SPI Supplies Quartz Microscope Slide, 1 x 3 in. (25 x 76 mm) x 1 mm Thick,each
SPI Supplies® Quartz Microscope Slide, 1 x 3 in. (25 x 76 mm) x 1 mm Thick,each
There are many microscopy laboratory operations and procedures where UV transparency is an absolute requirement. There is of course the obvious case where one might be doing UV microscopy, but there are also other applications where one is irradiating a sample with UV irradiation and quartz must be used for the container of the liquid being irradiated. The window of highest transparency to UV is between 0.15 µm to 5 µm. Transmittance information for the quartz used for the standard SPI Supplies Brand of quartz products, GE 124, as well as that for other types of GE quartz is available.
Generally speaking, quartz slides and cover slips are recommended for most applications involving chemical microscopy, in order to be sure that nothing is "lost" due to absorption in a glass slide. The use of quartz slides and cover slips are also recommended whenever UV microscopy is contemplated, including UV confocal microscopy because of the high UV transparency of quartz.
SPI presents a very high quality, state of the art, family of clear fused quartz based products. These items are manufactured from the very highest purity clear fused quartz. Our vendor-partner making these items in cooperation with SPI is a leader in the quartz field and uses proprietary processes that give these quartz products an "edge" over all others.
Putting it another way, the SPI quartz products are made to the same standards that are used for quartz products in the electronics industry, recognized as being the very highest standards in the world. Some might say this extra quality for more ordinary UV microscopy applications might be overkill, and perhaps it is, but we don't believe that this higher quality is necessarily reflected in costs that are going to be noticeably higher. In any case, veteran researchers often times comment about the extraordinarily high quality of the SPI Supplies® Brand of clear fused quartz slides and cover slips and express their belief that these are the very best quality available anywhere.
Actually we go beyond what most others can do:
Our superior technology permits us to offer quartz cover slips in Thickness #0 (0.075 - 0.125 mm thick). We are unaware of anyone else routinely making such thin cover slips to these specifications of thinness and flatness.
Impact of trace level impurities:
Even extremely low levels of trace impurities can cause some diminution of the transmittance of the quartz. When the very very ultimate is needed, SPI Supplies can now offer quartz slides in fused silica, a form of quartz that is even higher in purity than GE 124. For this highest level of quality in quartz, we fabricate in Corning® 7980 fused silica.
Description of the quartz used in these products:
The starting material for all SPI Supplies quartz slides and cover slips is always GE 124 fused quartz. This is the "standard" for the electronics industry and is the top of the line so far as quartz products are concerned.
This question often times arises and the SPI quartz slides and cover slips are made to a typical flatness of 2-4 "bands" per in., but quartz in 1 mm thickness can bend under its own weight. When placing an optical flat on top to measure flatness, the slide or coverslip will conform to the flat, but when on top of an optical flat, it does not weigh enough to flatten itself out. We are told that slides and cover slips can not be made with greater flatness than just indicated.
Not to be confused with the term "flatness", the roughness, which is sometimes referred to as "smoothness", can be measured with AFM and while we can't guarantee it as a specification, our periodic measurements with AFM suggest that the typical roughness is better than 2 nm. Some of our customers are now asking us to supply them with quartz slides that exhibit a surface roughness better than that. We are now able to offer the SPI SuperSmooth™ quartz slides and cover slips with surface roughness better than 0.5 nm (again, as measured by AFM).
All quartz is not the same! The quartz offered by SPI Supplies is considered to be the premier quality of quartz and the full transmittance data is provided to our customers. And index of refraction data can be equally important for others. We demand that General Electric Brand of quartz starting material be used exclusively for the production of the SPI Supplies offered quartz products.
High temperature applications:
The SPI Quartz Slides are often times used as substrates for high temperature experiments and we are asked about how high in temperature the slides can be taken before changes occur. That temperature is about 1250°C (2282°F) as the slide will start to soften at about this point. We do not have information about how materials being annealed might react with quartz at elevated temperatures so such experiments should be done cautiously, at least the first time. For those customers interested, the coefficient of thermal expansion of the GE 124 quartz (20° C to 320° C) is 5.5 X 10-7 cm/cm x °C.
Standard thickness specifications:
The standard tolerances for the SPI quartz slides are as follows:
- Standard thickness tolerance: ± 0.005" (127 µm)
- Variation over a batch of slides: Could be as much as 0.005" (127 µm)
- Variation along a single slide: Could be as much as 0.002" (51 µm)
One does not normally see specifications published for quartz slides. We are obviously confident that these tolerances are far tighter than is normally found. And for an extra charge, we can provide still tighter tolerances on the thickness of the slides. Obviously, variation in thickness can have a deleterious effect on some kinds of data.
But we do apologize for the relatively high cost of these small items made from quartz, especially when compared to the price of comparable items in glass. However, the process to make them is an expensive one and there seems to be no alternative routes to lower priced products that possess the same high quality. However, despite the high quality of the SPI quartz products, if you price compare, you will find that our prices are still lower than most of the alternatives. At the present time, Thickness #0 (0.075 - 0.125 mm thick) mm in thickness is the very thinnest that these cover slips can be produced. Note that this minimum thickness starts to increase as the lateral dimensions of the cover slip increases because the yield (breakage rate) increases exponentially as the area goes up. We might be able to produce thinner cover slips, but the lateral dimensions would be very small.