U.S. Photonics incorporated in October of 2005. Earlier that same year, we were approached by a medical device manufacturer to provide a solution that addressed specific quality improvement for cutting a titanium alloy called nitinol. Our experience with femtosecond lasers provided us with the opportunity to create a superior machining solution to conventional methods. The technologies we have developed for this industry will be of great benefit for all precision machining applications.

Femtosecond machining has not yet been readily accepted by industry due to the complexity of these systems. U.S. Photonics has addressed these issues including thermodynamics, vibration isolation and control, positioning systems and laser delivery, offering a completely hands-off solution that is simple to use and capable of mass production. The U.S. Photonics system is capable of machining all known materials that exist today including transparent materials and high explosives with unprecedented feature sizes down to 250 nanometers.

• RESEARCH AND DEVELOPMENT
• TESTING AND ANALYSIS
• LASERS, OPTICS, PHOTONICS, DEVICES
• MICRO/NANO MACHINING, LITHOGRAPHY
• MEMS, MICROFLUIDICS, LAB ON CHIP
• SENSORS
• DETECTORS, TRANSDUCERS
• PROTOTYPING
• LAB EQUIPMENT REFURBISHING

Our ultrafast Femtosecond laser here at US Photonics affords us some very crucial advantages over other state-of-the-art laser types. The most notable advantage is the lack of heat transfer during the ablation of a material. Traditional laser machining utilizes laser systems that either operate in a continuous manner or are pulsed on and off on the microsecond (10-6 seconds) or nanosecond (10-9 seconds) timescale. Although these pulses may seem short, they are actually quite long when compared with the time frame of heat absorption (picosecond or 10-12 seconds). If the pulse of light is longer than the timescale of heat transfer, thermal damge may occur resulting in cracking, slag recast, and crystal structure rearrangement.

US Photonics supplied matches whose heads were engraved with our Femtosecond Laser for use as the Fall 2009 cover of Micro Manufacturing Magazine.

Femtosecond or Ultrafast lasers are three orders of magnitude shorter than the timescale of heat absorption (10-15 seconds vs. 10-12 seconds). In this way, femtosecond laser machining avoids the thermal damage associated with traditional machining techniques (laser, EDM, hard tool, etc.) and has the ability to cleanly ablate materials that would otherwise melt, crack or fracture, and even has the ability to ablate highly flamable materials such as the head of a match.

Drawbacks of Conventional Laser Machining Techniques:

• Residual heat and stress around machined area
• Cracking
• Splatter and slag recast
• Sub-surface stress fractures
• Limited to metallic materials
• Feature sizes on the tens of microns

Advantages of Femtosecond Laser Machining:

- Time scale for heat absorption is on the psec scale (10-12)
- Femtosecond laser pulse is 10-15 seconds
- Material is ablated and ejected before residual heat is imparted into the sample:

• No damage to adjacent material
• No splatter or slag recast
• No heat affected zones
• No sub-surface stress fractures
• Sub-micron feature sizes

Are there any disadvantages to femtosecond laser machining?

Due to the precision of the laser and size constraints of the material, Femtosecond laser machining is more time consuming than traditional laser machining. We have, however, discovered several proprietary methods for decreased processing times.

What we mean by Ultra Precise Femtosecond Laser Micro Machining.

Because our femtosecond laser micro machining system yields such smooth cuts, we are able to make incredibly small features, and when paired with our multi axis nano motion stage capabilities, we can output super intricate features in 3 Dimensions, with results depending mostly on how fine a grain that the substrate has. IE - the more fine the grain, the smaller the feature sizes can be.

Past customers have also needed less traditional shapes as well as engravings. Shown above left is a company logo in silver on a quartz substrate. The picture on the above right shows the letter "n" engraved in silver on a quartz substrate. The width of the outline is half the diameter of a human red blood cell.

The versatility of the Femtostation is unmatched. In addition to the mill work shown above, our system can also be used as a lathe. Shown below are pictures of Stainless Steel hypodermic needlestock that was first cut using Electrical Discharge Machining (EDM) on the left and the same needle cut with our Femtosecond Laser Machining technique. Notice the mirror finish of our cut compared with the EDM cut.

Our unique system also allows us to perform additive machinig using Two-Photon Polymerization for true 3-D prototyping. Shown below are concentric rings formed in SU8 on the left and a 100 micron long hexagonal air bridge in SU8 on the right.