Composites Provide Thermal Protection for Optical Components
A glass-ceramic composite material addresses the technical requirements of digital rotary scanners.
Market research shows that the optical components market has grown 8-12% annually during the past five years.1 The optics market is intensely competitive, with demand increasing for optical components as communications markets, internet usage and the digitalization of information infrastructure grow. Within this market, the trend of miniaturization and high-speed performance applies increasing pressure on a product’s thermal and optical properties.
This situation influences all market segments. One product whose manufacturer found a quick solution to thermal conductivity is a digital rotary scanner. The optics industry equips digital rotary scanners with the capability to focus laser beams to take a reflective full-scale image of drawings such as those used in the architectural industry. In order to do so, a beam of light is projected over a rotary drum to copy the image. Yet the process is not as simple as it sounds; complex activities take place deep inside the spinning drum (or rotation axis).
Inside the drum or axis, a metal shaft with optics at one end is used to focus the light beams (see Figure 1). To prevent vibration that could disturb the scanning process, the metal shaft is cushioned by an air bearing. While the rotary drum spins, the air bearing runs at high speeds and can sometimes generate heat over the metal shaft. This heat can be eventually transferred to the optics at the top of the shaft, thus affecting focus precision.
Finding a Solution
In order to resolve this particular problem, MACOR® was inserted between the shaft and the optics to prevent thermal transfer. The mica glass-ceramic material is easily machinable using conventional metalworking tools (no post-firing is required). The ceramic material’s technical strength and insulation properties exceed high-performance plastics, and it is also stable in high temperatures (continuous at 800°C, up to a peak of 1,000°C) with zero porosity and outgassing. In addition to being tolerant (as little as 0.0005 in.), it can be machined to a surface finish of less than 20 micro-inches and polished to a smoothness of 0.5 micro-inches AA. The ceramic material also acts as an electrical insulator that is radiation resistant and has low thermal conductivity.
The low-density, machineable glass-ceramic material fit the requirements of this application. The manufacturer of the digital rotary scanners tested the glass-ceramic’s properties. During the production process of the rotary device with the previous solution, the company had invested in incredibly sensitive optics that could not operate without a heat barrier. In this case, the manufacturer had to wait for many months for another set of optics to be designed.
Within weeks of using the glass-ceramic, the manufacturer solved the problem with heat transfer and secured new sales of its rotary digital scanners. Another advantage over other ceramic materials is the fact that it was very easy to incorporate into the production process. The glass-ceramic material fulfilled the manufacturer’s needs of speed of response, machined to high accuracy and low thermal conductivity. The manufacturer’s problem could have taken months to resolve, but the glass-ceramic provided the solution in such a short space of time that it enabled production to continue with minimum downtime.
- “Optical Components Market Growth Picking Up Again in 2015,” IConnect007, http://ein.iconnect007.com/index.php/article/88922/optical-components-market-growth-picking-up-again-in-2015/88925/?skin=ein.