Provided is a holographic data storage system characterized by including: a first polarizing beam splitter (PBS), wherein at least either of a first lens module and a second lens module transmits P-polarized light and reflects S-polarized light; a relay lens collecting light passing through the first PBS; a mirror reflecting the light collected through the relay lens back to the relay lens; and a quarter wave plate located between a second PBS beam splitter and the relay lens, converting transmitted linearly polarized light into circularly polarized light, and converting the circularly polarized light into linearly polarized light. By reducing the volume of the relay lens, it is possible to decrease the size of the holographic data storage system, and by decreasing the number of lenses, it is possible to lower manufacturing costs.

Provided is a holographic data storage system characterized by including: a first polarizing beam splitter (PBS), wherein at least either of a first lens module and a second lens module transmits P-polarized light and reflects S-polarized light; a relay lens collecting light passing through the first PBS; a mirror reflecting the light collected through the relay lens back to the relay lens; and a quarter wave plate located between a second PBS beam splitter and the relay lens, converting transmitted linearly polarized light into circularly polarized light, and converting the circularly polarized light into linearly polarized light. By reducing the volume of the relay lens, it is possible to decrease the size of the holographic data storage system, and by decreasing the number of lenses, it is possible to lower manufacturing costs.

In a case where (i) a reflectance calculated from a reflected light amount obtained from a longest pit (P1max) or a longest space (S1max) in a first pit row is defined as a first reflectance and (ii) a reflectance calculated from a reflected light amount obtained from a longest pit (P2max) or a longest space (S2max) in the second pit row is defined as a second reflectance, the first pit row is formed such that the first reflectance becomes substantially identical with the second reflectance.

In a case where (i) a reflectance calculated from a reflected light amount obtained from a longest pit (P1max) or a longest space (S1max) in a first pit row is defined as a first reflectance and (ii) a reflectance calculated from a reflected light amount obtained from a longest pit (P2max) or a longest space (S2max) in the second pit row is defined as a second reflectance, the first pit row is formed such that the first reflectance becomes substantially identical with the second reflectance.