Olympus and Grundium have joined forces to enhance the implementation of digital pathology technologies in diagnostic and research laboratories. Olympus Corp. (OTCMKTS: OCPNY) is a leading manufacturer of optical and digital precision technology, designing and manufacturing microscopes for over 100 years. Olympus’ revolutionary products include X Line objectives, which are developed using a proprietary manufacturing technology.

Grundium, a Finish company established in 2015 by ex-Nokia engineers, has recently incorporated Olympus’ high-performance X Line objectives into its Ocus® line of portable microscope scanners to facilitate the generation and sharing of high-quality digital pathology images.

With the release of Grundium’s Ocus scanners, Olympus has widened its range of digital pathology solutions. By levering complementary expertise in digital imaging and microscopy optics, this collaborative effort aims to make remote consultations by pathologists more accurate, flexible, and faster.

Conventional objective lenses: a tradeoff between image resolution and field of view

Objective lenses play a decisive role in the performance of microscopes, unquestionably the most essential tool used by pathologists. Ideal microscopes produce high-quality images with a large field of view and image flatness.¹

However, the performance of conventional objective lenses is limited by the tradeoff between chromatic correction, image flatness, and numerical aperture. Hence, improvements in certain image characteristics lead to deterioration of another property or speed of imaging.¹

Although pathologists can choose the objective lenses with properties that best suit their imaging needs, there is the imperative need for objective lenses with improved characteristics in various areas, as the acquisition of high-resolution images in only a narrow area can impact the accuracy and reliability of image analysis and, thus, of diagnosis.

X Line objectives offer high-quality imaging over a large field of view

By leveraging an innovative manufacturing technology, Olympus has recently developed X Line objectives. These advanced objective lenses offer superior optical performance with a high numerical aperture without compromising other aspects of the optical performance.² The high numerical aperture of X Line objectives enables the acquisition of images with improved resolution, depth of focus, and brightness due to the increased ability of the objectives to collect light. Objectives with large numerical aperture are particularly important for the imaging of samples with very fine structures.³

Furthermore, Olympus’ X Line objectives have improved image flatness—which is often limited by light aberrations and artifacts due to field curvature. Especially for applications requiring high image quality over a large field of view, image flatness is critical for the accuracy and reliability of quantitative analyses (e.g., expression levels of different biomarkers) of pathology images.²

In addition to higher numerical aperture and improved image flatness, X Line objectives also offer an expanded range of chromatic correction. Chromatic aberration due to light reflection and the limited ability of objectives to focus light of different wavelengths in one spot can significantly impact the quality of images.³

Correcting chromatic aberration in microscopy is key for acquiring images with high resolution and improved quality. The chromatic correction of conventional objective lenses ranges between 430 and 660 nm. This limited range of chromatic correction causes colocalization issues for the focus position of light with wavelengths shorter than 430 nm and longer than 660 nm. In contrast, the chromatic correction of X Line objectives is broader, ranging between 400 and 1000 nm.²

These unique properties of X Line objectives allow them to generate high-quality digital pathology images with high resolution, optimal brightness, a large field of view, and improved color accuracy.

The advanced manufacturing technology behind X Line objectives

In contrast to conventional objectives engineered to have a high numerical aperture at the expense of image flatness and chromatic correction, Olympus’ X Line UPLXAPO60XO objective has a numerical aperture of 1.42 while offering improved image flatness and increased chromatic correction. For comparison, most conventional microscopes have numerical apertures ranging from 1.0 to 1.35. This is possible due to a novel proprietary lens manufacturing technology, which allows the production of ultra-thin concave objectives and of convex objectives with ultra-thin edges.²

These unique characteristics of objective lenses enable the acquisition of light at a broad angle. Additionally, because lenses are ultra-thin, each objective can be equipped with more lenses, contributing to the high image flatness, numerical aperture, and chromatic correction range of X Line objectives.³

In addition, the possibility to combine several convex and concave lenses with different refraction indices in the same objective improves the ability of microscopes to improve optical aberrations in images.³

To increase the image flatness of X Line objectives, Olympus developed a method to manufacture lenses with a small Petzval sum—which describes the inability of a lens to bring a flat object into focus on a flat image plane. Lowering the Petzval sum is achieved by having thin center concave lenses and increasing the distance between concave and convex lenses. The improved image flatness of X Line objectives enables the acquisition of uniform and clear images throughout the field of view.²

Furthermore, Olympus’ advanced lens polishing technology allows the manufacture of objectives combining multiple convex and concave lenses so that light of different wavelengths can be focused on the same spot. This expanded range of chromatic correction provides the possibility for the acquisition of crisper images and accurate microscopy data.²

Outlook: combining high-performance objectives with digital technologies to advance digital pathology

With this partnership between Grundium and Olympus, Ocus scanners offer a novel, cost-effective telepathology system that can accelerate digital pathology workflows by facilitating remote pathology consultations.

The instrument is easily portable and can be used by pathologists to scan slides and share digital pathology images from any location. The high speed and flexibility of Ocus scanners enable remote review of pathology samples, accelerating diagnosis.

The improved image flatness of X Line objectives makes them ideal for whole slide imaging as they can efficiently produce tiled images with high quality over the entire field of view.²

Moreover, the acquisition of high-quality raw imaging data using advanced objective lenses facilitates the conduction of quantitative analyses with high reliability, accuracy, precision, and reproducibility.

In addition, the high optical performance of Olympus’ X Line objectives integrated into Ocus scanners facilitates the generation of high-resolution digital slide images, increasing the accuracy of diagnosis.²

To learn more about Ocus single slide scanners integrating X Line objectives, refer to the white paper by Masahiro Sakakura, “X Line Objectives Offer Revolutionary Optical Performance Thanks to Advanced Manufacturing Technology.”

References

1. Chen X, Zheng B, Liu H. Optical and digital microscopic imaging techniques and applications in pathology. Anal Cell Pathol. 2011;34(1-2):5-18. doi:10.3233/ACP-2011-0006
2. Sakakura M. X Line Objectives Offer Revolutionary Optical Performance Thanks to Advanced Manufacturing Technology.
3. Chandler R. 3 Advantages of Using X Line Objectives. https://www.olympus-lifescience.com/en/discovery/3-advantages-of-using-x-line-objectives/. Published 2019. Accessed August 19, 2021.