%---------------------------------------------------------------------------
% SYNTAX:  f=r2f(R <,lenstype>)
%           <...> indicates optional arguments
%
%
% Uses a lookup table or a formula to obtain the focal length of a 
% spherical lens for 1064 nm light from the radius of curvature. 
%
%
%
% INTPUT ARGUMENTS:
% R        = radius of curvature [mm]
% lenstype = Defines the source to use for the conversion.  Can be on of
%            the following:
%
%           cvi_plcx_bk7   --  CVI corp. plano-convex, BK7 lenses
%           cvi_bicx_bk7   --  CVI corp. bi-convex, BK7 lenses
%           cvi_plcc_bk7   --  CVI corp. plano-concave, BK7 lenses
%           cvi_bicc_bk7   --  CVI corp. bi-concave, bK7 lenses
%           cvi_plcx_sio2  --  CVI corp. plano-convex, Fused Silica lenses
%           cvi_bicx_sio2  --  CVI corp. bi-convex, Fused Silica lenses
%           cvi_plcc_sio2  --  CVI corp. plano-concave, Fused Silica lenses
%           cvi_bicc_sio2  --  CVI corp. bi-concave, Fused Silica lenses
%           default        --  uses the formula R=2f.
%
% OUTPUT ARGUMENTS:
% f        = focal length of the lens [mm]
%
%---------------------------------------------------------------------------
% SYNTAX:  f=r2f(R <,lenstype>)
%-------------------------------------------------------------------------------

function f=r2f(R,varargin);

if nargin>=2, lenstype=varargin{1}; else lenstype='default'; end

switch lower(lenstype)
    case 'default'
        f=2*R;
    case 'cvi_plcx_bk7'
        rawdata=load('CVI_PLCX_bK7_r2f_index.txt');
        [data(:,1),sortorder]=sort(rawdata(:,1));   % R now in 1st col, in ascending order
        data(:,2)=rawdata(sortorder',2);            % f in 2nd column
        [posn,exactmatch]=pos(data(:,1),R);
        Rfound=data(posn,1);
        f=data(posn,2);
        if ~exactmatch
            disp(['R is not found in the catalog table.  Closest R is ',num2str(Rfound),' mm.']); 
        end
        disp(['R = ',num2str(Rfound),' -> R = ',num2str(f),' mm.']);
    case 'cvi_bicx_bk7'
        rawdata=load('CVI_BICX_BK7_r2f_index.txt');
        [data(:,1),sortorder]=sort(rawdata(:,1));   % R now in 1st col, in ascending order
        data(:,2)=rawdata(sortorder',2);            % f in 2nd column
        [posn,exactmatch]=pos(data(:,1),R);
        Rfound=data(posn,1);
        f=data(posn,2);
        if ~exactmatch
            disp(['R is not found in the catalog table.  Closest R is ',num2str(Rfound),' mm.']); 
        end        
        disp(['R = ',num2str(Rfound),' -> R = ',num2str(f),' mm.']);
    case 'cvi_plcc_bk7'
        rawdata=load('CVI_PLCC_bK7_r2f_index.txt');
        [data(:,1),sortorder]=sort(rawdata(:,1));   % R now in 1st col, in ascending order
        data(:,2)=rawdata(sortorder',2);            % f in 2nd column
        [posn,exactmatch]=pos(data(:,1),R);
        Rfound=data(posn,1);
        f=data(posn,2);
        if ~exactmatch
            disp(['R is not found in the catalog table.  Closest R is ',num2str(Rfound),' mm.']); 
        end
        disp(['R = ',num2str(Rfound),' -> R = ',num2str(f),' mm.']);
    case 'cvi_bicc_bk7'
        rawdata=load('CVI_BICC_BK7_r2f_index.txt');
        [data(:,1),sortorder]=sort(rawdata(:,1));   % R now in 1st col, in ascending order
        data(:,2)=rawdata(sortorder',2);            % f in 2nd column
        [posn,exactmatch]=pos(data(:,1),R);
        Rfound=data(posn,1);
        f=data(posn,2);
        if ~exactmatch
           disp(['R is not found in the catalog table.  Closest R is ',num2str(Rfound),' mm.']); 
        end          
        disp(['R = ',num2str(Rfound),' -> R = ',num2str(f),' mm.']);
    case 'cvi_plcx_sio2'
        rawdata=load('CVI_PLCX_SIO2_r2f_index.txt');
        [data(:,1),sortorder]=sort(rawdata(:,1));   % R now in 1st col, in ascending order
        data(:,2)=rawdata(sortorder',2);            % f in 2nd column
        [posn,exactmatch]=pos(data(:,1),R);
        Rfound=data(posn,1);
        f=data(posn,2);
        if ~exactmatch
            disp(['R is not found in the catalog table.  Closest R is ',num2str(Rfound),' mm.']); 
        end
        disp(['R = ',num2str(Rfound),' -> R = ',num2str(f),' mm.']);
    case 'cvi_bicx_sio2'
        rawdata=load('CVI_BICX_SIO2_r2f_index.txt');
        [data(:,1),sortorder]=sort(rawdata(:,1));   % R now in 1st col, in ascending order
        data(:,2)=rawdata(sortorder',2);            % f in 2nd column
        [posn,exactmatch]=pos(data(:,1),R);
        Rfound=data(posn,1);
        f=data(posn,2);
        if ~exactmatch
            disp(['R is not found in the catalog table.  Closest R is ',num2str(Rfound),' mm.']); 
        end        
        disp(['R = ',num2str(Rfound),' -> R = ',num2str(f),' mm.']);
    case 'cvi_plcc_sio2'
        rawdata=load('CVI_PLCC_SIO2_r2f_index.txt');
        [data(:,1),sortorder]=sort(rawdata(:,1));   % R now in 1st col, in ascending order
        data(:,2)=rawdata(sortorder',2);            % f in 2nd column
        [posn,exactmatch]=pos(data(:,1),R);
        Rfound=data(posn,1);
        f=data(posn,2);
        if ~exactmatch
            disp(['R is not found in the catalog table.  Closest R is ',num2str(Rfound),' mm.']); 
        end
        disp(['R = ',num2str(Rfound),' -> R = ',num2str(f),' mm.']);
    case 'cvi_bicc_sio2'
        rawdata=load('CVI_BICC_SIO2_r2f_index.txt');
        [data(:,1),sortorder]=sort(rawdata(:,1));   % R now in 1st col, in ascending order
        data(:,2)=rawdata(sortorder',2);            % f in 2nd column
        [posn,exactmatch]=pos(data(:,1),R);
        Rfound=data(posn,1);
        f=data(posn,2);
        if ~exactmatch
           disp(['R is not found in the catalog table.  Closest R is ',num2str(Rfound),' mm.']); 
        end          
    otherwise
        error('lenstype not recognized');
    end
end