ASI offers the following zoom optical systems from Qioptiq (formerly Thales Optem). These systems have the diversity and modularity to cover fields of view of several microns to a few meters. Follow these links to Qioptiq web pages for more information.
An optical zooming system is a lens system that can change magnification. Qioptiq zooming video microscopes are all finite conjugate zoom systems. This means that they have an object plane and an image plane in fixed locations during the zoom. These zoom systems change the magnification, and therefore the field of view, as they are zoomed.
Why A Zoom System?
There are two primary reasons for choosing a zoom system over a single focal length lens.
- Inspection
A zoom provides the ability to rapidly scan a large area and then magnify a point of interest to see fine detail, without changing optics or refocusing.
- OEM Automation
Many automated manufacturing and inspection systems are required to process a wide variety of object sizes. For the computer to achieve maximum accuracy, it is desirable to use as much of the imaging sensor as possible, therefore as the object size is increased or decreased, the magnification can be decreased or increased respectively. In fact, all Qioptiq zoom systems are now available with computer control capabilities that permit rapid changeover of job setups using preprogrammed codes and standard line operators.
Selecting A Zoom System
An overwhelming majority of zooms are used with video cameras therefore it is assumed that the camera format (2/3”, 1/2”, 1/3”, etc.) is known. (E.P. holders are available for visual work).
Three other factors are significant:
- Working distance (WD)
The mechanical clearance between the end of the lens and the workpiece.
- Maximum size of an object to be viewed
Field coverage or Field of View (FOV).
- Minimum size detail to be viewed
Resolution. Think of resolution as a function of the numerical aperture (N.A.) of the system. The larger the N.A., the better the resolution.
| Bare Zoom Characteristic (WD Approx. 90mm [75mm for T100]) |
| Zoom |
Zoom Range |
High Mag |
Low Mag |
High N.A. |
Low N.A. |
| 70XL |
7X |
5.2X |
0.75X |
0.08 |
0.024 |
| T100 |
10X |
7.5X |
0.75X |
0.19 |
0.019 |
| 125C |
12.5X |
6.5X |
0.52X |
0.10 |
0.019 |
| 160 |
16X |
8X |
0.50X |
0.15 |
0.009 |
The table above shows the optical characteristics of the bare zoom modules. You will note that the actual magnifications, along with the accompanying Numerical Apertures, are given for the extremes of zoom travel.
The chart above shows the comparative field coverage and resolution for three different zooms at equivalent working distances. The resolution is given as “threshold resolution” which is adequate for a computer to determine an edge with the appropriate algorithm but, for visual work, the numbers should be reduced by a factor of 2.
The center section of the chart (90mm W.D.) reflects the values shown in the bare zoom characteristics table. The sections on each side show what happens when auxiliary optics are added on the bottom to modify the working distance. Observe the direct relationship of N.A. to resolution and the inverse of field coverage to magnification.
All of the zooms have comparable accessories for modification of magnification and working distances. Also, motorization and illumination capabilities are similar. As the magnification range and resolving power increase, the size, weight, complexity, and cost follow. Refer to the sections on the individual zooms for more detail.
