More cameras, more pixels, more sensitivity, more choices...

Leica Microsystems Pty Ltd
Wednesday, 08 August, 2001

Since the beginning, microscopists in their investigations and endeavours have been bound by the limitations of their instruments. These limitations are further complicated by the requirements of the specimens studied. Before any examination can begin, the microscopist must provide optimal conditions in order to gather accurate information about the subject. These conditions may include special requirements for illumination, temperature or may include time constraints. It is no wonder that the demands on photography in the field of microscopy can be particularly challenging.

In the past, traditional photography in conjunction with microscopy has helped us make and record remarkable discoveries and understand the unknown. The long history of conventional camera use in this field demonstrates this. The recent explosion in information technology and discovery of digital photography has opened a new era in scientific imaging. Thanks to this technology, scientific progress has been accelerated.

While conventional photography still offers the advantages of ultra high resolution, large tonal range and excellent colour reproduction, users have always been plagued with the complexities of the photographic process. The time and material wasted in obtaining a useable image has always frustrated scientists. Even once these images are obtained, problems arise with regards to their storage, handling and reproduction.

The only disadvantage of digital photography is that its resolution is comparatively low, a temporary problem, which will be overcome in future product developments. This minor inconvenience is eclipsed by the immediacy of digital image capture, ease of replication and storage. The beauty of digital photography is that it has removed the need for the scientist to be a photographic expert. It has also put image replication and enhancement (traditionally the domain of photographic specialists) into the realms of the lay-user.

All there is to see about the CCD

The CCD (Charged Coupled Device) is the light sensor in a digital camera and is a very important element. The CCD picks up the changes in light on its light sensitive matrix. The picture is composed by the CCD's interpretation of the picture elements, or pixels. The more pixels available to form the image the more detail you can see. But more pixels are not necessarily better and the number of pixels squeezed onto a chip is a compromise between chip size and pixel size.

What about colour depth?
Well the measure of tonal range in a pixel is its bit depth. More bits do deliver more colour but you should consider the fact that the display media may not show this, so ultimately you would not even see the difference.

For instance an 11-bit dynamic range is more than film, print media or a PC monitor can display as well as being more than the human eye can differentiate. Unfortunately, the trend is for customers to select cameras by the number of pixels and bits, rather than comparing the pictures they would take.

The main question the user should be asking is what the images are required for. As already mentioned, digital photography should not be a replacement for conventional photography if the same resolution is expected. On the other hand, if the user requires a system for quick and convenient image capture in microscopy for archiving, retrieving, sharing and transmitting, then super high-resolution images would be a hindrance anyway, being large file sizes they would be hard to move, email, copy and process.

Transmission speed
An important thing to look for in a digital camera is the speed at which the image is transmitted to the computer. The faster this transfer occurs, the higher the possibility of seeing a live picture. This will assist in framing white balance correction and critical focusing. It's a good indicator that the camera is too slow if the user has to spend time adjusting the image away from the scene.

Just as researchers' applications are varied, so are their requirements for photomicrography. For example, the Leica DC300 matches routine brightfield microscopy requirements in busy laboratories where pictures are captured quickly with high resolution. Its fast image repetition rate delivers the display almost in real-time and coupled with its 3.3 Megapixel CCD it gives a sharp and brilliant result. The requirements of fluorescence microscopy are slightly different.

Fluorescence photography

Fluorescence photography presents special demands on the equipment and its operation. Negligible light intensities call for state-of-the-art electronics, which can use all available light to acquire a clear, precise image. To obtain optimum images, a long integration time should be offered for weak fluorescing objects together with high linearity over the whole light intensity range.

Some cameras cool for CCD for low-light applications; this is not always necessary to achieve excellent results. Special software packages are also required for fluorescence imaging, such as the ability to assign the correct colour to each received wavelength.

The Leica DC300F and 350F cameras have been designed specifically for fluorescence photography in conjunction with the IM1000 Image Superimpose Module, whilst the Qfluoro Analysis Software is fit for the more demanding requirements of fluorescence microscopy.

Digital microscope cameras

Complex applications too, demand high precision performance from optics, electronics and software. Technology where even the finest structures need to be reproduced and assessed with accuracy calls for special image capturing equipment, such as the Leica DC500 where exposure times of up to 500 seconds can be achieved. And together with its four individually selectable resolutions from 1.3 Megapixels (1030 x 1300 pixels) to 12 Megapixels (3090 x 3600 without colour or pixel interpolation) delivering perfect image capture of both dark and bright areas and colour quality without noise, makes for an impressive system.

The versatility of the DC500 offers greater efficiency in scientific photography and microscopy in industrial image recording.

Image management software

Image enhancements and corrections are now possible within sophisticated, tested and proven image management softwares, for example Leica's Image Manager, Qwin and QFish. Images can be efficiently enhanced, processed, deleted or reused. The software provides users with a multitude of options for image measurement, comparison, multifocus processing and presentation. Once perfected, images can be easily replicated, printed, stored, shared and inserted into documents.

To meet the increasing demand for image-capture systems, Leica Microsystems introduces this competitive and comprehensive new product range to cover all applications and budgets.

The CCDs of the Leica cameras have been designed with the specific requirements of the microscopist in mind. The C-Mount fittings on all of our compact camera heads ensure ease of use. Our modular design offers not only the right camera for any application but also the right software. We understand our customers' applications and strive to make them more successful in their research.

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