14 $$

    14 

    15 \begin{tikzpicture}[baseline,line width = 1pt,x=1.5cm,y=1.5cm]

    15 

    16 \draw (0,0) node(R) {}

    17 	-- (0.75,0) node[below] {$\bar{B}$}

    18 	--(1.5,0)  node[circle,fill=black,inner sep=2pt] {}

    19 	arc (0:80:1.5) node[above] {$D \times I$}

    20 	arc (80:180:1.5);

    21 \foreach \r in {0.3, 0.6, 0.9, 1.2} {

    22 	\draw[blue!50, line width = 0.5pt] (\r,0) arc (0:180:\r);

    23 }

    24 \draw[fill=white]

    25 	(R) node[circle,fill=black,inner sep=2pt] {}

    26 	arc (45:65:3) node[below] {$B$}

    27 	arc (65:90:3) node[below] {$A$}

    28 	arc (90:135:3) node[circle,fill=black,inner sep=2pt] {}

    29 	arc (-135:-90:3) node[below] {$C$}

    30 	arc (-90:-45:3);

    31 \draw[fill]  (150:1.5) circle (2pt) node[above=4pt] {$D$};

    32 \node at (-2,0) {\scalebox{2.0}{$\uparrow f$}};

    33 \node at (0.2,0.8) {\scalebox{2.0}{$\uparrow \psi$}};

    34 \end{tikzpicture}

    35 $$