Advantages and Disadvantages of Various Imaging Methods in Industrial borescopes

Industrial borescopes have diverse applications, but their imaging methods are a core technological differentiator. They can be mainly divided into three categories: optical straight-arm borescopes, fiber optic borescopes, and video borescopes. Each method has its unique working principle, advantages, disadvantages, and applicable scenarios.

The following is a detailed introduction:

1. Optical Straight-Arm borescope

This is the most traditional and basic imaging method, its core being multiple sets of optical lenses.

Working Principle: The objective lens group acquires images at the front end.

The image is transmitted within the endpiece through a series of precise image-transfer lenses.

The eyepiece group magnifies the image at the end, allowing direct observation by the human eye or connection to a camera.

Key Features:

High Image Quality: Due to pure optical transmission, the image is clear, with high color fidelity and no pixelation.

Robust Structure: The endpiece is rigid and not easily damaged.

Inflexible: Can only observe areas accessible by a straight line.

Requires an External Camera System: In modern applications, a CCD or CMOS camera adapter is usually connected to the eyepiece end to convert the optical image into an electronic signal for display on a screen. At this point, it essentially becomes a "rigid electronic borescope."

Typical applications: Fields requiring extremely high image quality, such as precision inspection of aircraft engines and turbine blades.

Inspection of straight pipes and holes.

2. Fiber Optic borescope

Uses fiber optic bundles to transmit images; the tubing is flexible.

Working principle: The core component is an image transmission bundle made of tens of thousands of extremely fine glass optical fibers. Each fiber transmits a single point of light.

The objective lens images the image onto the end face of the image transmission bundle, with each fiber independently transmitting the brightness of a single pixel.

All the fibers combine the light points at the other end to reconstruct the image, which is observed through the eyepiece or captured by a camera.

Another independent beam guide is responsible for transmitting illumination light from the main unit to the front end.

Key features: Flexible body: It can bend, bypass obstacles, and reach the interior of complex structures.

Grid-like image: Due to the arrangement of the fiber bundles, the image exhibits a unique "grid-like" or "mosaic" appearance, with lower clarity than optical and video borescopes.

Lower cost: Generally cheaper than video borescopes of the same diameter.

Core vulnerability: If the optical fiber in the image transmission bundle breaks, it will create a permanent black spot on the image.

Typical applications: Applications requiring flexibility but budget-sensitive or with extremely limited inspection space (diameter less than 1mm).

For example: Inspection of automotive engines, oil lines, and the internal cavities of castings.

3. Video borescope

This is currently the most technologically advanced and widely used imaging method, also known as an electronic borescope.

Working principle: A miniature image sensor (CCD or CMOS) is directly integrated at the very tip of the borescope.

This sensor directly converts the optical image at the tip into a digital electrical signal for output or storage.

The electrical signal is transmitted to the host computer via wires inside the borescope, and after processing, is directly output to the display screen.

Illumination is provided by LEDs at the tip or a light source transmitted through optical fibers.

Key features: Clear, grid-free images: Direct digital imaging, high image quality, and excellent color reproduction.

Feature-rich: Facilitates image storage, video recording, measurement (defect measurement), analysis, and report generation.

Intuitive operation: Direct screen viewing allows multiple viewers to watch simultaneously, reducing operator eye strain.

Thicker borescope body: Due to the integration of sensors and circuitry, it is typically thicker than fiber optic borescopes of the same diameter.

Higher cost: Complex technology and high manufacturing costs.

Divided into flexible and rigid types:

* Flexible video borescopes: The borescope body is flexible and has the widest range of applications.

* Rigid video borescopes: The borescope body is rigid, and the front end integrates sensors, combining the high-definition advantages of optical straight-bar borescopes with the digital advantages of video borescopes.

Typical applications: Industrial borescopes are used in almost all existing industrial sectors, such as petrochemicals, power, special equipment, railways, and shipbuilding.

Development trends: Currently, the technological development of industrial borescopes mainly focuses on video borescopes, moving towards higher resolution (e.g., 4K), smaller diameters, more intelligent defect identification (AI analysis), more accurate measurements, and stronger environmental adaptability (e.g., high-temperature resistance, explosion-proof). While optical straight lenses and fiber optic lenses still have irreplaceable value in specific fields, video borescopes are undoubtedly the mainstream and the future.