The Imaging Source blog

The following is a summary of the article, Vision checks optical characteristics of artificial corneas. The original article, written by Gary Livingstone, was published in Vision Systems Design in July 2016 (Vol. 21, 27-30) and appears here with permission of the publisher.

Thousands of low-vision sufferers could be helped every year with a corneal graft. But with comparatively few donor corneas available, synthetic corneas are a medical necessity. Oxford MEStar, a bioengineering products and solutions company produces such artificial corneas. Gary Livingstone, Managing Director of LG Motion explains in his article, "Vision checks optical characteristics of artificial corneas," how his company developed a semi-automated inspection system for MEStar to tackle a demanding quality inspection task involving these delicate transparent prostheses. LG Motion's vision-based motion control system features The Imaging Source's DMK 23UP031 USB 3.0 industrial camera (USB 3.0 Mono, 5MP, 15 FPS).

Translucency Poses a Challenge to Efficient Inspection

Because the artificial corneas are medical implants, they are of course subject to strict controls. One of the most critical aspects of the control process is the transparency measurement of each cornea which is performed via laser analysis. But exactly this important characteristic, transparency, had made an in-line inspection process problematic. The corneas and their support scaffolds are suspended in a transparent medium in a Petri dish and vacuum packed into sterile blister packs (Fig. 2, below). Locating the transparent cornea within the packaging proved difficult which meant a trained operator was needed to correctly position them for optical analysis in the laser's field of view. Wishing to semi-automate this inspection task as part of an in-line production process, MEStar contacted LG Motion.

Solution: Structured Light and a Monochrome Industrial Camera

An integral part of the vision-based motion control system created by LG Motion is Scorpion Vision's Compact Vision System. In order to differentiate between the transparent substances within each blister pack, the inspected samples are first illuminated by a patterned, red LED (0.25mm grid pattern from wire mesh) (Fig. 3). The built-in USB 3.0 monochrome camera captures the grid pattern image and transmits the image data to the Scorpion Vision Compact Vision System for analysis. The distortion of the light pattern allows the software to identify the edge of the Petri dish thereby creating a region of interest in which the cornea can be found. Edge detection and geometry tools are then further used to precisely locate the cornea. Once the cornea has been detected, the system determines its center coordinates and then optimally adjusts the package in preparation for optical analysis.

Semi-automation for Continuous In-line Inspection

The optical analysis is executed by an Arduino single-board computer which is interfaced to an Arcus Technology stepper motor controller. If the vision system fails to detect the presence of a cornea, or if the analytical system confirms a cornea does not meet the required tolerance, the Arduino processor receives a fail signal and instructs the Arcus controller to move the gripper over to a chute where the defective product is rejected. If the system confirms a cornea meets all requested parameters with a pass signal, the processor instructs the controller to move the gripper over to a chute where the product is accepted. The processor instructs the controller to return to the home position where the next item awaiting inspection can be loaded into the gripper for continuous in-line production.

Learn more about camera options for inspection systems: USB 3.0 monochrome industrial cameras, USB 3.0 color industrial cameras, GigE monochrome industrial cameras, and GigE color industrial cameras or contact us.

Image-based solutions for automatic inspection, process control, measurement and robot guidance, play a fundamental role in the continuing development of automation processes. As many companies make the transition over to the smart factory (Industry 4.0, IIoT and IoT), the question becomes not only what are best practices, but how can companies implement these changes as efficiently as possible? Over 76,016 engineers, system integrators and other automation professionals addressed these themes and Industry 4.0 (IIoT) at the 28th Taipei International Industrial Automation Exhibition 2016 which took place from August 31 - September 3, 2016.

The Imaging Source displayed its 33 series of HDR cameras featuring the highly sensitive Sony Pregius CMOS sensors (IMX264/265/252/174) which are especially well-suited to demanding applications in production automation and quality assurance. Many booth visitors enjoyed a live display of the cameras' features via a Carrera race track. Many thanks to our resellers, Nevis and SureTech, for a great show.

The microscope camera DFK MKU130-10x22 is, to our knowledge, the only camera currently on the market that can be mounted on nearly all microscopes and that can capture the complete field of view, as seen by the observer, without additional optical adapters. The motivation to build this camera came from an oft-posed support question: Why does my C-mount camera only capture a small portion of the image I can see when I look through the ocular? The following images illustrate the situation: ^[1]

Images from C-mount cameras: ^[1] Restricted field of view. These cameras require a lens adapter in order to capture a full field of view:

1. The DFK MKU130-10x22 offers full field of view through the ocular without a lens adapter ^[2].
   Historically, a full field of view from a C-mount objective could only be obtained in conjunction with a lens adapter which in turn had to also be correctly matched to the camera's sensor format. The DFK MKU130-10x22 can be used with nearly all optical microscopes to produce the full field of view observed through the ocular without a lens adapter.
   
   
2. Costly adapter lenses limit your imaging options.
   If, at a later time, one chooses to replace the existing camera with a different C-mount camera having a different sensor format, one would have to replace the adapter lens as well.
   
   
3. High resolution means lower magnifications, larger FOV and an increased DOF.
   The microscope camera DFK MKU130-10x22 has sensor resolution of 4128 x 3096 (13 MP). The key advantage of using the highest-possible resolution is that the microscope operator can select a lower microscope magnification thereby allowing for a larger field of view with an increased depth of field.

[1] Download the original images in this post.

[2] For detailed information about the DFK MKU130-10x22, please see the cameras' product page or DFK MKU130-10x22 Microscope Camera Review by J. Piper and M. Torzewski.

The January 2016 edition of Mikroskopie Journal published a detailed article about the microscope camera DFK MKU130-10x22, written by J. Piper and M. Torzewski.

The article originally appeared with the title:

DFK MKU130-10x22, Modular Microscopy Camera from The Imaging Source - a New Way to a 'Universal Adaptation?'

Over fifteen pages and twenty-one images describe the microscope camera, its mechanical and optical components, as well as the included microscope software, IC Capture.

The conclusion of the extensive test was:

[..] the camera exhibits very good qualities and an equally positive price/performance ratio.

You can download the article as a PDF file, and read the serialized version online.

Summary of Text in Mikroskopie Journal

At the end of 2014, The Imaging Source (Bremen, Germany) brought a new microscope camera on the market with the intention of offering a detachable eyepiece camera with excellent image quality which could be used with practically every standard microscope on the market:

The camera was tested on large-field microscopes from the manufacturers Leitz, Leica and Carl Zeiss Jena with good results, although it must be said that some loss of edge focus occurs at higher magnifications. This reduction of edge focus is caused by the included eyepiece which can, however, usually be exchanged with the original manufacturer's eyepiece.

Even older optical microscopes (e.g. with a cast iron base, mirrors and basic objective lenses with lower field numbers such as the Studio-Mikroskop and Enuro-Optik) and microscopes with non-standardized eyepieces and objective lenses with an even smaller diameter (e.g. the Bresser Biolux AL that was sold a few years ago through grocery stores) could be successfully used. With all of these microscopes, the camera delivered smooth live image display of the real image, video-clips and color images.

A comparison with the Leica camera, MC 170 HD, can be summarized as follows: For routine applications, such as the documentation of bright-field images, the camera from The Imaging Source need not fear comparison with a leading manufacturer's modular camera solution as it pertains to image quality.

Moreover, the authors describe in great detail how the camera's wide-ranging functionality was achieved. This is made possible by a special 5.3 mm focal length autofocus lens which complements the camera's 13 MP Sony sensor and which is further enhanced by a standard eyepiece and an adjustable camera tube. The adjustable camera tube allows for vignette-free illumination and the setting of the eyepoint. With the correct adjustment of the camera tube, the camera delivers the same image the observer would otherwise see through the microscope's eyepiece. The authors especially emphasize the reliable and precise functioning of the autofocus which enables the operator to select and view areas of the image without the need for additional manual adjustment.

The authors also tested the software applications IC Capture, IC Measure and IC Full Screen Presenter. These software products can be downloaded free-of-charge from the manufacturer's website. IC Capture is designed for camera control, acquisition of single images and image sequences as well as videos. With IC Measure, lines, angles, circles and polygons can be measured on-screen and saved. IC Fullscreen Presenter allows for the full-screen presentation of the microscope's live image with an optional foot pedal available.

Originally published in Mikroskopie in January 2016, this article was written by J. Piper and M. Torzewski. The English translation, written by Amy Groth, was serialized into: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11.

Conclusion

With the camera presented here, the manufacturer has made an important contribution to the concept of the 'universal camera.' In comparison to other add-on cameras where upon disassembly an operator could look at the sensor directly, the camera tested here presented a complete and self-contained device - comprised of a lens system, autofocus and small-dimensioned aperture. These components ensure a deep depth of field and efficient correction of any deviations from the ideal focal plane. Which is why, according to our testing, this camera is capable of delivering usable images from diverse microscope designs and manufacturers. The manufacturer-provided eyepiece is made for tubes with an O.D. 30 mm and a fully corrected intermediate image. When the intermediate image is not fully corrected, it is a matter of 'luck' as to how much the residual optical error will cause a visible reduction in quality.

The camera's universal application is further supported by the fact that the camera is not limited to its own eyepiece but can also be used in conjunction with the original eyepieces of various microscope manufacturers. In this way of course, the problem of the uncorrected intermediate image is avoided altogether by combing the camera with the original compensating eyepiece.

The camera sensor has proven itself very efficient; it can indeed 'keep up with' the sensors from much costlier and more complex designs of leading microscope manufacturers.

When the complete field of view needs to be imaged, it is a disadvantage that the edge focus of the included eyepiece is less than ideal. For images with perfect edge focus, only the middle two-thirds of the field of view should be used. Other Plan-corrected large field eyepieces from leading manufacturers can - also in combination with the camera - deliver visibly better edge focus.

A real 'highlight' is the averaged and selective autofocus. This works so quickly and accurately that it delivers reproducible precision in image focus which (depending on the eye) could be seen to rival, or even be superior to, subjective visual focus.

All in all, the camera offers excellent features as well as an excellent price-to-performance ratio.

With regards to the video function, it could be discussed if a video recording via standard camera or video camera might be advantageous since, as a rule, these easily produce real-time images on the monitor even while recording in color at full HD and additionally require less disk space than the AVI format. As a positive side effect it should be noted that the camera as such, outside of its application in microscopy, can also be used for photos and videos which feature excellent depth of field and whose quality (especially in close ups) is more than adequate for simple documentation purposes. According to our tests, the camera could even prove itself useful for some medical applications such as the quick documentation of wounds and other changes in the skin or as a dental camera.

Constructive Suggestions for Further Development

It would be desirable, if the camera came with even higher performance eyepieces with less field curvature than the Meiji eyepiece with which is currently equipped. Additionally, it would be suggested that several camera tubes of various or variable (i.e. adjustable) diameters be made available. This could be accomplished with relatively little effort since these are merely cylindrical tubes with a standardized screw thread. This would enable the customer to acquire a tube whose diameter properly fits their eyepiece head / eyepiece or which is made to adapt with fewer necessary adjustments. Because the software offers extensive options to manually adjust a multitude of parameters, a suggestion would be to integrate a 'reset' function which with one mouse click would return the software to standard default settings.