如何在PHP中将Pdf文件转换为字节数组并发送？

I have found pdf to byte array and vice-versa in java,dotnet and python. But i want to convert pdf to byte array in php laravel. I am using "IMUIS" which is accounting software solution and need to sending journal entries from laravel lumen to "IMUIS" for processing.But it gives the error after converting.I have found pdf to byte array and vice-versa i