How to get form data values in laravel controller

This is my ajax,

 $scope.update_defects = function(){
   
    var file_data = $('#fileaudio').prop('files')[0];
    var file_data1 = $('#filevideo').prop('files')[0];
    var form_data = new FormData();
   
    form_data.append('file', file_data);
    form_data.append('file1', file_data1);
    form_data.append('snag_id', $scope.projectSnagId);
    form_data.append('defect_id', $scope.defect_number);
    form_data.append('defect_type', $scope.defect_type);
    form_data.append('defect_desc', $scope.defect_desc);
                
    $http({
    url:"{{url('update_si_defects')}}",
    method:"POST",
    data:form_data,
    }).success(function(data,status,config,header){
  
    }).error(function(data,status,config,header){
    alert("Defect data retrival error");
    });
      
    }

This is my laravel controller,

public function update_si_defects(Request $request)
        {
        
        echo $request->defect_type;
        exit();       
        }

But i am unable to get the submitted values in controller, what is the correct way? please suggession any solution?