Large Spatial Filter

This system is constructed especially for applications which require easy and open access to all the individual parts; a version optimized for applications in which space is limited is described here.

The construction of this spatial filter ensures that the two key adjustment processes (focusing along the optical axis and aligning the pinhole in two directions perpendicular to it) are completely independent of one another and makes it possible to interchange the expansion objective (micro objective) in a simple way.

This spatial filter is an assembly of three modules: an objective focusing unit MRF 56.1 (the middle part in the above photograph, with a 14 mm diameter mounting post); an adjustable pinhole attachment MRF 56.2 (on the right in the photograph) which is mounted on the top of the focusing unit; and an objective holder, which is part of MRF 56.1 (on the left in the photograph, shown with an objective). The two adjustable parts are connected together by a groove and four clamping screws. The parts can also be ordered individually.

The short focal length objective for focusing into the pinhole is screwed into the objective holder (left item on above photo) by means of a standard RMS microscope thread and then inserted into the focusing unit so that the focal point is approximately at the pinhole plane. A knurled ring on the focusing unit makes it possible to fine focus without rotation of the optics. The objectives must have at least 0,2 mm free working distance.

In the adjustable pinhole unit the mounted pinholes are held by a side clamping screw and are easily interchangeable. For adjustment of the spatial filter the pinholes can be smoothly moved in X or Y direction by two micrometer screws. A side viewing opening in the adjustable unit facilitates the adjustment.

Ordering Information

• Large Spatial Filter Complete:
  Objective focusing unit with objective holder and adjustable pinhole unit on 14 mm diameter mounting post, but not including objective component or pinhole. → MRF 56
• A microscope objective and a pinhole are required in addition.

Parts

• 1. Objective focusing unit, single:
  with objective holder and mounting post, micro objective not included → MRF 56.1
• 2. Adjustable pinhole unit, single:
  pinhole not included → MRF 56.2
• The MRF 56 spatial filter is a combination of both separate units MRF 56.1 and MRF 56.2.

Accessories

• Short focal length microscope objectives for use in the spatial filter are described here .
• All the optics listed on that page are cement-free which means that they can also be used with high-power lasers. For the expansion of low-power laser beams, all conventional microscope objectives can also be used with the spatial filter as long as they have a standard RMS objective thread (Witworth 0.8" * 1/36") and maintain 45 mm parfocality (based on DIN 58887). Because the lens holder is adjustable, objectives with other parfocal distances (ca. ±12 mm) can often be used too.
• Pinholes for use in this spatial filter are described here.
• Long focal length objectives for the collimation of filtered and expanded laser beams.
• Some types of long focal length objectives are in stock, please contact us with your requirements.