Frequently Asked Questions

Germanium is fairly non-reactive except with strong oxidizing agents. Both high temperatures and high vacuums can cause germanium to react with ethanol, but under normal conditions, ethanol and acetone are both safe to use on our germanium, including any of the lenses and windows that Edmund Optics® provides.

Lenses

Dust is the most common contaminant and can usually be removed using compressed air. If more cleaning is necessary, hold the lens in lens tissue and apply a few drops of reagent-grade isopropyl alcohol, reagent-grade acetone, or lens cleaning solution.

Mirrors

After blowing off dirt and dust with compressed air, the Drag Method of cleaning can be used to remove fingerprints or other contaminants. In the Drag Method, lens tissue saturated with reagent-grade isopropyl alcohol or reagent-grade acetone is slowly dragged across the surface. If done correctly, the solvent will evaporate uniformly without leaving streaks or spots.

Filters

Filters can be cleaned using the same methods as lenses or mirrors. The preferred method is to use compressed air or an air blower to remove dust.

Gratings and Wire-Grid Polarizers

Special care must be taken when cleaning gratings or wire-grid polarizers. Because the grooves are very tiny and delicate, the Drag Method is not recommended. The only recommended cleaning method is to use compressed air or an air blower to remove surface dust. Avoid methods that require any direct contacting of the grating surface. Ultrasonic cleaning should not be used as it may separate the grating surface from the glass substrate.

Holographic Diffusers

De-ionized water rinse, followed by a forced air drying. Wipe gently with lens tissue soaked with methanol, followed with a forced clean air or nitrogen drying. Note: Holographic diffusers are resistant to methanol and methylene chloride.

View Cleaning Optics for more in-depth information.

Most optics can be cleaned using the "drag method." If done properly, the solvent will evaporate uniformly without leaving streaks or spots. Exceptions to this method include gold-coated optics, gratings, ZnSe optics, and micro optics. For more detailed information on cleaning, view Cleaning Optics. We offer a vast array of cleaning products including tissues/wipes, solvents, compressed air, gloves, swabs, tweezers, etc.

Micro optics are extremely small and should be handled with extra care due to their small size. For example, micro lenses are typically classified as lenses smaller than 3mm in diameter. Delicate tweezers may be used to securely hold a micro optic by its edge, or a vacuum pick-up tool to secure it in place for cleaning. Compressed air or an air blower may be used to safely remove surface dirt; cotton-tipped swabs or lens tissue saturated with reagent-grade isopropyl alcohol, reagent-grade acetone, or de-ionized water is effective in removing smudges. Ultrasonic cleaning is not recommended as it may scratch the delicate micro optics.

View Cleaning Optics for more in-depth information.

Two methods are acceptable when cleaning holographic diffusers. One way is to use a de-ionized water rinse followed by forced air drying. The other way is to soak a lens tissue with methanol and wipe the diffuser clean (using the "drag method"), followed by either forced air or nitrogen drying.

See our Optics Cleaning Application Note for mirror cleaning techniques. Gold-coated mirrors are more delicate than aluminum-coated mirrors and can be easily scratched when using the drag method. Non-contact cleaning, such as ultrasonic cleaning, is the preferred method of cleaning.

Special care must be taken when handling and cleaning gratings. Handle only by the edges. Because the grooves are very tiny and delicate, the "drag method" for cleaning should not be used. Gratings have relatively soft coatings and are especially vulnerable to fingerprints and numerous aerosols, which can cause permanent damage.

For a detailed information on cleaning, view Cleaning Optics. Please note that some filters are coated and others are filters due to the glass itself (homogeneous) and therefore the two require different types of cleaning techniques.

The choice of adhesive depends upon your application. Adhesives can be classified into two groups: optically opaque adhesives and optically transparent adhesives.

Optically opaque adhesives are used when light is not going to be transmitted through the adhesive, such as when bonding a mirror to an aluminum mount. Milbond and Loctite® are two such adhesives. Milbond adhesive, for example, uses two bonding agents that, when combined, create the adhesive. There is also a decementing agent available for Milbond that allows the adhesive to be removed when necessary. These type of adhesives do not require UV light in order to cure.

Optically transparent adhesives allow light to transmit through and are commonly used to bond lenses together. The Norland and Summers lines are two such adhesives. When cured with a UV light source, the adhesive has a defined index of refraction which we list under the specifications of each adhesive. Please note that UV adhesives such as Summers and Norland do not come with decementing agents and are very difficult to break the adhesion once cured.

Yes. UV adhesives are optimized to cure under UV light. UV adhesives absorb UV light and pass the visible and IR portions of the spectrum. However, since sunlight and most room lights also emit in the UV, the adhesives will cure under these conditions. Please note that initial and full cure times will be considerably longer, because there will be less energy spread over a larger area then when compared to a UV curing light source.

The most common adhesive we use for bonding our prisms is Norland NOA61. It is low-shrink (so the pieces won't move as it cures) and has excellent bonding strength for glass-to-glass. The adhesive is UV cured, so you'll need a UV source to make it stick. Once cured the adhesive is opaque to UV light but still works great if you are going to use the glued prism pair for visible or NIR applications, in other words, you can expect high transmission from 400 - 2000nm.

Light Absorbing Black-Out Material is not tested for vacuum environments and the adhesive is likely to outgas in vacuum environments.