Secrets of Optical Design, Part 1: Understanding Optical Manufacturing

     

secret-1142327_1280This article is the first of a three-part series on aspects of design that are sometimes overlooked in optics courses. Optical design is often as much art as science. However, it is not magic! Like any art or science, skill in the trade comes only with experience and practice. That said, you can save time by learning from the experience of others.

The first step toward becoming an expert optical designer is understanding important aspects of optical manufacturing and assembly. This overview explains some non-optical issues you need to consider when designing an optical system.

Material Availability

Long lead-times are a cruel reality of the optics industry—it can take weeks or even months to receive a component if it is not a "stock" item. Many factors affect lead-time, but the availability of optical materials is often overlooked. The processes for creating various optical-grade glasses and crystals are intrinsically slow. The raw materials can be challenging to acquire. The heating and mixing processes are complex and require constant monitoring. Cooling the super-heated product requires rigid environmental controls. Also, some optical materials are no longer profitable to make. Others have been retired because of ecological concerns. Expert optical designers keep track of shifts in the optical material market and how that affects price and lead time.

Material Science

Optical materials have wide-ranging sensitivities to heat, pressure, abrasion, sheer, and shock. There are also issues of solubility, volatility, and corrosion. All of these "non-optical" material features impact which machining options are available and which operational environments are suitable. Expert optical designers know the chemical and mechanical properties of optical materials.

Manufacturing Methods

There are many ways to manufacture lenses, mirrors, prisms, and flats. The fabrication method must be matched to the materials, tolerances, budget, and production rate. Prevalent manufacturing methods include traditional grinding and polishing, diamond turning, CNC shaping, molding, and new methods in "super-polishing." The methods vary in cost, precision, and production rate. Expert optical designers understand the advantages and limitations of optical manufacturing methods and how those factors affect price and availability.

Opto-Mechanical Tolerancing

It is impossible to design a good optical system without understanding how the mechanical design affects the optical performance and vice versa. Of critical importance is opto-mechanics---the design of mechanical parts to hold optical elements. Opto-mechanics is a distinct field of design, separate from optics and mechanics. Opto-mechanical engineers are skilled in balancing mechanical and optical tolerances to achieve optimum performance and cost. Too often an optical or mechanical engineer attempts opto-mechanical design with disastrous results.  Expert optical designers recognize the critical importance of opto-mechanical design and incorporate the aid of a specialist before finalizing an optical design.

Optical Assembly

The ease of optical assembly significantly impacts the cost of an optical system. Complicated or lengthy assembly processes require extra equipment and personnel. Expert optical designers simplify optomechanical systems and incorporate alignment aids.

Optical designers must understand these "non-optical" issues if they want to design optical systems that work as well in the real world as they do in software. Utilizing the skill and experience of knowledgeable optical designers eliminates pointless iterations on failed concepts. If you find yourself stuck developing a tricky optical system, give us a call. We will either locate the parts you are looking for or suggest options that may be even better.

 Download Our Tolerancing Guide