Slit sheet is a kind of fine accessories applied to spectroscopic instruments, which are divided into two categories: classical spectrometers and new spectrometers. The former is an instrument built on the principle of spatial dispersion, and the later is an instrument built on the principle of modulation. The slit slice is the gap formed on the optical path by a pair of spacers, which regulates the purity and intensity of the incident monochromatic light, and also directly affects the resolution.。

The actual width of the slit on the slit sheet is expressed in millimeters, while the spectral band width, i.e., the spectral width of the outgoing slit, is likewise expressed in millimeters. When the width of the outgoing slit is 6 mm, the slit referred to emits light 6 mm spectral bandwidth. Pure monochromatic spectrophotometer can get the monochromatic light actually has a certain wavelength range of the spectral band. The wider the slit, the wider the wavelength range. For the purity of monochromatic light, the narrower the slit, the better, but the weaker the intensity of light. Therefore, the slit cannot be infinitely small. The minimum width of the slit depends on the minimum light energy that the detector can accurately measure. The production process of slit sheets is divided into photochemical etching and laser cutting. However, common precision instruments are usually produced by photochemical etching of the entire version, and the minimum slit width of the narrow slit sheet can be achieved at 0.05mm. After etching, the slit sheet is blackened throughout the version, and then removed in bulk for packaging and shipping。

 Laser cutting slit width can also reach 0.05mm, but the cutting slit will have laser sintering residue, the slit is not fine enough, the precision requirements of low optical instruments.Slit sheet etching processCompared to the laser cutting process，i.e.Slit sheet etching processIn the pursuit of high precision and micron-level tolerances by etching process can achieve the ideal state.