Science photography

This week I thought I’d have a look at a microscopic imaging and its scientific uses – an area of imagery that is highly specialised in that the equipment is very technical and can only be done in certain labs, as well as that there is such a vast array of things that are too small for the human eye to pick up and when viewed under a microscope can dazzle and amaze. This type of photography is often referred to as ‘science photography’.

Light-field microscopy

Let’s get geeky
This is the simplest of the microscopy techniques, where the sample is illuminated from below with white light and the sample absorbs this light, creating contrast. There are 3 main components: a light source, condenser lenses that focus the light (more lenses for more magnification), and an eye piece (or ocular) to view the sample. The samples are sometimes manipulated, such as using stains, to enhance the target object.

Let’s get practical
As this is the most common form of microscopy, it is used in all laboratories across the world. It can be used to identify DNA, to examine cell organelles such as mitochondria to cells dividing in real time.

Let’s get creative
As imagery of this type is becoming more and more common (you can acquire a relatively decent microscope with a camera fitting for a good price these days) the art lies in preparing your sample more than anything else.

Aegagropila linneai, also known as Marimo

Aegagropila linneai algae under the light microscope

Stained locust DNA

Stained locust DNA under the light microscope

Yanping Wang, Honorable mention in the Nikon Small World Competition 2011

This is how the pros do it, like Yanping Wang from the Beijing Planetarium. Click on the photo for more of his images. 


Dark-field microscopy

Let’s get geeky
This is an alteration of the classic light microscope, where a black patch is used to exclude direct light, and only scattered light is seen – a diagram might help illustrate this principle.

Let’s get practical
Because this type of microscopy creates more contrast than simple light microscopy, it is very useful to illuminate unstained samples that have lots of smooth surfaces. Colours will often become very enhanced and look more beautiful than against a white background, but as it is a simple switch on a single microscope, it is easy to test a sample in light and dark field microscopy. Strangely enough this technique has also been used in computing to allow an optical mouse to work on transparent glass.

Let’s get creative
This type of imaging is much more vivid in colour and is therefore preferred when taking photos for the sake of photos rather than research.

Daphnia under under dark-field conditions

Daphnia under under dark-field conditions

Dinoflagellates under the dark-field microscope

Dinoflagellates under the dark-field microscope

Wim van Egmond honorable mention Nikon Small World 2011

Very spacey this Argulus fish louse! Wim van Egmond works at the Micropolitan Museum in Holland. Click on the photo to see more of his work.

Geological microscopy

Let’s get geeky
This is another alteration of a traditional light-field microscope, where polarising filters are used to change the angle at which light hits the object, allowing different properties of your sample to show itself, not plainly visible to the naked eye. As the key word is ‘angle’ the plate to which you attach the sample rotates, and by spinning it around you will actively see the colours change.

Let’s get practical
A material that changes colour under such a filter is ‘birefringent’, and there’s not so many that are – it’s mainly used for rock and mineral samples (hence the name). Other materials that exhibit these properties include plastics and cotton. And in medicine it can be used to examine stained amyloid plaques, a feature of Alzheimer’s patients’ brains.

Let’s get creative
Although limited uses, the samples do always look stunning and you might find new material that display birefringent properties – such as this previous post on honey.

Honey under the geological microscope

Honey under the geological microscope

Fluorescence microscopy

Let’s get geeky
Instead of measuring the reflected light by a sample, this technique measures the amount of fluorescent light emitted by a sample. To do so, a specific wavelength of light is used that will then excite fluorescence, which is at a longer wavelength than the light used to illuminate the sample. Special filters are used focus the light and exclude unwanted light.

Let’s get practical
The sample must be fluorescent first, which usually involves using fluorescent stains or expressing a fluorescent protein. This technique is used to detect specific cell nuclei or fibres, uses antibodies and antigens to detect specific molecules or changes proteins which allows them to be tracked in live cells.

Let’s get creative
Although this technique is quite complex in terms of sample preparation, the result is highly rewarding and produces some fantastic images.

Thomas J. Deerinck - HeLa cancer cells, Nikon small world 2011 12th place

Thomas J. Deerinck works for the University of San Diego in their microscopy and imaging research department. This stunning shot of cancer cells was taken using 2-Photon fluorescence.

Marta Guervos honorable mention Nikon small world 2011

Marta Guervos is an imagers at the University of Orviedo in Spain. This image is of silver wattle pollen grains and eliciting auto fluorescence, and was an honorable mention in 2011’s Nikon small world competition.

Transmission electron microscopy

Let’s get geeky
This equipment is very big and very expensive, both in cost and maintenance. Therefore this is much less common than the above techniques for creative imaging purposes. As the name suggests, electrons are transmitted through a very thin sample, and the resulting image shows the interaction of electrons with the specimen. As the vacuum in such machines is very strong, the samples also need special treatment in advance. The magnification is far greater than on light microscopes, up to single columns of atoms at over 10o,000s times magnification.

Let’s get practical
Information gained from this technique is in morphology, topography, composition and crystalline properties. This technique is used in virology, distinguishing healthy from diseased tissues, as well as determining the structure of the bacteria that cause these diseases. Insulin, a liquid crystal, is studied under a TEM microscope to diagnose diabetes. It is even used in computer and silicon chip development to perform semiconductor analysis.

Let’s get creative
Images of this sort tend to be quite flat, and because of the cost involved, are not as commonly used in creative imagery.

TEM x 12000

I can’t remember what this specimen was but I love that this organelle looks like a bear. Taken at 12000x magnification

Scanning electron microscope

Let’s get geeky
Electrons are used for scanning this time (surprise!). A focused beam of electrons scans the sample, and the signals detected give information about the topography and composition of the subject – which is why this technique will almost always give impressive images that look 3D. Most specimens are scanned in a vacuum, requiring them to be dried but special environmental SEM machines can observe the specimen in wet conditions too. Magnification can get up to 500,000 times life size.

Let’s get practical
For a long time specimens needed to be desiccated (and plated with gold to increase conductance) before placing under an SEM, which meant that its uses were restricted, but in the 1970s the first images of wet SEM specimens were produced. It is widely applied across many disciplines of science, from imaging the adhesive used by marine algae to gunshot residue analysis in forensics and materials analysis to detect its sensitivity to surface potential.

Let’s get creative
As mentioned before, this type of imaging, because it is also expensive, is not as widely performed as light microscopy, but the results always look spectacular. Traditionally images are black and white, so post-processing is required, the limit of which is your own imagination!

pre-peach-SEM

This is how the image comes out of the SEM machine, and is completely un-processed. This is a peach skin.

peach-SEM

This is the same image with very simple colour added to it in photoshop.

lacewing larva Igor Siwanowicz winner Nikon small world 2011

And this is the cream of the crop. This image of a lacewing larva won the Nikon small world competition in 2011, by Dr. Igor Siwanowicz of the Max Planck Institute of Neurobiology. Again, click on the image to see more of his work.

Nikon small world competition
The biggest celebration of imagery at a microscopic scale is the Nikon small world competition, aiming to promote the beauty of life at a microscopic scale, both in still photography and video (named small world in motion). The 2012 winner was a Christmas light-esque image of a zebrafish embryo’s blood-brain barrier, and the video was a film of the injection of ink into a yolk sac artery of a chick embryo to visualise the beating heart.

Advertisements

One thought on “Science photography

I'd like to know your opinion too

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s