Most state-of-the-art optical see-through head-mounted display (OST-HMD) lacks mutual occlusion capability between computer-rendered and real objects so that the virtual view through an OST-HMD appears "ghost-like", floating in the real world. In this paper, we demonstrated a light-weight, compact OST-HMD with mutual occlusion capability by exploring a highly innovative optical approach based on emerging freeform optical design and fabrication technologies. Our approach enabled us to achieve an occlusion-capable OST-HMD system with a very compelling form factor and high optical performance. The proposed display technology is designed for highly efficient liquid crystal on silicon (LCoS) type spatial light modulator (SLM) and bright Organic LED (OLED) microdisplay, which is capable of working in both indoor and outdoor environments. Our current design offered a 1280x1024 color resolution with a field of view (FOV) of 40 degrees and lightweight optics about 30 grams per eye.