WPF 关闭程序 Aforge摄像头关闭不了 问题

public static Bitmap StaticBitmap = new Bitmap(100,100);

public void Cam_NewFrame(object sender, NewFrameEventArgs eventArgs)
    {

        lock (StaticHelper.StaticBitmap)
        {
            using (Bitmap b = (Bitmap)eventArgs.Frame)
            {
                StaticHelper.StaticBitmap = (Bitmap)b.Clone();
            }

        }

    }

private void timer1_Tick(object sender, EventArgs e)
    {
        lock (StaticHelper.StaticBitmap)
        {
            pictureBox1.Image = (Bitmap)StaticHelper.StaticBitmap.Clone();
        }
    }