Resolv4K® Modular Zoom Lens Components

Features

• Build High-Magnification Zoom Lens Systems for Machine Vision and Other Imaging Applications
• 7X Afocal Manual Zoom Lens with 0.4X to 2.8X Magnification Range
• Working Distances from 32.3 mm - 173 mm
• Ideal for 2/3", 1", 4/3", or 32 mm (APS) Senor Format Cameras
• Compatible with Objectives or Lens Attachments (Sold Below)
• Zoom Lens System Optimized for 445 nm - 655 nm Range
• 0.61 - 55 mm Field of View (See the Field of View Tab for Details)
• Use 7X Zoom Lens and Rear Adapter to Build a Zoomable Tube Lens

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Figure 1.1  An example configuration of a Resolv4K zoom lens system.

The Resolv4K^®1 Modular Zoom Lens Components allow users to build high-magnification zoom lens systems that are ideal for machine vision and other imaging applications. The core 7X afocal zoom lens must be used with a rear adapter (sold below) and can be used with either a magnifying lens attachment (sold below) or microscope objective. Resolv4K zoom lens configurations can support a wide field of view ranging from 0.61 mm - 55 mm and working distances from 32.3 mm - 173 mm (see the Field of View tab for details). Thorlabs also offers 6X and 12X high-magnification zoom lenses that have built in objective lenses and are designed for machine vision applications that require long working distances.

The modularity of the Resolv4K zoom lens components allows users to design their own configurations to meet a range of imaging needs. The MVR4K is an afocal zoom lens that is infinity-corrected on both the object and image side, and is optically designed to be apochromatic from 430 nm - 670 nm. In addition to machine vision applications, these components can also be used as a zoomable infinity-corrected tube lens for widefield imaging. Users can easily build a zoom microscope using a rear adapter, the core afocal zoom lens, and an infinity-corrected objective, as shown in Figure 1.2. This system is designed to provide near diffraction-limited images over a large field of view with minimal vignetting.

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Figure 1.2  The Resolv4K system can be used as a zoomable infinity-corrected tube lens. By using any infinity-corrected objective, the appropriate coupler, zoom lens, and rear adapter, users can construct a zoom microscope. 

A complete modular zoom lens system consists of the MVR4K 0.4X - 2.8X afocal zoom lens (7X zoom range), a rear adapter (0.6875X, 1X, 1.375X, or 2X), and an optional magnifying lens attachment that includes fine focus adjustment (0.5X, 1X, or 2X), as well as a camera mounting adapter and a coupler to hold the lens attachment (all sold separately below). Together, these components can be configured to achieve focal lengths ranging from 64 mm - 448 and provide a net magnification of 4.5X - 18X with a 7X magnification adjustment range. The magnification adjuster (zoom) is a recessed rotating collar on the barrel of the core afocal zoom lens. We also offer a variety of adapters that allow users to modify their system. To connect a camera, we have two mounting adapters with either a Nikon male F-mount or external C-mount (1.000"-32) threading for compatibility with our C-Mount sCMOS or CMOS cameras. Alternatively, the lens attachment can be replaced by a user-selected objective. To connect an objective instead of a lens attachment, we offer couplers for M25 x 0.75-, RMS-, or M26 x 0.706-threaded objectives. For additional information on building a zoom lens system, please see the Assembly and Adjustments tab.

Magnification Calculation
The net magnification, M, of the system (M = image size / object size) is equal to

,

where f_{Rear Adapter} is the rear adapter focal length, f_Objective is the objective focal length, and M_{Zoom Lens} is the zoom lens magnification, which ranges from 0.4X - 2.8X. When using a lens attachment in the system, the objective focal length is the lens attachment focal length.

If a system is made up of all Resolv4K components, another equation for calculating the net magnification is

,

where M_{Rear Adapter} is the rear adapter magnification, M_{Lens Attachment} is the lens attachment magnification, and M_{Net System} is the magnification of the entire Resolv4K zoom lens configuration, which ranges from 0.64X - 4.5X. For example, the zoom lens system can be set to a magnification between 0.64X and 4.5X (corresponding to a 7X zoom range). If it is used at its maximum magnification setting of 4.5X, along with a 2X rear adapter and a 2X lens attachment, the maximum system magnification of 4.5 x 2 x 2 = 18 is realized. See the Specs tab for the maximum and minimum magnifications of each lens combination.

1. Resolv4K is a registered trademark of Navitar Optical Solutions.

• For more specifications on the lens attachments and rear adapters, please see Tables 2.2 and 2.3.
• Minimum resolvable feature size is half of the threshold line pair limit [Minimum Feature Size = 1/(3 x NA) µm]
• The low and high system magnification values are calculated using the lowest (0.64X) and highest settings (4.5X) on the MVR4K zoom lens. Please refer to the Magnification Calculation section on the Overview tab for more details.
• The 0.64X - 4.5X magnification is assuming a 1X lens attachment and 1X rear adapter. This is the magnification range of an entire Resolv4K system; used on its own the MVR4K zoom lens has a magnification range of 0.4X - 2.8X.

• The fields of view are measured diagonally across a 4:3 aspect ratio sensor. (Horizontal = Diagonal x 0.8 and Vertical = Diagonal x 0.6) 
• The high and low magnification values are calculated using the zoom lens magnification settings (0.64X - 4.5X).
• The 0.64X - 4.5X magnification is assuming a 1X lens attachment and 1X rear adapter. This is the magnification range of an entire Resolv4K system; used on its own the MVR4K zoom lens has a magnification range of 0.4X - 2.8X.

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Figure 4.1  An exploded example configuration of a Resolv4K zoom lens system to help assist when assembling and disassembling components. Note the location of the setscrews for each dovetail connection.

Assembly

With the exception of the mounting adapters which use threads, all Resolv4K^® zoom lens components are connected together via dovetails that each can be secured using the three included M4 setscrews. To avoid damaging the components, we recommend tightening the setscrews using a 2 mm hex key to a torque of 20 in-oz (0.14 N·m). When assembling and disassembling the zoom lens system, be sure to adjust the appropriate setscrews for the dovetail connections; see Figure 4.1. We recommend assembling the components in the following order:

1. Thread the rear adapter's external M42 x 0.75 threads into the mounting adapter's internal M42 x 0.75 threads.
2. Secure the rear adapter's female dovetail onto the zoom lens' male dovetail using the three included M4 setscrews; see the example configuration (Figure 4.1) for the locations of the setscrew holes.
3. Secure the zoom lens' female dovetail onto the coupler's male dovetail using the three included M4 setscrews; see the example configuration (Figure 4.1) for the locations of the setscrew holes.
4. If using an objective, thread it onto the coupler. If using a magnifying lens attachment, connect the coupler's female dovetail to the lens attachment's male dovetail. Secure with the three included M4 setscrews.
5. Attach the camera to the mounting adapter. If a C-mount camera is used, attach it via the external C-Mount (1.000"-32) threads on the mounting adapter. If an F-mount camera is used, attached it via the male F-mount on the mounting adapter.

For disassembling, we recommend doing the assembly steps in reverse.

Parfocality and Boresight Adjustments

On the rear adapter, users can set the parfocality of the zoom lens system. This allows users to adjust the magnification without losing focus. To set the parfocality:

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Figure 4.2  Rear adapters offer boresight and parfocality adjustability. 

1. Set the magnification to the highest setting and adjust the z-axis until the best focus is achieved.
2. Set the magnification to the lowest setting. Do not adjust the z-axis to refocus.
3. To refocus, rotate the parfocality adjustment collar on the rear adapter.
4. Once in focus, secure the parfocality adjustment collar by tightening the two M3 setscrews using a 1.5 mm hex key; see Figure 4.2.
5. Zoom to high magnification. Do not adjust the z-axis to refocus.
6. Repeat steps 3 and 4.

Boresight can also be adjusted on all rear adapters. This allows users to change the magnification without the image shifting positions. To do this, adjust the M3 setscrews on the top of the adapter using a 1.5 mm hex wrench; see Figure 4.2. The boresight adjusment can be simplified by aligning one of the screws along either the x- or y-axis of the sensor, then adjusting screws on opposite sides of the adapter, along that axis, to “push” the image in that direction.