Lens manufacturing in steps
Calculation of individual lenses
Freeform is a new way of corrective lens manufacturing. It is based on nanoHDVision technology for calculation of optical surfaces at all individual lenses – Magic Alpha, Sport, Acomoda and unifocal. It allows for the highest optical quality at every point of the lens surface and in all viewing directions.
The technology takes into account all the individual characteristics of the user – physical as well as biometric. It is recommended that the optician enters into the order form any other specific information about the customer; for example, we can make lenses with widest possible far vision zone for the drivers (model Outdoor), for working indoors we can make lenses with widest possible near vision zone (model Indoor).
We offer the optimal design selection to people in virtually any profession.
Variable inset (nasal shift of near vision zone in relation to far vision zones) significantly expands near vision zones by considering different convergences. For the users with larger pupil distance and larger convergence, lenses with larger inset are made, and vice versa. It is also possible to make lenses with variable inset, also asymmetric if pupil distance to the left and right eye is different. If the leading eye (if the other eye has a low visus) does not converge, it is recommendable to make a lens for the leading eye without the inset – near vision zone will thus be utilised in full.
When making calculations, we also consider pupil height, pantoscopic tilt of PANTO glasses, horizontal wrap of the ZTILT glasses, distance of cornea from the lens – vertex or BVD.
Dimensions and shape of the eyepiece (in combination with previously mentioned individual data) enable the concentration of simulation rays in the eyepiece, so the calculation of surfaces is extremelly efficient and precise.
|information on pupil distances IPD, fitting height (OCHT), and sizes of eyepiece and bridge||pantoscopic tilt PANTO and vertex distance from cornea to the lens (BVD)|
|horizontal wrap of frame ZTILT and
front curve of lens F BASE
| horizontal and vertical decentration
HDEC, VDEC – based on input data are calculated automatically
Calculation of individual lenses – continued
|software for calculating individual lenses|
Using this information we calculate lens surface (infinite number of points), with nanometric accuracy. The result are lenses with larger vision zones and smaller peripheral aberrations. The user gets used to the lenses very quickly. Even at longer and demanding tasks the eyes remain rested. Lenses manufactured with this technology are top-quality personalised product.
Using this advanced technology we avoided cases of customers not getting used to MAGic progressive lenses, especially Alpha in Alpha VIP, which can be mounted also in wrap-around sport glasses.
Similar is true of Sport lenses which enable comfortable viewing with sport glasses and wrap-around sunglasses to the users with higher diopters.
Because rays fall onto the lens under a certain angle, we encounter aberrations in the form of unwanted cylinders and prisms. The power of these errors depends on several parameters, especially on horizontal index ZTILT and vertical tilt PANTO.
In all individual lenses these errors are addressed with compensation, so that the user is given the required diopter at each point on the lens surface.
Measuring these lenses with an ordinary focimeter will give different data from the data on the ordered lenses, which is why one must refer to the data that include compensation when checking these lenses.
Lens thickness optimization – CTO
In Alcom we can, using the eyepiece silhouette and positions of pupil centers, computationally determine optimal lens thickness – Computer Thickness Optimization – CTO.
– thickness matching,
– lens optimization for nylor,
– lens optimization for screws.
|Printout of thickness calculation – more about that …|
Freeform manufacturing of individual lenses
|Satiloh Orbit VFT|
Manufacturing of individual lenses is done on Satisloh automatic devices.
Linear motors with tools made of natural diamond, cinematic control with nanometric accuracy, and self-calibration lead to precision in surface design.
|fine surface processing with natural diamond|
|automatic measuring of the surface|
Polishing with flexible tools
robot for manipulation with flexible polishing tools
computer-controlled polishing process
Individual lens control
Manufacturing of lenses requires advanced software and computers, experienced operators, precise machines for surface processing, and quality diamond and polishing tools. Only if each of several tens of parameters is correct, we get a quality lens that enables perfect vision.
For the analysis of freeform individual lenses we use automatized computer-guided instrument Dual LensMapper by Automation&Robotics. This is a state-of-the-art tool that checks in detail all points of a freeform lens. Every optical lens manufactured at the company is tested.
Such exact and quick checking of lenses eliminates any potential problems – human factor, materials, machine error, damaged tools, …
Automatic engraving detection examines the location of progressive surfaces. Diopter is measured with two types of rays – reflection checks individual surfaces, while transmission uses several thousand rays to measure optical performance of the entire lens. The comparison of measured values with theoretical ones is offered in 2D and 3D report for manual evaluation of results, whereas the computer, using ISO tolerance values, confirms whether the lens is flawless.
Each measurement is recorded in the database for subsequent analysis.
automatic device for measuring optical analysis of surfaces using reflection and
the surface of a freeform lens multi-point analysis with transmission
automatic engraving detection ensures the correct
position of optical surfaces
UV-A and UV-B PROTECTION and POLARIZATION
Longer exposure to UV radiation increases the risk of permanent eye damage (early cataract …). Certain damage can be treated, while other can lead to permanent loss of vision. UV radiation is completely invisible and consequently more dangerous, especially on sunny days when UV index is very high. Also dangerous is altitude UV radiation (in the mountains and where there is snow, the reflection off the snow is dangerous), as the radiation increases by 10% every 1000 altitude meters.
Therefore, quality sun lenses are very important. We recommend darkening over 75%, i.e. both-sided UV protection coating, or at least inner anti-reflection coating.
All additional protective coatings are permanent.
Natural light creates discomforting glare when it is reflected off the following surfaces: ice, snow, asphalt, water, windscreen. Polarization filters can prevent this glare.
Lenses are available in the following colours: gray, brown, green, and the new colour, 60% gray which can also be darkened. The lenses can be made with indexes 15, 16 and 167 and in variations Sport, Magic and as ordinary unifocal lenses.
Unbreakable polarized lenses are also available in NXT material.
The advantages of polarized lenses are:
– glare prevention,
– UVA and UVB protection,
– better contrast,
– extremelly sharp vision,
– detection of natural colours.
|Most popular sun colour.
Perfect for strong sun and light.
Ensures correct colour detection and low colour distortion.
|Improves colour contrast, stressing red and green colours.
Blocks blue light.
Reduces eye fatigue.
|Improves contrast in poor light conditions.
Reduces eye fatigue under strong light.
|Similar characteristics as Gray 3, but lets more light through.
Available in any colour with over 65% darkening.
|Ensures correct colour detection and low colour distortion.||Improves colour contrast and reduces eye fatigue.||Improves contrast in poor light conditions.
Reduces eye fatigue under strong light.
|Improves colour contrast through green and red maximums.
Darkens from 55 to 80%
Colouring and hard coating – HC
Users are becoming more and more aware of how important is to protect the eyes against strong sunlight, which is why many users choose sunglasses with coloured corrective sun lenses.
What are the advantages for the user?
– quality colours and efficient and permanent UV protection,
– quality is checked with spectral analysis using an industrial photospectrometer,
– colouring and coating do not affect corrective characteristics of the lenses,
– we offer warranty on our products.
– if using colour patterns, the lens colour is identical to original sun lenses,
– for drivers a transition darkness (viewing through a bottom, clearer part enables safe driving in a tunnel),
– an option of using two colours – bicolour,
– we consider user preferences, e.g. the length of transition,
– unlimited number of colours and shades,
– we also colour thinned lenses, e.g. 167 over 85%,
– lenses can be coloured with medical filters.
If adding hard coating or anti-reflection coating, please allow for minimal differences between the final colour and the sample.
Hard coating TS-HC
Hard coating is an extremelly important part of an organic lens. For hard coating we use automatic machines by Optimal Technologies.
In dustless chamber we use ultrasound cleaners to remove impurities, and also to activate lens surface.
In the second part of the process hard coating is added; everything is controlled by the computer. Because the surface is active, a permanent and strong bond between hard coating and lens is formed.
Finally, the layers are heat-polymerized to give them resistance to mechanical damage. Also, this makes hard coating ready for later addition of anti-reflection coating.
A combination of surface activation before adding hard coating and its hardness provide a very good resistance against mechanical damage and temperature changes. This ensures long service life and a good basis for Opal Ultra/UV anti-reflection coating.
Opal Ultra IAD – Ion Assisted Deposition
Opal Ultra is a package of lens enrichment, made on Europea machines and materials, and using European-based processes.
The basis for quality and permanent anti-reflection coating is quality hard coating.
Opal Ultra is made on computer-run machines by Leybold Optics. In a high vacuum (10-6 mbar) and using ions thin anti-reflection coating is added to reduce glare.
Then hydrophobic self-cleaning coating SuperClean is added to ensure smooth surface, which prevents greasiness and makes cleaning easier. These coatings reduce any contact between the lens and dirt and liquids to a minimum. Water drops practically bounce off the surface, contact angle is more than 115 degrees.
This coating makes lenses:
– extremelly smooth, which makes it more difficult for dirt and dust to get stuck to lens surface,
– easier to clean,
– less prone to fogging.
Lenses are smooth on touch, water drops “bounce off” the surface and flow off the lens.
Lenses with IAD coating have longer service life since it is more difficult for hard particles to reach the lens, and they cause less damage.
NEW: Corrective lenses with this coating have a two-year warranty. A temporary coating is added to prevent the turning of the lens during edging.
Quality of coatings is subjected to constant control and testing:
– computer control of steaming parameters,
– Bayer test of surface hardness,
– Weathering test of durability,
– Hot water test.
This gives us lenses with maximum light permeability ->99%, which enables cristal clear vision and makes lenses resistant to mechanical damage.
IAD – Ion Assisted Deposition
To increase the hardness of steamed coatings we use an ion canon that emits argon ions. It accelerates ions towards the lens, activating the surface and enabling layers to merge with hard coating. Bombarding with argon ions takes place during steaming of metal oxides, which increases their density.
Layers steamed in this way are:
– much stronger and resistant to mechanical damage,
– more resistant to temperature changes.
Regular anti-reflection coating – Opal Ultra with IAD (Ion Assisted Deposition)
porous layers, less resistant layers are compact and resistant to mechanical damage
Coating quality control
Quality and durability or coatings are important for user satisfaction. In Alcom, using different devices, we daily test samples of lenses made of different materials and having different coatings.
1. QUV or Weathering test is a reproduction of damage caused by weather conditions in several years of wearing glasses every day. Automatic tester device exposes lenses to strong UV light for several hours, followed by several hours of exposure to 100% humidity and 60° temperature. The process is repeated for 10 days and equals lens damage that occurs over 2-3 years.
2. Bayer test shows the level of lens resistance to mechanical damage. Front surface of a test lens and a control lens CR39 without coatings is inserted into a chamber containing abrasive sand. During testing the chamber with lenses is moved to and fro, and abrasive sand is moving across lens surface. A test sample with coatings is significantly less damaged than the control lens without any protection; the difference is even bigger when testing the lens with Opal Ultra coating.
3. For hot water test lenses are submerged into hot water with added salt, and then cooled in cold water. By repeating this test several times, we test the lens resistance to temperature shocks..
The last step involves mounting the lenses into the frame.
In Alcom, mounting is conducted on a 4-axis CNC machine, which is the only machine that can mount lenses into nearly any frame, even wrap-around sport frames.
An additional axis on the machine enables the manufacture of different bevels, dioptrical lenses are mounted in a sport frame, similar to normal lenses, without the process resulting in frame deformations or causing the lenses to fall out.