Technically you can see interference pattern without a screen even though the source is not high intensity.
You don't need a screen to see interference pattern. The retina of you eyes can act as a screen Therefore, you don't need a strong light source. In fact, better not looking straight at a strong light source.
Light rays from a point source no matter how strong don't interference each other unless they are scattered (or diffracted or reflected) off by something else such as a window screen, bird's feathers, oil film etc that render interference pattern visible to us.