We are attempting to view the tubes in a hydrogen furnace running at ~800C through a viewing port with Vycor glass and not having any success. We have an AGEMA 550 (3.6 to 5 micron range) imager as well as a FLIR P65. Ant ideas on materail of construction for the viewing port windows? sapphire, quartz etc.

Thanks,

These are probibly saphire glass viewing ports.

Firstly, does your Agema 550 have a flame filter fitted?
Secondly, are you able to see anything through the port with either camera?

Vycor can be found on http://www.pgo-online.com/intl/katalog/vycor.html
it seems to 90% silica. I would expect the P65 to be no use for this application anyway as you should have difficulties with seeing through the flame and there should be poor transmission through silica in the LWIR region.

Silica should have a cut off around 3.9 microns, and this is the region where the flame filter operates. You might have some success in this region using a flame filter. If you have problems you could try using a lower temperature range and a neutral density filter, just forget about temperature measurement though.

The ports currently have Vycor which we believe to have a range that is around 2.5 microns. Our AGEMA does not have a filter. Our next step is to probably replace the Vycor with sapphire lens.

If you cannot see anything through it, then you will have to replace it. Saphire glass is a good choice as it will work well with the Agema 550. You need to forget about the P65 for this application anyway as the 550 is more suitable.

Do you have an extended temperature range on your camera? or does it cut off around 500 Degrees C?

The AGEMA has a range that goes to 1500C. Their appears to be a built in filter for through the flame viewing. I have not used the imager a great deal its used mainly as a back up.

The high temperature range on the 550 is done by adding a 3.9 micron flame filter. You are looking at a very narrow part of the spectrum. You will have to use a different material than the Vycor, saphire glass would be the best material.