Optical manufacturing and testing spans an enormous range of manufacturing procedures and
optical test configurations.
The manufacture of a conventional spherical
lens typically begins with the generation of the optic's rough shape by
grinding a glass blank.
This can be done, for example, with ring tools. Next, the lens surface is
polished to its final form. Typically this is done by
lapping—rotating and rubbing the rough lens surface against a tool with the desired surface shape, with a mixture of abrasives and fluid in between.
Typically a carved pitch tool is used to polish the surface of a lens. The mixture of abrasive is called slurry and it is typically made from cerium or zirconium oxide in water with lubricants added to facilitate pitch tool movement without sticking to the lens. The particle size in the slurry is adjusted to get the desired shape and finish.
During polishing, the lens may be tested to confirm that the desired shape is being produced, and to ensure that the final shape has the correct form to within the allowed precision. The deviation of an optical surface from the correct shape is typically expressed in fractions of a
wavelength, for some convenient wavelength of light (perhaps the wavelength at which the lens is to be used, or a visible wavelength for which a source is available). Inexpensive lenses may have deviations of form as large as several wavelengths (λ, 2λ, etc.). More typical industrial lenses would have deviations no larger than a quarter wavelength (λ/4). Precision lenses for use in applications such as
lasers,
interferometer
Interferometry is a technique which uses the ''interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber op ...
s, and
holography have surfaces with a tenth of a wavelength (λ/10) tolerance or better. In addition to surface profile, a lens must meet requirements for surface quality (scratches, pits, specks, etc.) and accuracy of dimensions.
Fabrication techniques
*Glass blank manufacturing
**
Batch mixing Glass batch calculation or glass batching is used to determine the correct mix of raw materials (batch) for a glass melt.
Principle
The raw materials mixture for glass melting is termed "batch". The batch must be measured properly to achieve a giv ...
**
Casting techniques
**
Annealing schedules and equipment
** Physical characterization techniques
**
Index of refraction
In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium.
The refractive index determines how much the path of light is bent, or ...
measurements and calculation of melt pedigree
*
Diamond shaping
Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure, b ...
techniques
**
Diamond wheel
Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure, b ...
curve generation processes and equipment
**
Diamond edging
Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure, b ...
processes and equipment
*
Loose grit fabrication
Loose may refer to:
Places
*Loose, Germany
*Loose, Kent, a parish and village in southeast England
People
* Loose (surname)
Arts, entertainment, and media Music Albums
* ''Loose'' (B'z album), a 1995 album by B'z
* ''Loose'' (Crazy Horse album), ...
techniques:
** Rough grinding
** Fine grinding
**
Polishing
Polishing is the process of creating a smooth and shiny surface by rubbing it or by applying a chemical treatment, leaving a clean surface with a significant specular reflection (still limited by the index of refraction of the material accordin ...
and
figuring
Figuring is the process of final polishing of an optical surface to remove imperfections or modify the surface curvature to achieve the shape required for a given application.
Types
An example of figuring is that used in reflecting telescope ...
*
Single-point diamond turning processes and equipment
*
Glass moulding
Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenching) of ...
techniques
**
Precision glass moulding
Testing techniques
* Direct
surface profile measurement
* Direct surface surveying (no intervening optics, for example
Foucault knife-edge test,
Ronchi test,
Caustic test)
* Auxiliary optics (
null correctors,
computer-generated holograms, etc.)
*
Interferometric testing
See also
*
Optical lens design
*
Vapor polishing
Notes and references
*Malacara, D., ''Optical Shop Testing - 2nd Edition'', John Wiley and Sons, 1992,
External links
Virtual Lens Plant, Canon Camera MuseumInstructional videos of the processes, within a flash web interface.
{{DEFAULTSORT:Fabrication And Testing Of Optical Components
Optics
Optical components, fabrication
Glass engineering and science