The microscope

Specimen Illumination

Using the correct illumination for your specimens is critical for getting the best images for your visitors.  Each specimen has its own unique physical characteristics and may require different lighting techniques.

Tags: Microscope techniques

  • Top Illumination

    Many specimens will be “opaque” and unable to let light pass through, such as many rocks, fossils, circuit boards, thick textiles etc.  In these instances light coming from above will be the most appropriate way to observe specimen detail.  DISCOVERY has a top light built into the microscope arm.  It is positioned on the arm at such a height so as to produce general purpose “oblique (angled)” lighting and creates some relief and shadow on specimens.  Pushing the microscope’s black three way switch to the “up” position turns the built-in top LED spotlight on and this will be adequate for highlighting features of most opaque/solid specimens.

  • Top illumination and background colour

    It is also very advantageous to control the background colour for some of your specimens when using top illumination.  The microscope’s camera is sometimes challenged by trying to correctly image particularly small specimens that may be very light or dark in colour against a very light or dark background.  In these instances we strongly recommend the experimentation of alternative background colours (e.g. light-mid grey, light blue, etc.) that you can place your specimens on.  The microscope’s camera will provide an improved image in these instances.

    If the universal plinth is ordered, it is supplied with two types of stage plate.  One is a clear acrylic type while the other has a grey tint.  When using the plinth in its bottom illumination setup (light transmitted through the specimen), we recommend using the clear stage plate.  When using top illumination, we recommend you experiment with the clear and grey tint stage plates.

    The images to the left (crushed shell) are taken from DISCOVERY with optional universal plinth fitted and top illumination selected.  The first image is taken with the clear stage plate fitted (producing a light background).  The second image is taken with the grey tint stage plate fitted (producing a darker background).  The microscope’s camera is better able to produce an image with improved contrast and illumination of the crushed shell.

  • Transmitted (bottom) Illumination

    Many specimens are transparent or translucent and are able to let light pass through, such as many leaves, feathers, pond life, thin textiles, paper, thin rock, plant and tissue samples on microscope slides.  In these instances light coming from below (transmitted) may well be the most appropriate way to observe specimen detail.  The optional universal plinth, with its high intensity LED array, provides the transmitted light necessary for highlighting features on these specimens.  Pushing the black three way switch to the fully “down” position turns the transmitted light of the universal plinth on (if you have the universal plinth fitted).  Our optional polarising attachment also utilises the universal plinth’s transmitted light.

  • Combining incident (top) and transmitted (bottom) illumination

    Some specimens that are transparent or translucent may benefit from both incident (top) and transmitted (bottom) illumination at the same time.  Such examples are leaves, textiles, paper etc. but there are many more.  DISCOVERY allows for this – pushing the microscope’s black three way switch to the middle position will turn both illuminators on (if you have a universal plinth fitted).  

    The difference illumination can make

    To the right are three images of a bank note taken from DISCOVERY with the universal plinth fitted.  The first is imaged with incident (top) illumination only.  The second is imaged with simultaneous incident (top) and transmitted (bottom) illumination.  The third image is imaged with transmitted (bottom) illumination only.  Note how the illumination selected changes the image and highlights the complexity of the bank note printing.