or for teaching. With a working range of 56cm (22 inches) to 152cm (66 inches), a 30 to 1 variability in field of view, and remarkable depth of field, linearity and chromatic correction it is an indispensable tool for a wide variety of laboratory and industrial applications. The QM-1 includes two selectable ports so it is compatible with both Questar Brandon 1.25" Eyepieces or many third party standard slip-fit eyepieces, and with with 35mm SLR and with common digital and video camera formats.

These are compact round barrel instruments provided with a precision machined aluminum mounting ring, this ring is provided with a selection of tapped and threaded holes so that the instrument may be supported on steady fixtures or built into another device, or the instrument may be installed onto any of Questar's line of fixturing and transit/measurement positioning stages.

The original version of the Questar QM-1 Long Distance Microscope was an arrangement that resembled the Field Model, a conventional telescope, but the QM-1 differs in that it has a longer barrel length. Over time improvements were made to improve boresighting accuracy and this has resulted in the current QM-1 Long Distance Microscope optical tube assembly. This Short Mount configuration is available as is shown at right, in its standard configuration. The short mount instruments are the lightest of the group and feature a rotatable control box which allows viewing or diverting the light cone, or attaching a co-axial light source from either side of the microscope. This may be used effectively even when attached onto a suitable photographic field tripod.

Questar QM-1 Long Mount Long Distance Microscope (114,018 bytes) For applications that require the most rigid bore sighting accuracy for measuring, precision alignment with heavy payloads etc., then we offer the QM-1 Long Mount arrangement. The long mount instruments has the same optics set and Control Box arrangement of the Short Mount, but the tube features a mounting pad which extends the length of the barrel. Otherwise, the Short Mount and Long Mount instruments will offer identical optical performance.

Right: Current production QM-1 Long Distance Microscope, Long Mount variant with lens cover aside (114,018 bytes).
Click on image to see enlarged view (256,982 bytes).

The standard BK7/MgFl2 Optics Group provides transmission spanning 350 to 2000 nm. While the optional Fused Silica/MgFl2 Optics Group provides Transmission Range spanning 180 to 4000 nm. There have been several generations of the QM-1 since these were first introduced (with the purple anodized barrel) and each of the newer models has brought noteworthy improvements in performance and durability. The improvements in coatings durability has been particularly important as many of these instruments are employed with lasers and other high power sources.

Specifications (mechanics based on standard QM-1):

Optical Characteristics:

  • Design: Maksutov-Cassegrain Catadioptric
  • Standard Corrector Lens: BK7, MgF2 AR Coated; multilayer dielectric coatings optional
  • Optional Corrector Lens: Fused Silica (for enhanced UV spectral response), MgF2 AR Coated
  • Primary Mirror: Pyrex substrate, aluminum coated with SiO overcoat; Zerodur substrate optional
  • Primary Mirror Diameter: 96mm (3.78 inches)
  • Corrector Lens Clear Aperture: 89mm (3.5 inches)
  • Standard Secondary Mirror: aluminum coated with SiO overcoat; silver with ThF4 overcoat optional
  • Secondary Mirror Diameter: 22mm (0.87 inches)
  • Baffling: Helix in central tube, all interior surfaces black anti-reflection coated

Mechanical Characteristics:

  • Barrel Material: Aluminum hollow bar, machined from seamless stock.
  • Barrel Length: 24.8cm (10 inches)
  • Control Box: Cast aluminum, 24S-T4, corrosion resistant; selectable axial or 90 degree Port.
  • Internal Barlow Lens: 1.5x selectable for 90 degree port, flick knob controlled
  • Internal Prism: standard, flick knob controlled
  • Tube Assembly Length: 33.8cm (13.32 inches) front cell to focus knob fully extended
  • Tube Assembly Diameter: 10.7cm (4.23 inches) maximum overall
  • Tube Assembly Height: 20.3cm (8.0 inches) base of mount to top of eyepiece
  • Tube Assembly Weight: 1.47 kg (3.25 pounds)
  • Mount: Full length rail of machined aluminum, 1/4"-20 and 3/8"-16 mounting holes
  • Barrel can rotate (260 degree range of motion) in its mounting collar
  • Focus Mechanism: Mirror thimble integral with stainless steel (s.s.) sliding tube.
    Slides on fixed stainless steel light baffle tub (centerless ground). Conical s.s. spring loaded.
    Focus rod 303, precision ground, 24 TPI; integrated inside control box
  • Finish: Aluminum components anodized natural, dark blue, or black
  • Carrying Case: ATA, Furnished Standard


  • Focus Range: 56cm (22 inches) to 152cm (66 inches)
  • Optical Resolution: 2.7 microns at 55.9cm (22 inches)
  • Format: Diffraction Limited Field 12mm diameter, 18mm nearly D.L.
  • Distortion: 1 part in 15,000 edge to edge
  • Back Focus Distance: 70mm (2.75 inches) minimum measured from back plate
  • Field of View (2/3" format): 0.9mm (0.035 inches) to 15mm (0.59 inches)
  • Standard spectral response: 330nm to 2.3 microns, optional systems with wider spectral response available.
  • Optional extended Ultraviolet or Infrared imaging response: from below 200 nm to 3.5 microns
  • Optional EXFO X-Cite illumination sources and accessories, including the high stability X-Cite exacte system.
Questar QM-1 Long Distance
Microscope Drawing
Above: QM-1 Short Mount Long Distance Microscope Dimensions (108,952 bytes)

Object Distance Numerical Aperture f/No.
1400mm (55 inches) 0.0288 16.8
1020m (40 inches) 0.385 12.9
700mm (27.5 inches) 0.0511 10
560mm (22 inches) 0.0580 8.7


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