Use Of Bertrand Lens - Optika Italy B-380 Serie Manual De Instrucciones

10.4 Use of Bertrand lens

• Bertrand lens allows observation in Orthoscopy
and Conoscopy.
• In the disengaged position ("O") the lens allows
observation in Orthoscopy, while in the inserted
position ("B") it is possible to make observations
in Conoscopy.
1. Rotate the upper knurled ring of the Bertrand lens
① to engage the "B" position. (Fig. 20)
2. Using one objective from 20x to 60x, focus the
conoscopic image using the focus ring ②.
3. If the conoscopic image is not perfectly centred
with respect to the optical axis, centre the image
using the centering screws ③.
• By turning the stage you will see black fringes
that will appear and disappear depending on
the rotation of the stage. These fringes are the
crystallization axes of that specific crystal. (Fig.
21)
①
Page 15
③
F ig. 20 F ig. 20
②
F ig. 21 F ig. 21