What is an Optical Sensor?

Catalog

Optical sensors mainly include optical measuring instruments, encoders, optical fibers, gratings, and other devices. These devices cooperate with each other to enable the optical sensor to work normally and accurately measure various data. The design of the optical sensor is mainly to consider whether the detection target can appear. The target here is mainly whether various parameters can meet the requirements of the target, such as whether the values of various lengths can meet the requirements, so it is mainly used for various A variety of industrial, electronic products, and automated parts can meet the required targets.

I. Working Principle of Optical Sensor

Optical sensors and instruments are measured based on optical principles. It has many benefits, such as non-touch and non-destructive measurement, high-speed transmission, and telemetry, remote control, etc., including common optical measurement instruments, laser dry-and-type, grating, and coding. And optical sensors and instruments such as optical fiber type. In the plan, it is mainly used to check whether the policy object is present or to conduct various industrial, car, electronic goods, and retail initiatives.

The light-emitting diode illuminates the sampling surface, and the image to be sampled with severe illuminance is imaged on the CMOS through the lens. The CMOS converts the optical image into a matrix electrical signal and transmits it to the DSP. The DSP performs the image signal with the image stored in the previous sampling period. Compare and analyze, and then send a displacement interval signal to the interface circuit. The interface circuit communicates and processes the displacement signal sent by the DSP, calculates the displacement signal transmitted into the computer, and then further processes it through the driver program, and finally constitutes the displacement of the cursor in the system. Press your finger on one side of the glass plane, and an LED light source and a CCD camera are installed on the other side of the glass. The light beam emitted by the LED illuminates the glass at a certain angle. The camera is used to receive the light reflected from the glass surface. The ridgeline on the finger is in contact with the glass surface, and the valley line is not in contact with the glass surface. Therefore, the light shining on the glass surface of the fingerprint ridge line is diffusely reflected, while the light shining on the glass surface corresponding to the fingerprint valley line is totally reflected, so that in the image captured by the CCD camera, the part corresponding to the fingerprint ridge is darker, and the part corresponding to the fingerprint valley is lighter.

II. Types of Optical Sensor

There are many types of optical sensors, and various sensors have their own applications. Optical sensors mainly include optical image sensors, transmissive optical sensors, optical mouse sensors, and reflective optical sensors. The image sensor is mainly used for the overall measurement of the image, which can collect the rough image of the entire object on the sensing device so that people have an accurate understanding of the rough image of the object; the transmissive optical sensor can be used for projection and can be used for the internal device of the object. Sensing, collecting data for measurement and control; optical mouse sensor is a kind of measurement using people's touch control because the working principle of the mouse sensor is similar to the mouse, so it is named; the reflective optical sensor is mainly used for long-distance measurement. For example, to measure the distance between the earth and the moon, a reflective optical sensor must be used. Now let us study some representative optical sensors.

1. Avago ADNS-7550

This sensor is based on the company's LaserStream technology, which measures changes in position by optically acquiring sequential surface images (frames) and mathematically determining the direction and amplitude of movement. ADNS-7550 contains a sensor and a vertical cavity surface-emitting laser (VCSEL) in a single package. Compared with most oxide-based single-mode VCSELs, this type of VCSEL maintains single-mode operation over a wide output power range, consumes significantly less power than LEDs, and is used in optical navigation applications.

The solution includes an image acquisition system (IAS) that acquires microscopic surface images through a lens and lighting system. The image is processed by a digital signal processor (DSP), which calculates the relative displacement values of Δx and Δy. The microcontroller converts the data to a PS2, USB, or RF signal before sending it to the host PC or game console.

Avago's LaserStream technology is the world's first laser lighting system for high-performance navigation. When used in mouse applications, the mouse can track smoother surfaces more accurately than LED-based mice.

Features include wide operating voltage: 4.0 to 5.25V, small size, integrated molded lead frame chip package, high-speed motion detection up to 30ips and 8g, motion detection pin output, internal oscillator-no clock input required, 400- can be selected, 800, 1200, 1600, 2000-cpi resolution. Applications include laser mice, optical trackballs, and integrated molded lead frame input devices.

2. Avago ADNS-2700

AvagoADNS-2700 is a compact single-chip USB optical mouse sensor, specially designed for realizing a non-mechanical tracking engine in the computer mouse. The sensor is based on optical navigation technology, including an image acquisition system (IAS), digital signal processor (DSP), and USB stream output. In this sensor, IAS acquires microscopic surface images through the lens and illumination system provided by the adjustment lens. These images are processed by the DSP to determine the direction and distance of the movement. The DSP generates relative displacement values of Δx and Δy, which are converted into USB motion data. It is based on optical navigation technology, which uses optics to obtain continuous surface images (frames) and mathematically determine the direction and amplitude of movement to measure changes in position.

The sensor adopts 8-pin optical package and is designed for ADNS-5100-001 fine-tuning lens, ADNSLED component clip, and LED. Together, these components provide a complete and compact mouse sensor. There are no moving parts and precise optical alignment is not required, facilitating mass assembly.

The output format is USB. The device complies with the HIDRevision1.11 specification and is compatible with USBRevision2.0. The frame rate is changed inside the sensor to achieve tracking and speed performance without the use of many registers. The default resolution is specified as 1,000 counts per inch, and the maximum movement rate is 30 inches per second. A complete mouse can be constructed by adding a PC board, switches and Z-wheels, plastic casing, and cables. Applications include wired optical mice, trackballs, and integrated input devices.

3. ROHM BH1603FVC

BH1603FVC is used to obtain ambient light data and adjust the LCD and keyboard backlight of mobile phones to save power and improve visibility. Other applications include PDP TVs, notebook computers, portable game consoles, digital cameras, digital video cameras, PDAs, LCD monitors, and displays, and car navigation systems. Features include compact surface-mount package 3.0x1.6mm, spectral sensitivity is very close to the human eye, the output current is proportional to brightness, minimum power supply voltage is 2.4V, built-in shutdown function, 3-level controllable output current gain, 1.8V logic Input interface, low sensitivity change (±15%).

Adjusting the backlight intensity to compensate for changes in ambient light levels can save 50% or more of the total power required to operate selected electronic devices, thereby significantly improving talk time and expanding the device's feature set. In order to provide excellent performance, the backlight brightness must be controlled in a uniform manner under a wide range of ambient light conditions and light sources.

4. Sharp GP2Y0Di10Z0F 

GP2Y0Di10Z0F is composed of an integrated combination of photodiodes, infrared light-emitting diodes, and signal processing circuits. The triangulation provided by the three parts that make up the unit minimizes the influence of reflectivity, ambient temperature, and operating duration on distance detection. If the object exists within the specified distance range, the output voltage of the sensor will remain high, so that the sensor can also be used in proximity sensor applications.

Features of the RoHS-compliant sensor include digital output, a short detection distance of 100mm, a thin package size of 13.6x7x7.95mm, the current consumption of 5mA, a power supply voltage of 27 to 6.2V, and resistance to sunlight.

III. Applications of Optical Sensor

Optical sensors are mainly used in high-tech fields, especially in the aerospace industry. Optical sensors have an irreplaceable role. For example, during take-off or landing of an aircraft, or during a flight, optical sensors can be used to accurately grasp The height of the aircraft ensures the safe navigation of the aircraft; in national defense scientific research and the information industry, optical sensors also play a very important role. The use of optical sensing devices can greatly improve the accuracy of weapons and enhance national defense capabilities; It also plays an important role in medicine. The use of optical transmissive sensors can see through the inside of the human body and improve the effectiveness of medical treatment.

The types of optical sensors mainly include laser, infrared light, illuminance, visible light, and image sensors, etc., which use some inherent characteristics of light to develop rapidly sensing technologies. For example, the emergence of lasers has enabled radio technology and optical technology to advance, penetrate and complement each other by leaps and bounds. Nowadays, many sensors have been made by using lasers, which have solved many technical problems that could not be solved before, making them suitable for dangerous and flammable places such as coal mines, oil, and natural gas storage. There is also an optical fiber sensor made of laser, which can measure the parameters of crude oil injection and cracking of oil tanks. There is no need for a power supply at the actual measurement site, which is especially suitable for petrochemical equipment groups with strict requirements for safety and explosion-proof measures. It can also be used to implement optical telemetry chemical technology in some links of large steel plants.

The optical sensor mainly uses light as the medium to work, so its detection distance is very long. Through advanced design, the light can be concentrated into a beam of light on a small spot to achieve high resolution, and it can also pass through tiny objects. Detection and high-precision position detection. Optical sensors can also be used in the medical field. For some non-contact detections, optical sensors can detect internal conditions without touching the detected objects, without causing damage to the detected objects and sensors, which guarantees the human body’s Safety also enables the optical sensor to be used for a long time. The optical sensor can also be used for color discrimination. It distinguishes by monitoring the reflectance and absorptivity of the light formed by the object. This property is used to detect the color of the detected object.