The setup of laser interference is relatively simple, with 2/3/4-beam interferences being the common cases [
5,
17–
19]. Split beams from a coherent laser interfering on the sample are used to form a redistributed fringe-like intensity. The intensity period for the recorded structures is determined by laser wavelength
λ, refractive index
n, and the angle between the two beams,
θ. The laser wavelength is usually determined by photoresist linear absorption. Most laser sources are reported at 355 [
15], 325 [
11,
20], 266 [
5], 257 [
21], and 193 nm at deep ultraviolet wavelengths [
22], which limit the resolution of the structures with a minimum period of
λ/2
n. Thus far, the minimum period of 90 nm has been realized by the immersion method with a 45 nm half-pitch and two views of self-aligned frequency-doubled patterns at 22 nm half-pitch, followed by two potassium hydroxide (KOH) etch pattern-transfer steps [
22]. Ultra-short pulsed lasers, such as nanosecond and femtosecond lasers [
23], have also been used for laser interference. Considering the coherent length limitation, nanosecond laser sources are typically used in the fabrication of high-depth/width-ratio structures. The flexible tuning of beam angle widens the period from microscale to nanoscale and promotes its widespread applications in surface science [
5]. With the detailed multi-beam interference and multi-exposure of two-beam interference, structures such as microlenses [
10], photonic quasi-lattices [
24], and micro/nanopillars (micro/nanoholes) [
18,
25], and several micro/nanostructures based on these templates [
11,
16] are easily demonstrated.