A document discusses a “solution-assisted contacting” technique for optical contacting. An optic of surface flatness Lambda/20 was successfully contacted with one of “moderate” surface quality, or Lambda/4. Optics used were both ultra-low expansion (ULE) glass (Lambda/4 and Lambda/20) and fused silica (Lambda/20).
A stainless steel template of the intended interferometer layout was designed and constructed with three contact points per optic. The contact points were all on a common side of the template. The entire contacting jig was tilted at about 30°. Thus, when the isopropanol was applied, each optic slid due to gravity, resting on the contact points.
All of the contacting was performed in a relatively dusty laboratory. A number of successful contacts were achieved where up to two or three visible pieces of dust could be seen. These were clearly visible due to refraction patterns between the optic and bench. On a number of optics, the final step of dropping isopropyl between the surfaces was repeated until a successful contact was achieved.
The new procedures realized in this work represent a simplification for optical contacting in the laboratory. They will both save time and money spent during the contacting process, and research and development phases. The techniques outlined are suitable for laboratory experiments, research, and initial development stages.
This work was done by Glenn De Vine, Brent Ware, Danielle M. Wuchenich, Robert E. Spero, William M. Klipstein, and Kirk McKenzie of Caltech for NASA’s Jet Propulsion Laboratory. NPO-47963
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Techniques for Solution- Assisted Optical Contacting
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Overview
The document discusses innovative techniques for solution-assisted optical contacting developed at NASA's Jet Propulsion Laboratory (JPL). Traditional optical contacting processes require high precision and cleanliness, often necessitating expensive components and clean-room environments. This research aims to simplify these requirements, making optical contacting more accessible and cost-effective.
Key findings include the successful contacting of optics with a surface flatness of Lambda/4, which is generally considered less than ideal compared to the recommended Lambda/10 or Lambda/20. The optics used in the study included ultra-low expansion (ULE) glass and fused silica, with some components having been left uncovered in a dusty laboratory for approximately five years. The cleaning process employed was less rigorous than typically required, yet it proved effective.
The cleaning and contacting procedure outlined in the document consists of several steps: scrubbing the optical bench and the optic surfaces with acetone and isopropyl alcohol, followed by applying a small drop of isopropyl for solution-assisted contact. Notably, the use of methanol, often recommended in other procedures, was found unnecessary. The researchers achieved successful contacts even in the presence of visible dust, demonstrating the robustness of the new techniques.
A stainless steel template was designed to facilitate the contacting process, featuring three contact points per optic and a tilted jig to utilize gravity in positioning the optics. This approach not only simplifies the contacting process but also reduces the time and costs associated with it, making it suitable for laboratory experiments and initial development stages.
While the document emphasizes the effectiveness of these techniques in a laboratory setting, it notes that further testing is needed to determine their suitability for flight applications, particularly regarding vibration and thermal tests. Overall, the research represents a significant advancement in optical contacting methods, potentially benefiting various technological, scientific, and commercial applications beyond aerospace.
In summary, the document presents a simplified and effective approach to optical contacting, highlighting the importance of cleaning procedures and the potential for successful contacts in less-than-ideal conditions, ultimately aiming to reduce costs and improve efficiency in optical component assembly.
