Many modern scientific instruments require glass bulb formation as a critical step during their manufacture. The craft of glass blowing dates back to the 1st Century BC, and it became widespread during the growth of the Roman Empire. This discovery enabled a revolution in glass production, shrinking production times from about one hour to a few minutes for most core-formed objects (such as bottles and flasks). This reduction in processing time made glass objects affordable for most citizens. It also spawned a glass luxury market where single items could take hundreds of hours to craft. Demonstrations of glass blowing are still a popular staple at renaissance fairs, artisan communities, and museums.

Despite its association with antiquity, glass blowing is still required to properly form glass for many different high technology applications. Ironically, some of the most sophisticated high accuracy scientific devices utilize manual glass blowing processes to properly shape the required glass components.

Xenon arc lamps

One example is the Xenon arc lamp, commonly used in many analytical devices. Xenon arc lamps come in a variety of formats, primarily differentiated by associated electronics and glass bulb shapes. The emission spectrum of Xenon is ideal for many applications which require large photon flux in the UV range (250-400 nanometers). Despite the availability of higher power UV LEDs, much higher photon flux can be achieved by utilizing a Xenon arc lamp.

Figure 1. Comparison of emission spectrum of a Xenon arc lamp to incandescent lamps; note the UV region between 300-400nm where Xenon excels.

Another application is the use of Xenon lamps for UV curing of the epoxys. This technique is used in the construction of many high tech devices – ranging from smart phones to telescopes. High performance lenses, fiber optic cables, fiber optic arrays, and other demanding manufacturing processes utilize epoxies cured by Xenon lamps. This reduces optical strain caused by mechanically mounting optical devices. The power and consistency of UV range light output is critical for this process. Proper shaping of the glass bulbs used in these systems is still carried out using techniques very similar to traditional glass blowing.

Sensor production

Another common application for glass blowing is in the production of sensors, including pH sensors. These sensors require glass encapsulation and a small bulb to contain the final electrical sensor assembly. The bulbs are generally created by glassblowers who are able to process these small, delicate systems. These glassblowers are experts with amazing manual dexterity and many years of experience and professional development. Several electrodes must then be inserted into a perfectly formed glass bulb to create the common electrical pH probe.

This process can be automated using an Alicat mass flow controller in conjunction with off-the-shelf robotics. Typical outputs for glassblowing of a small volume can be as little as 10 CCM of air expelled over a period of a few seconds. These controllers can be ranged with full-scale flow rates as low as 0.5 SCCM, with a controllable range of 0.01 to 100% of full scale and accuracy as good as ±0.5% of reading. Utilizing a mass flow controller to automate glassblowing can add greater accuracy and reliability to this ancient process, while providing the additional benefit of automation.

Courtesy of Alicat Scientific

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