This setup, known as a conoscope, is shown in Figure 14. 2 and consists of two stress-free plane-convex lenses A and B and a diaphragm C having a small aperture.

• 此装置称为锥光镜；如图14.；2所示；它由A和B两个无应力平凸透镜和一个带小孔的光阑C组成。