function thickness(form) { A=Math.round(eval(form.A.value)); Dbl=Math.round(eval(form.Dbl.value)); PD=Math.round(eval(form.PD.value)*10)/10; Sph=eval(form.Sph.value); Cyl=eval(form.Cyl.value); Axis=Math.round(eval(form.Axis.value)); //validation of form fields if (A<30 || A>80) {alert('The A size must be between 30mm and 80mm'); document.getElementById('A').focus();return false;} if (Dbl<10 || Dbl>25) {alert('The Dbl size must be between 10mm and 25mm'); document.getElementById('Dbl').focus();return false;} if (PD<40 || PD>75) {alert('The patients PD must be between 40mm and 75mm'); document.getElementById('PD').focus();return false;} if (Sph<-20 || Sph>15) {alert('The spherical power cannot exceed +15.00D or -20.00D'); document.getElementById('Sph').focus();return false;} if (Cyl<-8 || Cyl>8) {alert('The cylinder power cannot exceed 8.00D'); document.getElementById('Cyl').focus();return false;} if (A<1 || A>180) {alert('The axis must be between 1 and 180 degrees'); document.getElementById('Axis').focus();return false;} //helper functions function toRad(deg) { angle=deg*(Math.PI/180); return angle; } function toDeg(rad) { angle=rad*(180/Math.PI); return angle; } //Transpose the Rx to minus cylinder if (Cyl>0) { Sph=Sph+Cyl; Cyl=(-1)*Cyl; if (Axis>90) {Axis=Axis-90;} else {Axis=Axis+90;} } document.getElementById('Sph').value=Sph.toFixed(2); document.getElementById('Cyl').value=Cyl.toFixed(2); document.getElementById('Axis').value=Axis; //Lens array with index and minimum thickness var Lens = new Array(); Lens[0]=new Array('CR-39','1.498','2.0'); Lens[1]=new Array('Triv','1.527','1.0'); Lens[2]=new Array('Poly','1.586','1.0'); Lens[3]=new Array('Hi-1.60','1.592','1.5'); Lens[4]=new Array('Hi-1.67','1.661','1.5'); Lens[5]=new Array('Su-1.70','1.700','1.5'); Lens[6]=new Array('Su-1.74','1.732','1.5'); //Step 1 - determine minimum blank size MBS=Math.abs((A+Dbl)-PD)+A; MBS=Math.round(MBS); //Step 2 - determine power along the 180 Power=Sph+Cyl*Math.pow(Math.sin(toRad(Axis)),2); Power=Math.round(Power*100)/100; //Start looping through materials var Thick=new Array(); var AsphThick=new Array(); var counter=0; while (counter<=6) { //Step 3 - determine the back curve of the lens using 3rd order theory for a point focal lens design Index=eval(Lens[counter][1]); minthick=eval(Lens[counter][2]); ap=Index+2; bp=2*37*(Math.pow(Index,2)-1)-Power*(Index+2); cp=-2*Power*37*(Index-1)+Index*Math.pow(Power,2)+Index*Math.pow(37,2)*Math.pow(Index-1,2); discrim=Math.pow(bp,2)-4*ap*cp; if (discrim>=0) {Back=(-bp+Math.sqrt(discrim))/(2*ap);} else {Back=(Power/2)-((37*(Math.pow(Index,2)-1))/(Index+2));} //Step 4 - determine the average thickness averagethick=(Math.abs(Power)*Math.pow((MBS/2),2))/(2000*(Index-1))+minthick; averagethick=Math.round(averagethick*100)/100; //Step 5 - determine the front curve of the lens Front=Math.round(Power-Back); //Step 6 - determine the real back curve of the lens difference=1; while (Math.abs(difference)>0.1) { Back2=Power-Front/(1-averagethick*Front/(Index*1000)); RadFront=((Index-1)/Front)*1000; RadBack=Math.abs(((Index-1)/Back2)*1000); sagFront=RadFront-Math.sqrt(Math.pow(RadFront,2)-Math.pow((MBS/2),2)); sagBack=RadBack-Math.sqrt(Math.pow(RadBack,2)-Math.pow((MBS/2),2)); if (Power>0) {thickness=sagFront+minthick-sagBack;} if (Power<0) {thickness=sagBack+minthick-sagFront;} if (Power==0) {thickness=minthick;} difference=averagethick-thickness; averagethick=thickness+(difference/2); } thickness=averagethick; //Step 7 - factor in aspheric curvature //if (Aspheric==1) { //if (Power>0) {thickness=thickness*0.75}; //if (Power<0) {thickness=thickness*0.8}; //} //Step 8 - display the data Thick[counter]=Math.round(thickness*10)/10; if (Power>0) {AsphThick[counter]=Math.round(thickness*0.75*10)/10;} if (Power<0) {AsphThick[counter]=Math.round(thickness*0.80*10)/10;} if (Power==0) {AsphThick[counter]=Math.round(thickness*10)/10;} counter++; } //write to the screen all the thicknesses and data document.writeln(''); if (Power>=0) { document.writeln(''); document.writeln('For a: \+' + Sph.toFixed(2) + ' \-' + Cyl.toFixed(2) + ' ' + ' x ' + Axis + ' Lens
'); document.writeln('with a minimum blank size of: ' + MBS + 'mm

'); document.writeln(''); counter=0; while (counter<=6) { if (isNaN(Thick[counter])) {displayThick='Len';displayAsphThick='Len';} else {displayThick=Thick[counter].toFixed(1)+'mm';displayAsphThick=AsphThick[counter].toFixed(1)+'mm';} document.writeln(''); counter++; } } if (Power<0) { document.writeln(''); document.writeln('For a: ' + Sph.toFixed(2) + ' \-' + Cyl.toFixed(2) + ' ' + ' x ' + Axis + ' Lens
'); document.writeln('with a minimum blank size of: ' + MBS + 'mm

'); document.writeln('
MaterialIndexEdge (min)CenterAsph
'+ Lens[counter][0] +''+ Lens[counter][1] +''+ Lens[counter][2] +'mm' + displayThick + '' + displayAsphThick + '
'); counter=0; while (counter<=6) { if (isNaN(Thick[counter])) {displayThick='Len';displayAsphThick='Len';} else {displayThick=Thick[counter].toFixed(1)+'mm';displayAsphThick=AsphThick[counter].toFixed(1)+'mm';} document.writeln(''); counter++; } } document.writeln('
MaterialIndexEdgeAsphCenter (min)
'+ Lens[counter][0] +''+ Lens[counter][1] +''+ displayThick +'' + displayAsphThick + '' + Lens[counter][2] + 'mm


'); document.writeln(''); document.writeln('
Luzerne Optical Laboratories'); document.writeln('
(800)233-9637'); document.writeln(''); return; } //Repopulate with default value function replaceDefault(el) {if (el.value=="") el.value=eval(el.defaultValue);} //Clear default values from input boxes function clearDefault(el) {if (el.defaultValue==el.value) el.value = "";} //Transpose function transpose() { Sph=eval(document.getElementById('Sph').value); Cyl=eval(document.getElementById('Cyl').value); Axis=eval(document.getElementById('Axis').value); if (Cyl>0) {Sph=Sph+Cyl; Cyl=(-1)*Cyl; if (Axis>90) {Axis=Axis-90;} else {Axis=Axis+90;} } document.getElementById('Sph').value=Sph.toFixed(2); document.getElementById('Cyl').value=Cyl.toFixed(2); document.getElementById('Axis').value=Math.round(Axis); } //Redirect to pages in app function redir(r) {location.replace(r);}