var i = 0;
var j = 0;

var a_img_ps = new f_img_ps;
var a_img_bs = new f_img_bs;

function f_img_ps() {
  this[0]  = "media/slide/laser_ps_01.jpg";
  this[1]  = "media/slide/laser_ps_02.jpg";
  this[2]  = "media/slide/laser_ps_03.jpg";
  this[3]  = "media/slide/laser_ps_04.jpg";
  this[4]  = "media/slide/laser_ps_05.jpg";
  this[5]  = "media/slide/laser_ps_06.jpg";
  this[6]  = "media/slide/laser_ps_07.jpg";
  this[7]  = "media/slide/laser_ps_08.jpg";
  this[8]  = "media/slide/laser_ps_09.jpg";
  this[9]  = "media/slide/laser_ps_10.jpg";
  this[10] = "media/slide/laser_ps_11.jpg";
  this[11] = "media/slide/laser_ps_12.jpg";
  this[12] = "media/slide/laser_ps_13.jpg";
  this[13] = "media/slide/laser_ps_14.jpg";
  this[14] = "media/slide/laser_ps_15.jpg";
  this[15] = "media/slide/laser_ps_16.jpg";
  this[16] = "media/slide/laser_ps_17.jpg";
  this[17] = "media/slide/laser_ps_18.jpg";
  this[18] = "media/slide/laser_ps_19.jpg";
  this[19] = "media/slide/laser_ps_20.jpg";
  this[20] = "media/slide/laser_ps_21.jpg";
}

function f_img_bs() {
  this[0]  = "media/slide/laser_bs_01.jpg";
  this[1]  = "media/slide/laser_bs_02.jpg";
  this[2]  = "media/slide/laser_bs_03.jpg";
  this[3]  = "media/slide/laser_bs_04.jpg";
  this[4]  = "media/slide/laser_bs_05.jpg";
  this[5]  = "media/slide/laser_bs_06.jpg";
  this[6]  = "media/slide/laser_bs_07.jpg";
  this[7]  = "media/slide/laser_bs_08.jpg";
  this[8]  = "media/slide/laser_bs_09.jpg";
  this[9]  = "media/slide/laser_bs_10.jpg";
  this[10] = "media/slide/laser_bs_11.jpg";
  this[11] = "media/slide/laser_bs_12.jpg";
  this[12] = "media/slide/laser_bs_13.jpg";
  this[13] = "media/slide/laser_bs_14.jpg";
  this[14] = "media/slide/laser_bs_15.jpg";
  this[15] = "media/slide/laser_bs_16.jpg";
  this[16] = "media/slide/laser_bs_17.jpg";
  this[17] = "media/slide/laser_bs_18.jpg";
  this[18] = "media/slide/laser_bs_19.jpg";
  this[19] = "media/slide/laser_bs_20.jpg";
  this[20] = "media/slide/laser_bs_21.jpg";
  this[21] = "media/slide/laser_bs_22.jpg";
  this[22] = "media/slide/laser_bs_23.jpg";
  this[23] = "media/slide/laser_bs_24.jpg";
  this[24] = "media/slide/laser_bs_25.jpg";
  this[25] = "media/slide/laser_bs_26.jpg";
  this[26] = "media/slide/laser_bs_27.jpg";
  this[27] = "media/slide/laser_bs_28.jpg";
  this[28] = "media/slide/laser_bs_29.jpg";
  this[29] = "media/slide/laser_bs_30.jpg";
  this[30] = "media/slide/laser_bs_31.jpg";
  this[31] = "media/slide/laser_bs_32.jpg";
  this[32] = "media/slide/laser_bs_33.jpg";
  this[33] = "media/slide/laser_bs_34.jpg";
  this[34] = "media/slide/laser_bs_35.jpg";
  this[35] = "media/slide/laser_bs_36.jpg";
  this[36] = "media/slide/laser_bs_37.jpg";
  this[37] = "media/slide/laser_bs_38.jpg";
  this[38] = "media/slide/laser_bs_39.jpg";
  this[39] = "media/slide/laser_bs_40.jpg";
  this[40] = "media/slide/laser_bs_41.jpg";
  this[41] = "media/slide/laser_bs_42.jpg";
  this[42] = "media/slide/laser_bs_43.jpg";
  this[43] = "media/slide/laser_bs_44.jpg";
  this[44] = "media/slide/laser_bs_45.jpg";
  this[45] = "media/slide/laser_bs_46.jpg";
  this[46] = "media/slide/laser_bs_47.jpg";
  this[47] = "media/slide/laser_bs_48.jpg";
  this[48] = "media/slide/laser_bs_49.jpg";
  this[49] = "media/slide/laser_bs_50.jpg";
  this[50] = "media/slide/laser_bs_51.jpg";
  this[51] = "media/slide/laser_bs_52.jpg";
  this[52] = "media/slide/laser_bs_53.jpg";
  this[53] = "media/slide/laser_bs_54.jpg";
  this[54] = "media/slide/laser_bs_55.jpg";
  this[55] = "media/slide/laser_bs_56.jpg";
  this[56] = "media/slide/laser_bs_57.jpg";
  this[57] = "media/slide/laser_bs_58.jpg";
  this[58] = "media/slide/laser_bs_59.jpg";
  this[59] = "media/slide/laser_bs_60.jpg";
  this[60] = "media/slide/laser_bs_61.jpg";
  this[61] = "media/slide/laser_bs_62.jpg";
  this[62] = "media/slide/laser_bs_63.jpg";
  this[63] = "media/slide/laser_bs_64.jpg";
  this[64] = "media/slide/laser_bs_65.jpg";
  this[65] = "media/slide/laser_bs_66.jpg";
  this[66] = "media/slide/laser_bs_67.jpg";
  this[67] = "media/slide/laser_bs_68.jpg";
  this[68] = "media/slide/laser_bs_69.jpg";
}

function f_prev_ps() {
  if (i > 0) {i -= 1;} else {i = 20;}
  if (document.layers) {
    document.layers[1].document.images[2].src = a_img_ps[i];
  }
  else {
    document.getElementById("img_ps").src = a_img_ps[i];
  }
}

function f_next_ps() {
  if (i < 20) {i += 1;} else {i = 0;}
  if (document.layers) {
    document.layers[1].document.images[2].src = a_img_ps[i];
  }
  else {
    document.getElementById("img_ps").src = a_img_ps[i];
  }
}

function f_prev_bs() {
  if (j > 0) {j -= 1;} else {j = 68;}
  if (document.layers) {
    document.layers[1].document.images[3].src = a_img_bs[j];
  }
  else {
    document.getElementById("img_bs").src = a_img_bs[j];
  }
}

function f_next_bs() {
  if (j < 68) {j += 1;} else {j = 0;}
  if (document.layers) {
    document.layers[1].document.images[3].src = a_img_bs[j];
  }
  else {
    document.getElementById("img_bs").src = a_img_bs[j];
  }
}