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PPDC Entomology lab

 

Dome lighting for insect imaging under a microscope

Build Instructions for a Dome Lighting System, using LED Flexible Strips

Please note that references to specific products below do not constitute endorsement. Equivalent dome systems may be made with similar types of materials, from a variety of sources.

If a relatively large staging area is needed and/or a DC power source is preferred, dome systems using LEDs mounted flush on prefabricated flexible strips is an adequate alternative. When selecting LED strips, be sure that the color temperature of the lights is no more than 5500K. There are a variety of sources for LED strips and the quality of the strips varies between manufacturers. In our experience, more expensive strips are better constructed, often with a protective, adhesive backing. The ones to the right (sourced here) are among the least expensive and are quite delicate but have served for our purposes.

Flexible strips each house 12-24 LED bulbs and range in price from $10-20 per strip. For a relatively large dome, such as one fashioned from a typical desk lamp, at least 48 LED bulbs will be needed to generate sufficient illumination.

Many standard desk lamp shades are suitable for our purposes. The most spherical ones, with an adequate ceiling for reflecting light, are ideal. The building process is simplified in cases where the shade attaches to the light fixture at its top (like the lamp to the right), since the oculus is already cut out.

 

The inner surface of the dome is painted with flat white enamel paint. Texture (e.g., orange peel) may also be sprayed onto the inside surface to enhance light dispersal.

To reduce the diameter of the oculus, cover discs may be used. Cover discs function as a kind of aperture, restricting the oculus to keep more light within the dome.

These cover disks are traced using a compass then cut out of card stock paper.

The LED strips are connected in series...
...then mounted directly to the base of a dome. For strips that lack backing, electrical tape is needed to protect the contact points from touching. Here, multiple strips are held together by black zip ties and tension against the dome keeps the LED strips in place.

Flexible LED strips require the additional task of connecting to a power supply and transformer (usually contained within the same unit, $10-20). This is easily done by soldering or crimping the wiring together and gives the flexibility of running the unit on either AC or DC power.

This system has additional connectors (in white) that allow for easy on/off switching, without handling the bulky plug.

A gray card serves as a suitable stage platform. A solid, flat platform is needed so that the entire system may be set up and moved under the scope as a single piece.

Although it simply looks like a piece of paper, the gray card to the right actually has a flat, hard cardboard backing. Its recommended that the card be affixed to a hard plastic board to protect against warping.

And gray modeling clay may be used for holding the specimen in place.
Components of the system.
In action.
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