Browse Prior Art Database

Alignment System

IP.com Disclosure Number: IPCOM000087508D
Original Publication Date: 1977-Feb-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Hooker, WL: AUTHOR

Abstract

In this system, a ring 1 (Fig. 1) of light scans the circular aperture 2 of opaque member 3. Juxtaposed on the opposite side of member 3 is a CdS photocell 4 having an optical axis 5 coincident with the center axis of aperture 2, (Fig. 2). Cell 4 is connected to a suitable display, e.g., photometer 6. The inside diameter of ring 1 is slightly larger than the diameter of aperture 2.

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Alignment System

In this system, a ring 1 (Fig. 1) of light scans the circular aperture 2 of opaque member 3. Juxtaposed on the opposite side of member 3 is a CdS photocell 4 having an optical axis 5 coincident with the center axis of aperture 2, (Fig. 2). Cell 4 is connected to a suitable display, e.g., photometer 6. The inside diameter of ring 1 is slightly larger than the diameter of aperture 2.

It is assumed that the central axis 7 of ring 1 is initially offset in the X-Y direction, as shown in phantom outline in Fig. 1. Waveform A (Fig. 2) indicates the light intensity profile of the cross-section of ring 1 for this position, and waveform B indicates the resultant output of cell 4. Due to the characteristics of CdS cell 4, the indicator 8 of meter 6 is at a high position, as shown by its phantom outline in Fig. 2.

As ring 1 moves in the X direction indicated by arrow 9, (Fig. 1), a decreasing amount of light of ring 1 is detected by cell 4. As result, when the axis 7 of ring 1 is in alignment with the Y-Y axes of aperture 2 (Fig. 1), cell 4 detects a minimum of light due to the corresponding shift in the light intensity profile A' of ring 1. Thus, there is a decrease in the output B' of cell 4 and the indicator 8 is at some minimum position, as shown by its solid outline form in Fig. 2. Further movement of ring 1 in the direction 9 or in the reverse direction would cause indicator 8 to move towards the high end of the meter scale.

Once alignment in the X-X d...