An imaging instrument has been developed by Microelectronic Systems for applications in automated handling and processing of filter paper samples in a medical laboratory.  The instrument (pictured) records the image formed by passing high intensity LED light through a flat paper medium.  Typically the paper would contain samples of dried blood in the form of circular patterns.

A linear array detector and associated optics are housed within a moveable head which is position controlled using a motor.  A strip of LED light is emitted from the lower portion of the head.  By moving the heads across the paper medium and by synchronised scanning and recording, an image of the light transmission and hence optical density of the material is recorded.

This is an example of an image recorded by the instrument during the test phase.  It shows a filter paper card with 5 circles that indicate where the blood spots are normally placed.  The cross-hatches and numerals were placed using a lead pencil.  Variations in the optical density of the paper can be clearly seen.  The dark area at the boundary of the card is a cardboard frame.

Generating the card image is only part of the functionality of the instrument.  The ultimate goal is to process the image to determine the positions on the card where suitable blood samples can be punched.  The image shown here is a false colour mapping to show where the instrument has found suitable blood density.  The white circle in the middle of the spot is a previous punch.  The other white areas are where the blood is too thin or absent.  Grey areas are the suggested punch sites arranged by the instrument to take as many punches of a given diameter as possible.  Up to two different punch sizes can be simultaneously used - algorithms find the best punch pattern for a mix of two different punch sizes for each blood spot.  A 150MHz DSP chip is used to scan and process the image in a few seconds to ensure fast throughput of samples.