Notes on the macroscopy of insect mounts using
near infrared illumination.

by Dave Walker (UK)

 

Honey bee, brightfield, part of head exoskeleton showing the three ocelli (the simple eyes), seen as an inverted triangle of circular holes. This section required high illumination levels in brightfield to record this image as evidenced by the burnt out edge definition.

The same subject in near IR. The layout of the hairs and other detail is easier to see now and photograph.

 

 

Insect head, brightfield. This is fairly transparent in brightfield and showed a lot of contrasty detail. Although the camera still struggled with this dynamic range as mouthparts detail was lost.

Insect head, near IR. A flatter less pleasing image but both visible and near IR images are useful as they can each reveal different aspects of the surface and internal structure.

The bee ocelli and diving beetle slides were prepared by the author but with the expert help of the now sadly missed Eric Marson of Northern Biological Supplies (UK) at one of his excellent Belstead House, Suffolk courses on slide-making.

Cautionary footnote If using a TV or monitor, especially with phono inputs where the signal connection can be made before the earth, it's best to make all video connections while the TV and camera are off, not even with TV in 'standby'. Apparently there can be floating voltage differences between camera and TV/monitor high enough to damage video camera circuitry, as the author has found out to his cost! Thank you to my brother Ian for this insight.

References and Further reading
1) 'Constructing and adapting sub-miniature CCD TV cameras to the microscope' by J A Dutton. Bulletin of the Quekett Microscopical Club, 1997, 30, p. 21-22. Also the record of a demonstration by J A Dutton at the QMC Annual Exhibition (1997) on p.41-42 of the same issue which reported the suitability of transmitted near infrared for imaging insects and other subjects.

A colleague has kindly informed me that two articles have been published below which the author hasn't seen to date.

2) 'Infrared Light in the Microscope: History, Theory & Practical Aspects' by Tim Richardson. Proceedings of the Royal Microscopical Society, Vol 32, Part 4 December 1997, pp. 229-235.

3) 'Practical Infrared' by Tim Richardson. Proceedings of the Royal Microscopical Society, Vol 32, Part 4 December 1997, pp. 236-242. 

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