3.11.4 Experimental procedures
(1)Coaxial adjustment by course adjustment and fine adjustment methods mentioned above.
(2)Measurement of the focal length of the convex lens
①Flat mirror method:Arrange the optical path according to Figure 3.11.1 and adjust the coaxis.Determine and record the object position X1.Move the convex lens position,and adjust the plane mirror to make it perpendicular to the optical axis,so that the light is reflected back on the object plane.Then move the lens until a clear arrow image with the same size and opposite direction is obtained on the object screen.Record the position of the convex lens X2 and repeat the measurement for five times.
②Conjugate method:Arrange the optical path according to Figure 3.11.2 and adjust the coaxis.Determine and record the position of object and screen X1 and X2 respectively,and keep their distance A unchanged and make sure the condition d＞4f.Record the position of the lens for the large image X3 and small image X4.Repeat the experiment for five times.(https://www.daowen.com)
(3)Measurement of the focal length of the concave lens
①Plane mirror method:The object screen,convex lens and the image screen are placed on the light bench and then adjust the coaxis.Move the position of the screen to obtain a clear image,and record the position of the image X1.Insert a concave lens and a plane mirror(Figure 3.11.3)between the image plate and the convex lens,and adjust the concave lens to make the system coaxial.Move the concave lens until a clear arrow with the same size and opposite direction is observed on the object screen,and record the position of the concave lens X2.Repeat the experiment for five times.
②Object distance method:Replace the plane mirror in the experiment of plane mirror method with an image screen.Move the concave lens to ensure that the object distance of concave lens is less than its focal length.Record the position of concave lens X2(The X1 position is recorded is similar to the plane mirror method)and adjust the position of the image screen until a clearly enlarged image is obtained.Record the position of the image X3 and repeat the experiment for five times.
