Plastic Optical Machining by Controlled Fluidics

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ABOUT OUR OPTICAL PLASTIC MACHINING & POLISHING

We manufacture optical-grade plastic parts manifolds for analytical, industrial, medical/bio-medical, and life science applications. From entire components to singular bio-detection windows, we work to support your design requirements. Our experienced machinists know how to remove imperfections, scratches, and other surface irregularities that result in better transparency and light transmission than other materials.

For low to no diffraction applications, the optical machining process is the best choice for performance. Our optical machining processes allow the end user to have clear visual inspection capabilities via the product. Engineers typically integrate products with UV-Visible, Near Infrared and FTIR spectroscopy instrumentation for easier monitoring, control, and analysis.

BENEFITS OF OPTICAL GRADE PLASTICS

Lighter Weight

Plastic optics typically weigh in about 3x lighter than glass optics. As a result, this gives a distinct advantage when components need scaling into larger pieces.

Improved Visible Light Transmittance

Optical plastics cover a breadth of light transmittance, e.g. acrylic transmits light more fully than most optical glass (94% range).

Cost Effective

While size, complexity, and the raw material itself play a part in total cost, optical plastic products result in meeting tighter budgets better in most cases.

Tougher & Safer

Some materials are far less likely to fail under impact loading than a similar-size glass lens. If damaged, plastics produce substantially safer-to-handle shards than glass.

Increased UV Transmission

In applications requiring ultraviolet and near infrared transmission, plastic lenses often perform better than optical glass.

Post Production Processes

Optical plastics can take further enhancements even after completing the polishing process. This includes coating and assembly.

OPTICAL POLISHING TECHNIQUES

After removing larger imperfections and preparing the product's surface, machinists use one or more of these methods to polish plastics to optical-grade clarity.

MECHANICAL POLISHING

As the most commonly used method, staff use compounds, abrasive pads, or other tools to remove material from the product's surface in a controlled manner. This method removes imperfections and creates smoother surfaces through a more manual method.

CHEMICAL POLISHING

Instead of using mechanical means to polish, machinists use specialized solutions and chemicals to dissolve gently a thin layer of material. This method can leave a smoother surface than other techniques used, depending on the machinist's skill and experience.

ULTRASONIC POLISHING

This unique method uses high-frequency ultrasonic vibrations from a specialized tool to aid in smoothing surfaces that require finesse. Some products need more precision because of their necessary detail to make the end product not only functional but successful.

OPTICAL CLARITY GRADES

Here are 4 levels of clarity we recommend every designer and engineer considers when creating products with optical purposes.

GRADE 1:

AS MACHINED/"AS IS"

This is the standard finish for machined plastics. Surface roughness is better than 32 micro-inches (.8 microns). Surfaces range from translucent to opaque depending on the feature geometry and cutting conditions. This is appropriate for non-visual applications.

GRADE 2:

TRANSPARENT/CLEAR FINISH

This finish allows for activities like visual fluid flow and bubble detection. Most designers and engineers choose this grade as it tends to meet a broad range of design requirements. It's the mostcost-efficient method with limited quantitative measurements for quality when polishing for the entire part. We recommend vapor polishing as most appropriate for this type of clarity. However, we caution that products can vary in haze and clarity here. Tool marks and some scratches can be present but do not affect overall functionality.

GRADE 3:

WINDOW-GRADE CLARITY

We recommend this grade for imaging via manifold or for detection sensors. To the unaided eye, Grade 3 looks similar to window glass. Instead of applying to the whole product like Grade 2, operators apply this in a localized area like beneath an optical sensor. With this grade, products have few visible scratches and tool marks, if any. To achieve this clarity, we recommend specifying a surface finish of less than 2 micro-inches Ra (.05 microns) for the planned product.

GRADE 4:

TRUE OPTICAL CLARITY

This is a true optical finish specified in both surface finish and surface form. We recommend this level of clarity appropriate for lenses, but we don’t find use typically in manifold applications. We measure our surface finish and form for optics with a white light interferometer. For surface finishes, we specify in angstroms its thickness. Regarding surface form, this aspect represents the surface's waviness and its adherence to the ideal profile. We measure form in fringes here.

Optical manifold applications allow for

Visual inspection,
Bubble detection,
Cell identification, or
Fluid processing.

In many cases, the optical manifold has a clear window above the working fluid (typically a channel section or larger chamber), allowing for real-time analysis. Usually, a manifold’s detection system is mounted close to the optically transparent sample chamber for monitoring, control, and analysis. Engineers typically integrate UV-Visible, Near Infrared and FTIR spectroscopy instrumentation within these optical channels for enhanced visibility and better, more conclusive results from analysis.

For example, flow cytometry makes great use of optically clear manifolds and machined parts. The optical plastic manifold allows for cells or particles analysis as they flow past detection lasers in a salt-based solution. Analysts then investigate the light scattering through the scopes, referring to specific parameters related to the target particle. Other applications include gene sequencing, IVD, point of care, cell counters, and blood analyzers.

BEST PLASTIC MATERIALS FOR OPTICAL MACHINING

We meet the strict standards set through USP Class VI (6) and the FDA for approved food-grade plastic materials to use for optical purposes. As these materials also come in biocompatible grades approved by these governmental bodies, we can recommend the following materials:

A NOTE ON DESIGN HERE

Design requirements specify a square or round channel of appropriate size for highly polished surfaces. Expect the surface finish to be better than 2 micro-inches to avoid diffraction of the laser or UV light source.

OPTICAL MACHINING & POLISHING