This is a scan from page 121 of Van's autobiography Reflections of A.E. van Vogt. The picture itself was taken during a lengthy interview in 1961, the text of which forms the basis for the book (which was published thirteen years later).
The full uncropped photo which presumably no longer exists includes the interviewer, Elizabeth Dixon. The photographer, working for a magazine, wanted to take her picture alongside the interviewee she was to be the subject, with Van only an incidental inclusion. Ironically, Van's picture turned out so much better than hers as well as all other pictures taken of him that the prints were cropped to include only Van. Van's explanation for the success of this picture is that he was off-guard; it was intended that he would be cropped from the prints.
Van wrote that this is the only photo of himself that he likes, and that he looks nowhere near as good in real life. He picked it as the picture of himself he wished to preserve for posterity.