Germanium Lenses

Our Germanium lenses are perfect for Mid-Infrared applications. These lenses stand up well to harsh environments and we offer the most popular sizes with Anti-Reflection Coatings. Germanium is subject to thermal runaway, meaning that the transmission decreases as temperature increases. As such, these lenses should be used at temperatures below 100°C. Germanium’s high density (5.33 g/cm3) should be considered when designing for weight-sensitive systems. The Knoop Hardness of Germanium is 780, making it ideal for IR applications requiring rugged optics.


  • High Index of Refraction
  • Minimal Chromatic Aberration Due to Low Dispersion
  • Perfect for Rugged IR Applications
  • Popular Sizes Available with AR Coating from 3-12μm

Factory Standard– Contact us for manufacturing limit or custom specifications

  • Substrate Material: Ge (Germanium)
  • Diameter:  5mm-350mm
  • Shape: Spherical Plano-Concave, P-Convex, Concave-Convex or Aspheric
  • Focal length: +/-1%
  • Surface Quality: 20-10(after coating)
  • Surface figure: l/4 @ 633nm
  • Clear Aperture: >85% of central dimension
  • Antireflection Coating: @ 3-12 um

Further study of CdWO4 crystal scintillators as detectors for high sensitivity double beta experiments

Energy resolution, light yield, non-proportionality in the scintillation response, alpha/beta ratio, pulse shape for gamma rays and alpha particles were studied with CdWO4 crystal scintillators.

Some indication for a difference in the emission spectra for gamma rays and alpha particles was observed. No dependence of CdWO4 crystal pulse shape on emission spectrum wavelengths under laser, alpha particles and gamma ray excitation was observed.

Dependence of scintillation pulse shape for gamma quanta and alpha particles and pulse-shape discrimination ability on temperature was measured in the range of 0-24 degrees.

This article comes from arxiv edit released

Crystal growth of strontium titanate SrTiO3

SrTiO3 crystals have been prepared by flame-fusion growth and from KF-LiF and K-Li-borate fluxes.

The crystals are characterized by EPR, absorption spectra, chemical analyses and 7-rocking curves, and the structural perfection of flame-fusion and flux-grown crystals is compared.

This article comes from tandfonline edit released

UV Range Stepped Neutral Density on fused silica for full uv range control

We custom and standard neutral density optical filters for a wide spectrum of applications. These include machine vision, HPLC, gas chromatography, instrument calibration and flourescence microscopy.

Our online catalog continues to grow. The listed bandpass, longpass, shortpass, and neutral density optical filters are just a few in our expanding inventory. Please call or email us if you don’t see the filter you need. Our goal is to provide you with a perfect filter solution for your product or research project.

Our flexibility to run small prototype lots and custom setups at low cost have helped companies develop their products using our neutral density optical filters.

This article comes from maierphotonics edit released

Crystal optics

Compared to the previous options, this product has many benefits that far outweigh its failings. In our opinion, this is the best solution to go for when choosing IR Windows optics.

There are many different types of crystal IR Window materials. The most common being germanium. This material is found on your infrared camera lens and can either be purple or orange in colour, depending on the coating that has been used.

Germanium is known in the industry as the ‘grey transmitter’, which means that its transmission loss is consistent across the whole of the infrared spectrum. This factor makes it fantastic for lenses as it modulates the IR signal the same way regardless of wavelength. Also, the addition of anti-reflective coatings (AR) makes windows manufactured from this material extremely good infrared transmitters. Unfortunately, germanium can be expensive, and using this material to manufacture a 4″ IR Window would mean they would would end up retailing over $2000 per unit, which rules it out.

Another material which can be used is sapphire, which is very durable and would be able to withstand a hammer impact. But, similar to germanium, this is still a very costly material.

This leaves two materials, which are both ‘flourides’ – Calcium Flouride (CAF2) and Barium Flouride (BAF2). Both of which have been used as optics in the past, but although BAF2 is highly transmissive and great for measurement, it can also be susceptible to moisture and somewhat toxic.

CAF2 is the least expensive option here and is the optimum IR Window optic material. Although it can be brittle, properly coated CAF2 optics do not degrade over time and any errors in reading caused by the optic can be corrected reliably and repeatedly with a properly configured infrared camera. Taking all of this into consideration, we prefer HydroGARD coated CAF2 over the other options as the positives far outweigh the negatives.

Carbon Flouride is homogenous, meaning that its transmission characteristics are consistent across the face of the IR Window. This means that a properly configured IR camera can correct any errors and provide the thermographer with a truly representative temperature measurement. This material is also optically and thermally transparent and is not only transmissive to IR and visual cameras, but to UV cameras as well.

This article comes from cord-ex edit released

Cleaning Germanium Lenses: Choosing the Best Method

Cleaning germanium lenses elements improves performance, providing proper materials, techniques and handling procedures are used to minimize the risk of damage.


Optics can be contaminated in many ways. Contamination can be kept to a minimum by returning the optics to their case after use or by covering the optics for protection from the outside environment. However, even with all these precautions, the optic will eventually accumulate dust, stains or some other form of contamination.

Inspection of germanium lenses surfaces

During inspection, all optics must be handled in the cleanest area available (preferably a cleanroom or within a laminar flow bench). Proper equipment, such as powder-free cleanroom gloves or finger cots must be worn at all times to avoid grease and oils from being transferred to the optic. Lens tissue paper, dust-free blowers, hemostats, cotton swabs, cotton tips, and reagent-grade acetone and methanol, will all be needed for cleaning optics. The acetone and methanol must be fairly fresh to avoid leaving any marks on the optics. Reagent-grade isopropyl alcohol can also be used instead of acetone.

Pro Tip: Clean optics against a dark background so dust can be seen and eliminated more efficiently.

There are two ways in which an optic can be evaluated:

• If the optic is being used in a laser-based system, contamination on the optic might cause the optic to scatter the laser light, thus reducing power and making the optic “glow.”

• An optic can also be visually inspected by holding it below a bright light source and carefully viewing it at different angles. This will cause the light to scatter off the contamination enabling the viewer to see the various stains and dust particles.

Cleaning methods

1) Blowing method
2) Drop and drag method
3) Wipe method
4) Bath method
5) Soap solution method
6) Ultrasonic cleaning method


Historically, germanium lenses components such as mirrors and beamsplitters have been cleaned by hand, using lint-free germanium lenses wipes and reagent-grade acetone or another liquid solvent such as methanol, ethanol, 97 percent pure isopropyl alcohol, methyl ethyl ketone (MEK) or methylene chloride (MEC). Some inorganic acids such as trichloroethylene (TCE), hydrofluoric acid (HF) and hydrochloric acid (HCl) may be used on uncoated silicon wafers, and nitric acid may be used on germanium substrates. Acidic solutions, however, should never be used on coated or uncoated zinc sulphide (ZnS) or zinc selenide (ZnSe) components.

Acetone is very good at dissolving grease, but it dries very quickly and always should be handled with acetone-impenetrable gloves. In general, isopropyl alcohol is a safe and effective cleaner – except for cleaning aluminium coatings. Because alcohol reacts with aluminium, it should never be used on protected or bare aluminium-coated mirrors. Methanol and most acidic solutions can be toxic or damaging to optics or coatings if misused, so care should be taken to follow the instructions provided by the manufacturer.

Liquid CO2 is a new technique that is used to remove oils and microscopic particles from germanium lenses waveguides, electro-germanium lenses devices, silicon wafers and a variety of biomedical, aerospace and semiconductor components. This process delivers a precisely controlled and purified spray alternated with warm air cycles to the germanium lenses surface. Because CO2 is noncorrosive and relatively nontoxic, it is safer to use than many traditional solvents, but it requires nontraditional procedures and a controlled, moisture-free work environment and so may incur additional expenses. In the long term, however, it may turn out to be a less expensive and a more effective means of achieving ultraclean surfaces, possibly resulting in coatings with higher damage thresholds.

Storage conditions

Once you have cleaned the optic, place it in the mount it will be used in or wrap it in lens tissue and place it in its container right away. The proper container to use is a polycarbonate/PTFE/PET-G box, in a cleanroom environment. The room temperature should be kept between 15 and 25 °C (60 to 80 °F). Ideally, humidity should be controlled and kept below 30 percent.

CAUTION: Do not use a polypropylene box. Studies have shown that permanent outgassing of the storage box leads to adsorption of products detrimental to laser resistance of coated optics.

This article comes from photonics edit released

IR Windows Optics: What’s Available?

One of the first things we need to get our heads around when it comes to IR cameras, is what they can do and what they can’t. This will ultimately lead us to what an IR Windows Optics are and the crucial factors you must take into consideration when thinking about investing in them. One of which, considered the most important factor, is the “optic” material that they are manufactured from.

What is an IR camera?

An infrared, or IR camera is a very clever piece of technology in that it can actually see heat.

Some of you may recollect a very famous movie in which soldiers are seeking an extraterrestrial being using an infrared camera. Although there have been significant advances in the technology of IR, the functionality is demonstrated very well here.

The way that IR cameras work is that they use a completely different part of the electromagnetic (EM) spectrum to the part that the human eye uses. This is known as the infrared part of the electromagnetic spectrum.

The advances in microbolometer technology – which is essentially a sensor within a camera – makes the IR camera an exclusively ‘uncooled’ system. This is a relatively new form of sensor which comes with lots of advantages, including the fact that it removes the need of a cooler due to it’s runtime extension. These types of cameras tend to operate in what is known as the ‘longwave’ or 8-14μm section of the electromagnetic spectrum.

What materials can be used for an IR Windows optics?

IR Windows Optics– which are used to perform fast and safe infrared surveys of electrical equipment across all industry sectors – require certain materials that are transparent to infrared in the band that the particular camera you are using operates in. At the moment there are three different options of optic material that are typically available.

This article comes from cord-ex edit released