Spherical Lenses—also known as optical spheres—are lenses shaped in the form of a partial or complete sphere. The design of such lenses allows light passing through the edges to come to a focus at a closer distance to the center of the lenses than the light passing through the center.

Types of Spherical Lenses

There are several types of spherical lenses available, each of which demonstrates different qualities that make it suitable for use in different applications. Five of the most commonly used types include:


These cylindrical lenses are suitable for focusing, collecting, and collimating light to a single line. Their asymmetrical design helps minimize spherical aberration—i.e., loss of image definition—in applications involving an object and image placed at unequal distances from the center of the lenses. They serve as a cost-effective lens option for demanding operations.


Similar to plano-convex lenses, bi-convex lenses have positive focal lengths. When used in applications involving objects and images positioned at equal or near-equal distances from the lens and/or with conjugate ratios between 5:1 and 1:5, they minimize spherical aberration.


In contrast to their convex counterparts, plano-concave lenses have negative focal lengths. They cause light to diverge as it passes through to the output side. The ideal setup for these lenses is a situation in which the object and image are at conjugate ratios greater than 5:1 and less than 1:5. Due to their negative spherical aberration, they can be used to balance out other lenses.


Similar to plan-concave lenses, bi-concave lenses have negative focal lengths. They are suitable for applications that require collimated incident light divergence, light expansion, or increases in focal length, particularly if the object and image are at conjugate ratios near 1:1 with converging input beams.

Positive Meniscus

These lenses are generally used in applications with smaller f/numbers (2.5 or less). They are specially designed to minimize spherical aberration and can be used to tighten focal spot sizes, shorten focal lengths, and increase numerical aperture if used alongside another lens.

These spherical components play a key role in a wide range of industrial devices, equipment, and systems that employ optical technology, such as otoscopes.

What is an Otoscope?

Otoscopes—sometimes referred to as auriscopes—are medical tools used by healthcare providers to look into the ears of patients to view the area from the outer ear through the ear canal to the eardrum. They are generally employed to screen for illness as a preventative measure or to investigate potential ear-related illness symptoms.

These medical devices can be categorized into one of three major classifications:

Pocket otoscopes

Pocket otoscopes are smaller and more lightweight than other types of otoscopes. They are designed to fit in small or tight spaces, such as in the pockets of medical professionals, and tend to rely on the use of alkaline batteries for handle power.

Full-size Otoscopes

Compared to pocket otoscopes, these otoscopes are bigger and heavier. They are available with interchangeable head and handle options that can be purchased individually for improved functionality.

Video Otoscopes

These otoscopes are capable of interfacing with computers and monitors. They can be used to project, capture, store, and email high-quality images and video of a patient’s ear.

How Do Otoscopes Work?

The basic design of an otoscope consists of:

  • A long—often textured—handle for the healthcare provider to hold while performing patient examinations
  • A bright light source to facilitate inspection of the dark and enclosed ear canal and eardrum
  • A magnifying lens—typically a spherical lens—to enhance details within the ear

Combined, these three components allow healthcare providers to screen patients for any ear-related issues.

Partner With Optics Technology For Quality Spherical Lenses

Otoscopes and spherical lenses play a crucial role in the preventative maintenance and treatment of ears. For industry professionals that need replacement spherical lenses for their otoscope, the team at Optics Technology can deliver.

At Optics Technology, we offer a comprehensive range of manufacturing services aimed towards manufacturing high-quality custom micro and miniature optical and optomechanical components up to 30 millimeters in size, including spherical lenses. Our capabilities include:

  • Optical design and fabrication
  • Mechanical design and fabrication
  • Assembly
  • Testing

Customers in the aerospace, biomedical, design engineering, healthcare, microscopy, and research markets regularly employ our services to produce custom lenses that meet their exact needs.

For additional information on our custom spherical lenses, contact us or request a quote today.

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