Views: 0 Author: Site Editor Publish Time: 2026-06-04 Origin: Site
An endoscope camera module is designed to see where your eyes cannot reach – inside a human joint, a jet engine, or a plumbing pipe. The lens at the tip of the scope is the most critical part. In ultra‑small spaces (diameters of 2–5 mm or even less), designing a lens that captures a sharp, wide, and well‑lit image is a serious optical challenge. This article explains how endoscope camera lenses work in such confined environments, and how different types of modules – from a mini camera module for medical use to a USB Camera Module for industrial borescopes – achieve this.
A typical camera lens for a smartphone is about 5‑8 mm in diameter. In an endoscope, the entire camera assembly must fit into a tube that is often smaller than a grain of rice. This means:
The lens must be extremely tiny – sometimes as small as 0.6 mm in diameter.
The number of lens elements is limited (often just one or two pieces of glass or plastic).
The lens must have a very short focal length to see objects that are only a few millimetres away.
The depth of field must be large so that objects from 3 mm to 50 mm appear sharp without autofocus.
The lens must be sealed against fluids and sterilisation (for medical use).
To achieve a wide field of view (typically 90° to 140°) and sufficient depth of field, endoscope lenses use one or a combination of the following techniques:
Aspherical surfaces – A single aspherical lens can replace two spherical lenses, saving space while correcting distortion and spherical aberration.
High‑index glass or plastic – Materials with a high refractive index bend light more, allowing a shorter focal length and a smaller lens.
Wafer‑level optics – Hundreds of tiny lenses are etched onto a glass wafer and then diced. This is used for disposable endoscopes.
Compound lens – Two or three tiny lens elements stacked together (e.g., a front negative lens and a rear positive lens) to improve image quality while keeping the diameter small.
The lens focuses light onto a cmos camera module sensor. In a typical endoscope camera module, the sensor is also very small – often 1/9″ to 1/6″ (about 1.5‑3 mm diagonal). The lens projects an image circle that matches the sensor’s active area. Because the lens is fixed‑focus, it is set to a hyperfocal distance. Everything from half that distance to infinity is acceptably sharp. For example, a lens set to 15 mm will keep objects from 8 mm to infinity in focus.
The sensor converts the light into electrical signals. In a modern cmos camera module, back‑illuminated (BSI) technology improves sensitivity, compensating for the small aperture.
Mini Camera Module (Medical or Industrial) – A mini camera module for a disposable endoscope (e.g., 2 mm diameter) uses a single plastic aspherical lens. The lens is glued directly onto the sensor using active alignment. The working distance is fixed, typically 5‑20 mm for medical use. There is no autofocus; the large depth of field covers the needed range.
USB Camera Module (Consumer Borescope) – A USB Camera Module for home inspection often has a 5.5 mm diameter tip with a three‑element glass lens. It may include a ring of white LEDs around the lens. The lens is fixed‑focus, set to a working distance of about 30‑100 mm. The image is streamed over USB 2.0, and the UVC camera module standard makes it plug‑and‑play.
OEM Camera Module (Custom Design) – For specialised applications, an OEM camera module can be designed with a custom lens. For example, a lens with a very wide field of view (140°) for pipeline inspection, or a macro lens for inspecting tiny electronics. The OEM supplier selects the lens material (glass for durability, plastic for cost), the number of elements, and the coating (anti‑reflective, hydrophobic).
UVC Camera Module – A UVC camera module is essentially a USB Camera Module that follows the USB Video Class standard. The lens characteristics are the same, but the firmware reports supported resolution and frame rates. The user does not need to install a driver.
In all but the cheapest endoscopes, the lens is not simply screwed into a holder. Instead, the manufacturer uses an active alignment process:
The sensor is powered on and displays a test chart.
The lens is moved in six axes (X, Y, Z, tilt, pitch, yaw) by a robotic manipulator.
Software analyses the image sharpness and centering.
Once the optimal position is found, the lens is fixed with UV‑curing adhesive.
Active alignment compensates for tiny mechanical tolerances in the lens holder and sensor placement. Without it, the image would be blurry on one side or the focus would be off. This process is critical for both a mini camera module for a 2 mm endoscope and a 4K industrial borescope.
In an ultra‑small space, there is no room for external lighting. Therefore, the endoscope camera module includes its own LEDs placed around the lens. The LEDs must be positioned so that:
They do not create a shadow from the lens barrel.
The light is directed forward (or sideward with a prism).
The illumination is uniform across the field of view.
The lens barrel itself may have a chamfered or recessed design to allow the LEDs to be placed closer to the optical axis, reducing dark spots.
Consider a disposable ureteroscope. The tip diameter is 2 mm. Inside, there is:
A single plastic aspherical lens, 1.4 mm in diameter.
A 1/9″ CMOS sensor (400×400 pixels).
Two white LED chips on the sides of the lens.
A flexible circuit that connects to the cable.
The lens has a focal length of 1.2 mm, giving a field of view of 90°. The working distance is 3‑15 mm. The image is soft at the edges (barrel distortion) but acceptable for seeing a kidney stone. The entire assembly is potted with epoxy for waterproofing and sterilisation.
Endoscope camera lenses for ultra‑small spaces rely on tiny aspherical optics, wafer‑level manufacturing, and active alignment to produce a sharp image. The lens works together with a cmos camera module sensor, and the whole assembly is often packaged into a mini camera module for medical or industrial use. For consumer applications, a USB Camera Module with UVC camera module compliance provides a plug‑and‑play solution with a fixed‑focus lens. For custom products, an OEM camera module allows full control over lens design, working distance, and sealing.
Understanding how these tiny lenses work helps you choose the right endoscope camera module for your application – whether you need to see inside a blood vessel, a turbine blade, or a household drain.
If you require a custom endoscope camera module – from a mini camera module to a high‑resolution USB Camera Module – contact Sincere. We design and manufacture OEM camera modules with precision optics and active alignment.
