Free Space Optical Design & Engineering
Zemax, Code V and more...
Free space optics is the area of optics where light propagates freely through space. This is contrary to guided wave optics where light propagates through waveguides. In free space optic design and development, we do use software tools such as OpticStudio (Zemax) and Code V to design and simulate the optical assembly. In our designs we use optical components such as lenses, prisms, beam expanders, polarizers, filters, beamsplitters, waveplates, mirrors...etc. Besides software tools, we do perform laboratory tests using tools such as optical power meters, spectrum analyzers, oscilloscopes, attenuators...etc. to confirm that our free space optic design indeed works as desired. There are numerous applications of free space optics.
- LAN-to-LAN connections on campuses or between buildings at Fast Ethernet or Gigabit Ethernet speeds.
- LAN-to-LAN connections in a city, i.e. Metropolitan area network.
- Free space optic based communication systems are used to cross a public road or other barriers which the sender and receiver do not own.
- Fast service through high-bandwidth access to optical fiber networks.
- Converged Voice-Data-Connection.
- Temporary communication network installations (such as events and other purposes).
- Reestablish high-speed communication connection quickly for disaster recovery.
- As an alternative or upgrade add-on to existing wireless
- As a safety add-on for important fiber communication connections to assure redundancy in links.
- For communications between spacecraft, including elements of a satellite constellation.
- For inter- and intra-chip communication, optical communication between devices.
- Many other devices and instruments utilize free space optic design, such as binoculars, laser rangefinders, spectrophotometers, microscopes...etc.
Advantages of Free Space Optics (FSO)
- Ease of deployment
- License-free operation in communication systems.
- High bit rates
- Low bit error rates
- Immunity to electromagnetic interference because light is being used instead of microwave. Contrary to light, microwaves can interfere
- Full duplex operation
- Protocol transparency
- Very secure due to the high directionality and narrowness of the beam(s). Difficult to intercept, thus very useful in military communications.
- No Fresnel zone necessary
Disadvantages of Free Space Optics (FSO)
For terrestrial applications, the principal limiting factors are:
- Beam dispersion
- Atmospheric absorption, especially under fog, rain, dust, air pollution, smog, snow. For example, fog can cause 10..~100 dB/km attenuation.
- Background light
- Pointing stability in wind
The relatively longer distance optical links can be implemented using infrared laser light, although low-data-rate communication over short distances is possible using LEDs. Maximum range for terrestrial links is in the order of 2-3 km, however the stability and quality of the link is highly dependent on atmospheric factors such as rain, fog, dust and heat and others listed above. Significantly farther distances such as tens of miles using incoherent sources of light from high-intensity LEDs can be achieved. However, the low-grade equipment used can limit bandwidths to about a few kHz. In outer space, the communication range of free-space optical communication is currently in the order of several thousand kilometers, but has the potential to bridge interplanetary distances of millions of kilometers, using optical telescopes as beam expanders. Secure free-space optical communications have been proposed using a laser N-slit interferometer where the laser signal takes the form of an interferometric pattern. Any attempt to intercept the signal causes the collapse of the interferometric pattern.
Even though we have mostly given examples about communication systems, free space optic design and development is very important in many other areas including biomedical devices, medical instruments, automobile headlights, modern architectural illumination systems in building interiors and exteriors, and many others. If you wish, after the free space optical design of your product, we can send the created files to our optical manufacturing facility, precision injection molding plant and machine shop for prototyping or mass production as needed. Remember, we do have the prototyping & manufacturing as well as the design expertise.