Leica DM1000 LED manual Rotate the lambda plate compensator out of light path fig, Procedure

10. Measurements with the Microscope

10.3 Differentiation of Gout / Pseudo Gout

The use of the lambda plate compensator* is a prerequisite for this test.

Assembly → p. 24.

Orienting the Lambda Plate Compensator

•Rotate the lambda plate compensator out of light path (fig. 51)

•Bring the lambda plate compensator and analyzer into cross position until they reach maximum darkness (polarization → p. 45)

•Fix the cross position thus determined with the clamping screw at the side (51.2)

•Swing in the lambda plate again

Fig. 51 Lambda plate compensator swung out

1Orientation handle

2Clamping screw

2

90° 1

The following section explains the basic procedure for gout/pseudo gout differentiation. This test is made possible due to the negative birefringence of urates and positive birefringence of pyrophosphates. Both gout (monosodium urate) and pseudo gout (calcium pyrophosphate) crystals tend to be needle shaped. However, many crystals may be broken and/or irregular. To do the test, it is necessary to find at least one intact crystal orientated on same axis as orientation handle and one per-pendicular to axis.

Procedure

To insure the test is being done correctly, a slide of known monosodium urate crystals should be used initially.

•Use of a 40x objective is recommended

•Swing the lambda plate out of the path of light (fig. 51)

•Place the slide on the stage and bring crystals into a sharp focus; the needle shaped crystals will appear white regardless of orientation

•Swing in the lambda plate and put the orientation handle (51.1) into it’s extreme left position; crystals with a long dimension in the handle direction should appear yellow and the perpendicular to handle direction blue (fig. 52)

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