Glass Cover Slip for "high" pressure applications

Hi I'm developing a high pressure acrylic flow cell for microbiology studies. The flow cell has a hollow center that allows the placement of a 30 by 60mm glass cover slip. The cover slip is secured around its edges by clamping in between two pieces of arcylic. The design is such that direct observation can be made using a microscope. I'm now trying to source for a suitable glass material. My main question is, given a flow cell internal pressure of 2 to 4 atm, what type of glass is suitable and what is the thinnest glass i can use? Other properties such as anti-reflective, scratch resistant will be nice.

Thanks philip

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I presume that the need for a thin window is set by the microscope depth of focus?

Well, I'd be tempted to reduce the window area first - do you need to scan across a large lateral field with the microscope or will it be fixed and staring? If the latter, then you could have a jolly small window retained by a polycarbonate mask, machined to allow the microscope lens' structure to get nice and close to the window with a little jiggle-room built in.

We run windowed vacuum systems here, granted, only 1 bar differential, and have 4mm thick windows 60mm in diameter - but these are MgF for spectroscopy so a quartz or *a* glass would give much thinner windows for the same span. Ultimately, I'd go for the absolute smallest window that is useful, maybe even remake the flow-cell - it sounds a bit big... and then scale down from commercial windows.

A vacuum window manufacturer (Crystran are nice people) may help - but they're spectral specialists and I suspect that your doing visible microscopy... tricky. Otherwise Google says:

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-James Garry

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James Garry

Chromatic aberration?

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Gregory L. Hansen

The formula is helpful: t=D*sqrt(S*K*P/(4*Fa))


S=safety factor See text below Fa=Tensile strength Fa=48.92 MPa for fused silica K=constant K=1.125 for unclamped edges of the window P=pressure differential across the window t=thickness of window

However I can't find a reference to it. Anyone know where this comes from?

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