Optical Cementing Station VP 30532

The quest for better and better imaging quality of optical systems (such as lenses) yields tighter and tighter tolerances for the design and assembly of the individual optical elements. Hence, increasingly high demands are made on cemented elements, i.e. two or more lens elements glued together by suitable UV curing cements. The optical axes of the single lens elements forming these cemented elements have to be aligned first before joining them by means of short flashes of UV light. That alignment shall not be affected by any curing distortion of course.

Our Optical Cementing Station VP 30532 uses the measuring head and reflected image method established already in our Centering Tester VP 30508, allowing measurement of the centring error with unsurpassed accuracy of up to 0.01 arc minute. As the measuring method does not require any head lens and both, setting up the v-edge to diameter of the lens under test and focusing the measuring head on to the lens surface is motorized – with database connectivity if desired – set-up times are negligible when cementing different lens types one after another.

Prior to loading the base and top lens into the cementing station, the two lenses usually will be prepared for the cementing process. Therefore a suitable amount of the optical cement will be applied on the base lens. Afterwards the top lens will be placed on top of the base lens. By carefully moving around and by applying gentle pressure the optical cement will be dispensed homogenously and free of bubbles. Now the two lenses are loaded on to the lens support ring of the optical cementing station. By means of a friction wheel drive (or the optional motorizied rotary stage) the base lens is set in rotation. Due to the viscosity of the optical cement the top lens is rotating with the same speed too. While measuring the centring error the operator will then optimize the alignment of the top lens element by carefully jolting its lens edge. At last, both lens elements will be joined together by means of short-time illumination with UV light. The UV light source is not included in the scope of supply, however, the measuring head features a receptacle for a light guide as commonly used with UV light sources.

Handling of small and lightweight lens elements can be accomplished with the optional motorized air bearing rotary stage VP 30508-600. It can be inserted in the worktop instead of the replaceable lens support rings while the friction wheel lens drive is in park position. No matter whether the lens support rings or the motorized rotary stage is in use, the lens element under test can be prevented from unintended lift-off by applying negative pressure if required. For small and lightweight lens elements it is also advisable to use an optional pneumatic pusher enabling non-contact alignment of the upper lens element.

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