[Tex/LaTex] Align Caption to the left

captionshorizontal alignment

enter image description here

I am trying to align caption to the left but its coming centered. Please see the figure. The code is 

\begin{figure}[!t]
\includegraphics[scale=0.22]{Figure 1.pdf}
\caption{The caption is coming to the center. It should be aligned to the left. }
\label{Figure 1}
\end{figure}

The previously mentioned solutions were tried. But they didn't work.
How can I left-align a caption?

Any solution for the above problem.

A full MWE:

\documentclass[%
 aip,
 amsmath,amssymb,
]{revtex4-1}
\draft

\usepackage{graphicx}
\usepackage{dcolumn}
\usepackage{bm}
\usepackage{times}
\DeclareGraphicsExtensions{.pdf,.jpeg,.jpg, .png, .eps, .tiff}
\usepackage{epstopdf}
\usepackage{lipsum}
\usepackage{tabularx}
\usepackage{booktabs}
\usepackage{array}
\usepackage{natbib}
\usepackage{color}
\usepackage{grffile}
\usepackage{caption}
\usepackage{boxhandler}
\usepackage{float}
\begin{document}

\begin{figure}[!t]
\centering
\includegraphics[scale=0.5]{Figure 3.pdf}
\caption{}   
\label{Figure 4}
\end{figure}
\end{document}

Best Answer

You should add the following instruction to the preamble, after loading the caption package:

\captionsetup{justification=raggedright,singlelinecheck=false}

If you want "hanging indentation" of multiline captions, you should add the option

format=hang

to the argument of \captionsetup.

A full MWE (with all packages not relevant for the issue at hand removed from the preamble):

enter image description here

\documentclass[aip,amsmath,amssymb,draft]{revtex4-1}
%%% \draft % this instruction is deprecated -- use 'draft' option instead

\usepackage[demo]{graphicx} % remove 'demo' option in real document
\usepackage{times}
\usepackage{caption}
\captionsetup{justification   = raggedright,
              singlelinecheck = false}
\begin{document}
\setcounter{figure}{2}  % just for this example

\begin{figure}[!t]
\includegraphics[width=\textwidth]{Figure3.pdf}
\caption{The caption is now no longer centered. Instead, it is left-aligned, which is also known as ``ragged-right''.}   
\label{fig:3}
\end{figure}

\end{document}
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