Method for increasing speckle spot density, diffractive optical element, and projector

A diffractive optical element, which implements a function of increasing a speckle density of a projected speckle array by performing array replication on a multi-point light source and extension replication, wherein the diffractive optical element comprises:

• a beam-splitting point array, wherein the beam-splitting point array comprises:
• a first beam-splitting point array, which is used for performing array replication and projection on the multi-point light source to form a speckle array located in a first speckle region;
• a second beam-splitting point array, which is used for performing array replication and projection on the multi-point light source to form a speckle array located in a second speckle region;
• and
• a third beam-splitting point array, which is formed by performing extension replication, according to a minimum adjacent point spacing or an average adjacent point spacing of all or some of light-emitting points in the multi-point light source, on each beam-splitting point in the second beam-splitting point array, wherein a speckle array formed by performing array replication and projection on the multi-point light source through the third beam-splitting point array falls in the second speckle region to increase a speckle density in the second speckle region and keep a speckle density in the first speckle region unchanged.

A projector, comprising:

• a multi-point light source, which is used for generating a light beam;
• and
• a diffractive optical element, which is disposed downstream of an optical path of the multi-point light source and is spaced by a preset distance from the multi-point light source, and implements a function of increasing a speckle density of a projected speckle array by performing array replication on the multi-point light source and extension replication, wherein the diffractive optical element comprises:
• a beam-splitting point array, wherein the beam-splitting point array comprises:
• a first beam-splitting point array, which is used for performing array replication and projection on the multi-point light source to form a speckle array located in a first speckle region;
• a second beam-splitting point array, which is used for performing array replication and projection on the multi-point light source to form a speckle array located in a second speckle region;
• and
• a third beam-splitting point array, which is formed by performing extension replication, according to a minimum adjacent point spacing or an average adjacent point spacing of all or some of light-emitting points in the multi-point light source, on each beam-splitting point in the second beam-splitting point array, wherein a speckle array formed by performing array replication and projection on the multi-point light source through the third beam-splitting point array falls in the second speckle region to increase a speckle density in the second speckle region and keep a speckle density in the first speckle region unchanged.