Dream was created to make advanced composite technology more accessible to opto-mechanical customers. Advanced composites, when designed properly and for a specific need, can far surpass the strength, stiffness and lightweight characteristics of today's metals. Their CTE's can be substantially lower (and in specific cases negative CTE's are possible) than common metals. Click here to see a comparison showing why advanced composites are so beneficial compared to metals.

 Dream's specializes in the use of advanced composites, mostly carbon fiber, in combination with sandwich core technology. To learn more about the enormous benefits of sandwich core, click here

 Dream was also created to push past boundaries both in telescope & accessory designs. An attempt is made at every turn to use composites instead of metals, both for thermal stability and light-weighting. The latter can have thermal benefits for the instrument, as well as stiffness benefits. Thermal characteristics can far outway other criteria in a telescope system. But stiffness will always be one of the core requirements of any opto-mechanical system. Optimizing the performance of both the thermal aspects and the stiffness of the system can allow the utmost in performance and the highest throughput.

 Many companies use carbon fiber products that have a clear, glossy finish. This leaves the part with one of two commonly used weave patterns, 2x2 twill or plainweave. Unfortunately this also leaves the part charcoal black. This color exterior will heat up the interior of the OTA and therefore the optics, when exposed to the Sun. It will take that much longer for the optics to cool down. Dream has tested black surfaced materials in moderate temperatures, 70°F, and found that they easily reach 160°+ degrees in the Sun! This is a potential problem for all composite parts, not just opto-mechanical products. Please read below for an explanation.

Using bright white (some silver paints work too) greatly reduces the amount of heat buildup and therefore promotes the quickest equilibrium times. Excess heat in advanced composites can also facilatate a breakdown of the laminate, especially with room temperature cured resins. Layers of reinforcement (fiberglass, carbon fiber, etc.) will start to delaminate from each other, for example, if a temperature threshold is exceeded. This can be prevented by using high temperature epoxy that allows cooking the advanced composite parts. This raises their properties so that they do not have delamination issues, if designed and produced correctly. Dream has always used a specific high temperature, high performance epoxy (~$110/gallon) that can be cured at up to 350F, if the application requires it. This also allows us to produce mirror mounts, backplates, telescope structures, etc., that are close to 1ppm/°C of the mirrors that we use.

In sandwich core use temperatures are again a factor that must be considered. Some foams and honeycombs ($100-$300 per 4'x8' sheet) can only withstand temperatures of 230°-250°F. If the product will see temperatures above this, specialized cores like Nomex honeycombs or Rohacell foams can be used ($250-$700+ per 4'x8' sheet). 

To learn more about the background of Dream and elevated temperature epoxy, click here.

 Epoxy resins are UV sensitive, as are most resin systems. They will degrade if directly exposed to UV rays. Composites should always be protected with a UV barrier layer(s) to help increase the longevity of the product.

To learn more about advanced composites, click here.  

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