Shuttering system for a sensitometer

Abstract

A shuttering system for a sensitometer is taught which can be used both conventional and high speed exposures. The shuttering system includes a high speed rotating sector shutter, a rotating capping sector shutter, a mask and a sample transport all of which are precisely controlled relative to one another. Located closest to the sample of radiation sensitive material is the mask having three different width slits therein. The different width slits produce different and predictable exposure times when the sample is moved past at a constant velocity. Positioned behind the mask is the high speed sector shutter which is a thin disk having two different size exposing apertures therein located 180.degree. apart to thereby produce different exposure times depending on the rotational speed of the disk. The rotating capping shutter is positioned behind the high speed shutter and has one aperture therein. The first way uses the sample transport system to move the sample past one of the slits in the mask at a constant velocity. For short exposure times of 4 msec to 100 .mu.sec, the high speed sector shutter and the capping sector shutter are spinning synchronized to each other and synchronized to the position of the sample transport. The rotation of the capping shutter is synchronized with the high speed shutter so that the exposing apertures of each shutter are aligned during an exposure. The spinning of these two shutters is also synchronized with the sample transport so that light passes onto the sample precisely when each test object step is centered on the exposure plane.