Market Adjustors

There are a myriad of choices on the market when considering adjustors for micro range precision. Almost all fell well within the 5-micron adjustment limit. Unfortunately none met all of our needs.

Edmunds Optics (http://www.edmundoptics.com) lists a quality selection of manual micro positioning adjustors. The two most important criterions for our project are the adjustment to within 5-microns and athermability, which are both addressed within the specification table. The adjustors have a sensitivity of .5 microns, well within range, and a total travel of a quarter inch all the way up to half an inch. The problem is that, although the window for thermal stability is larger, from 15°C to 75°C, our design requires compliance from 10°C to 40°C.

Figure 4: Edmunds Adjusters

Specialty Motions (http://www.smi4motion.com) offers adjustors similar in style to Edmunds. These adjustors are also acceptable, being precise to within .635 microns. The adjustors are constructed of Aluminum carriage and base, hardened steel rods and rollers, mild steel end caps. As described above in the material properties descriptions, these materials have all shown an indication having a coefficient of thermal expansion too great for this application.

Figure 5: Specialty Incorporated Adjuster

Isotech Inc. (http://www.isotechinc.com) carries adjustors much like those from Edmunds and Specialty, but more importantly, they also carry a side drive version. The side drive version is of interest because the placement of the adjustors away from the pickup is desirable due to placement constraints. Again the adjustment is within range, at .635 microns. Again the adjustors are made of an aluminum carriage and base, hardened steel shafts and balls, and mild steel end caps, rendering them useless to us.

Figure 6: Isotech Adjuster

The parameters of our design presented a problem when choosing off the shelf adjustors to manipulate the receiver. Most readily available adjustors are constructed with an aluminum body and stainless steel rails. Since the design needs to be as athermal as possible, whichever material is considered needs to have a low coefficient of thermal expansion. As noted in the material section, aluminum and steel expand much more than what is desired within specification. This is the primary reason why we decided to construct a design where the adjusting controls could be disconnected after the unit was calibrated.