To form the image on the object itself, the object should kept at centre of curvature of a concave mirror.
1) An object AB has been placed at the centre of curvature 'C' on the concave mirror.
2) A ray of light AD which is parallel to principle axis passes through the focus 'F after reflection as DA'.
3) A ray of light passing through the focus of the concave mirror becomes parallel to the principle axis after reflection.
4) Here AE ray passing through focus and reflected as EA'.
5) The reflected rays DA' and EA’ meet at A' point. So the real image formed at point A of the object.
6) To get couple image A'B' perpendicular to the principle axis.
7) Thus A'B' is the real image of the object AB.