F Series Optical Slit / Precision Pinhole

Description

Product Description

• A slit refers to a gap formed by a pair of baffles in the optical path, made of stainless steel; precision pinholes and slits are used to realize tiny point light sources in the optical path, laser beam filtering, etc.;
• Adjust the purity and intensity of incident monochromatic light, and also directly affect the resolution;
• Compatible with multiple series of Oeabt cage plates/mounts;

Optical slits are used in spectroscopic instruments, etc. Their main purpose is to realize optical experiments such as tiny star point light sources in the optical path and laser beam filtering through the combination of pinholes/slits with cage plate mounts, adjustment bases, lens sleeves and microscopic objectives. The pinhole can also be selected according to actual needs in terms of aperture size and outer diameter to meet different experimental purposes of users.

Technical Description

– Optical Slit

A slit refers to a gap formed by a pair of baffles in the optical path, used to adjust the purity and intensity of incident monochromatic light, and also directly affect the resolution.

Introduction and Characteristics of Slits:

Slits are mainly used in spectroscopic instruments, etc. According to the working principle of modern spectroscopic instruments, spectrometers can be divided into two categories: classical spectrometers and new-type spectrometers. Classical spectrometers are instruments based on the principle of spatial dispersion; new-type spectrometers are instruments based on the principle of modulation. All classical spectrometers are slit spectrometers, while modulation spectrometers are non-spatially dispersive and adopt circular hole light entry. According to the light-splitting principle of the dispersive component, spectroscopic instruments can be divided into: prism spectrometers, diffraction grating spectrometers, interference spectrometers, etc.

According to their functions, slits can be divided into entrance slits and exit slits. The entrance, exit and intermediate slits are important parts of the spectrometer. The main function of the entrance and exit slits is to control the instrument resolution, and the intermediate slit is mainly used to suppress stray light. For a spectrometer, even if a monochromatic light is used to irradiate the slit, the outgoing light always has a spectral distribution with a width of Δυ [also called frequency width]. This is mainly caused by factors such as the instrument grating, aberrations of the optical system, part processing and system adjustment, and thus determines the ultimate resolution of the instrument. In actual measurement, as the slit width increases, the resolution also decreases linearly, resulting in spectral line broadening.

The width of the exit slit is usually expressed in two ways: one is the actual width of the slit on the metal slit plate in millimeters, and the other is the spectral bandwidth, which refers to the spectral width of the light beam emitted by the exit slit, also in nanometers. For example, if the width of the exit slit is 6mm, it does not mean that the width of the exit slit is 6mm, but that the light emitted from this slit has a spectral bandwidth of 6nm. Pure monochromatic light is only an ideal situation. The “monochromatic light” obtainable by a spectrophotometer is actually a band with a certain wavelength range. The wider the slit, the wider the wavelength range it covers. For the purity of monochromatic light, the narrower the slit, the better, but the light intensity is also weaker. 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 minimum width achieved so far is 0.1nm. Corresponding slits should be selected for specific wavelengths, and slits also have an impact on resolution.

– Double-Slit Interference Experiment of Light

The setup of this experiment is very simple. Light emitted by a point light source is projected onto a background plate after passing through two slits. When the light passing through the slits reaches the background plate, what is projected is not two light bands, but many alternating bright and dark fringes.

The reason for these bright and dark fringes is that light is a wave. When light passes through two slits, it is equivalent to generating two new waves at the exits of the two slits. These two waves will interfere at different positions on the background plate. At the bright fringes, the wave crests of the two light waves coincide exactly when they arrive, and the intensity of the wave increases, so brighter fringes are produced. At the dark fringes, the wave crests and troughs of the two waves cancel each other exactly, and the intensity of the wave weakens, forming darker fringes.

– Precision Pinhole

Laser can be focused into a very small point, so it can be used as a nearly ideal point light source to generate spherical waves, which is very useful for optical systems. However, laser also has high coherence. Dust in the air, optical components or the laser itself often have some scattered light that can cause interference. Therefore, a small hole should be placed at the focused point to prevent stray light from passing through (for example, when focusing with a 10x microscope objective, the pinhole diameter is about 25μm). The role of this pinhole is similar to a filter in radio, which does not allow light of other spatial frequencies to pass through, so it is called pinhole filtering.

Multiple uses: ▶ Spatial filtering; ▶ Controlling beam diameter; ▶ Making point light sources; ▶ Image analysis;

To more accurately determine the position of photons passing through the slit, we can choose a narrower slit. However, from the law of diffraction, we know that the narrower the slit, the wider the central bright fringe on the screen. This indicates that although a narrower slit can measure the position of photons more accurately, the uncertainty of the photon momentum is greater.

☑ Product Description

(1) Optical slits are used in spectroscopic instruments, etc. Their main purpose is to realize optical experiments such as tiny star point light sources in the optical path and laser beam filtering through the combination of pinholes/slits with cage plate mounts, adjustment bases, lens sleeves and microscopic objectives. The pinhole can also be selected according to actual needs in terms of aperture size and outer diameter to meet different experimental purposes of users.

(2) These optical slits and optical pinholes are installed in Ø1 inch cage plate mounts, adjustment bases and lens sleeves, and are compatible with SM1 series products. Selecting the appropriate optical components and pinholes for your application needs to consider the incident wavelength, beam diameter and required output beam diameter.

Assembly

Application Examples

Engineering Drawing

F-1Engineering Drawing