Optical Services: Optical Polishing & Lapping

Optical Services

Optical Glass Polishing Lapping Banner

Optical lapping and polishing are finishing techniques offered by manufacturers of precision optical components such as windows, lenses, glasses and other products to meet certain optical surface requirements.

The desired finish is achieved using a specially shaped tool that is rotated and rubbed against the lapped surface of an optical component with a ‘slurry’ mixture comprised of abrasive particles and a water/lubricant fluid. A range of polishing pads are selected depending on materials polished.  Other ways use diamond polishing with pellets or tools with diamond paste and for many crystal materials polishing chemicals are used.

Polishing

Optical polishing is used when the requirement is for an ultrasmooth finish with only minimal defects for very specific quality and functionality on optical components. It removes a small amount of material from the surface of the source component, leaving a bright, reflective superfinish or microfinish surface.

This surface will be polished to a certified scratch dig tolerance and a surface roughness. In turn the surface will be polished to a required flatness which could be a couple of fringes or to a more precise flatness of lambda/4 or lambda/10.

Lapping

Where surface material to a greater depth is needed, optical lapping is used and leaves a duller yet high quality smooth finish.

Both polishing and lapping typically follow the grinding process in the fabrication of optical materials such as lenses, windows and glasses. Both processes can be used to produce anything from small batches to hundreds or thousands of optical components with consistent characteristics to achieve exactly the same result.

Optical polishing and lapping can be used for mass processing of large numbers of components in auto manufacturing, aerospace, electronics, optical instruments and a wide range of other OEM sectors.

What is the difference between optical polishing and lapping?

The differences between optical polishing and lapping lie in the amount of material that needs removing from the source optical component and the target characteristics required.

The objective is to achieve specific surface finish, or shape or dimension such as parallelism or flatness. The processes may also be used to achieve combination of these features or characteristics.

Both processes involve the use of a mix of abrasive materials in a lubricant and water-based suspension called a slurry. The material and mix of abrasive particles used in the slurry are adjusted according to the required finish, dimensions or shape of the final optical component.

Additional to a slurry mix, diamond compounds and tools can remove the surface  to a precise micron surface finish.

What is optical polishing used for?

Optical polishing as a process is typically used to achieve specific:

  • Dimensions
  • Thickness
  • Flatness
  • Surface roughness
  • Shape/parallelism
  • Surface quality

Typical polishing examples include:

  • Repolishing to optical glasses with surface damage
  • Polishing of edges to achieve a round or square finish
  • Optical polishing of light guides
  • Flame polishing of rods and tubes.
  • Polishing the surfaces of plano windows and substrates

How is polishing achieved?

UQG Optics can deliver optical polishing of plano windows, plates and substrates from 3mm to 500mm diameter.

We offer double sided planetary polishing on 3-way drive machines capable of delivering large batches, with single sided polishing machines used for diameters of 3mm to 500mm capable of a laser-quality finish up to lambda 10 flatness.

Which optical materials can be polished?

Precision optical polishing can be performed on a range of optical materials including:

  • Optical glasses
  • Fused quartz
  • Fused silica
  • Borosilicate
  • Float glass
  • Filter glasses
  • Silicon
  • Germanium
  • A range of other optical materials

Which optical materials are suitable for lapping?

Materials suitable for precision lapping include:

  • Optical glasses
  • Sodalime glass
  • Borosilicate
  • Fused silica
  • Fused quartz
  • Silicon
  • Germanium
  • Alumina
  • Ceramics
  • Ferrites
  • Other requirement? Please ask.

Precision lapping to both surfaces where tight tolerances are required can be done simultaneously on our double-sided planetary machines. During the process, the component is held in carriers to ensure a stress-free lapping without the need for fixing or clamping.

Do you offer optical polishing and lapping on customer-supplied materials?

Yes. UQG Optics offers polishing on lapping on customer-supplied materials as well as those we supply.

From a single polishing or lapping job to hundreds or thousands of pieces we can accommodate virtually any requirement on a wide range of materials, often completing full batches of precision components in a single day, depending on the material.

The key to success with optical polishing and lapping is consistency in surface quality, dimensions thickness, flatness and parallelism across the entire batch.

Next Steps

To find out more about optical polishing and lapping services from UQG Optics, or any of our other optical services and components call us on 01223 420329 or email our sales team at info@uqgoptics.com