The Scheimpflug principle states that for a plane (such as a camera lens) to remain in focus on an object, the plane of focus must be parallel to the image plane, and the plane of the lens must be angled so that it intersects the plane of focus at a specific point....
A dispersive prism is an optical element used to break up light into its different wavelength components - a phenomenon discovered by Sir Isaac Newton. By doing this, the prism separates light of varying wavelengths, with longer wavelengths (red) deflecting at a...
Plano convex lenses are lenses with a positive focal length and while they are simple compared to many optical systems, but there are fine details that a lens designer needs to pay attention to. This post will review 3 key rules for designing a plano convex lens
One parameter that can be used to evaluate the quality of a laser beam is what's called a Beam Caustic. A caustic, in general, is an “envelope” that defines the extent of a beam of light after they have been refracted (or reflected ) by a curved surface. As the...
When working with lasers it is important to understand the physical parameters that define system performance. Some of these specifications may be more familiar than others. For example concepts like wavelength and divergence are commonly used when describing the...
Parabolic mirrors are optical systems that are used to collect or distribute energy. They have a wide range of applications from solar collectors for water heating systems to microscopes and telescopes, and everyday flashlights. The most common way ...
In an achromatic lens design, we optimize such that two wavelengths, usually red (590nm) and blue (495nm), focus on the same image plane. This is done to reduce chromatic aberration. In this article, we’ll talk about a similar design type called an Apochromatic lens...
A previous post discussed underwater optical design. This week, we will review the diametrical opposite application - free-space optical communication (FSO). As with underwater optical design, one of the challenges facing FSO is the optical signal propagation...
In a previous post, we explained the concept of a material refractive index in optics in the context of optical design. Something that we didn’t review however is that many materials have two, three (and even more) different refractive indices depending on the...
As mentioned in several articles in this blog, aberrations are of great relevance when designing an optical system. The objective being to design a system that creates a “good image”. However, there are different metrics to evaluate what is a “good...
One important aspect of any design is user safety. This is especially important when using light sources like lasers and LEDs that may be observed by the naked eye. Disregarding safety can lead to product recalls, lawsuits, and harm to users. To protect users, a...
A 4f correlator optical system is a system architecture that uses Fourier Optics. In this article, we will explain why we need them and how to design a simple 4f correlator. We will leave out most of the mathematical derivations, but if you are interested...
As optical engineers, we use different tools and techniques to evaluate the performance of an optical design when simulating the system in a ray tracing program. One of those tools are spot diagrams. They may be a little bit confusing to use at first but are an...
Filters for selecting specific wavelengths are common in optical systems. In our microscope design article we explained the use of dichroic mirrors to select fluorescent wavelengths. In some applications optical engineers need to filter out high (UV light)...
Introduction The refractive index is one of the basic concepts in optical sciences. Same as volume, and density, the refractive index is a fundamental property of all materials. However, not only materials that are used in optics have a refractive index. For example,...
One of the most famous images in the history of optics is that of Sir Isaac Newton with a beam of white light going through a glass prism and a rainbow coming out the other side. It is one of the most famous optical experiments, not only for its simplicity, but also...
A Strehl ratio is used to define the quality of an optical system by showing how a real optical system compares to an ideal aberration-free system. The Strehl ratio incorporates the Point Spread Function (PSF) and its relation to wavefront aberration of the optical...
Depth of field is a distance range where the image optical resolution is as high as possible for that lens, i.e. an image appears to be in focus. When starting a lens design program, having a good understanding of this parameter’s physics will help you and your...
Optical invariants are mathematical expressions representing several optical parameters. The values for each optical invariant are constant despite the fact that optical parameters change from one part or element of the optical system to another. Optical invariants...
