

As the core component of 3D vision technology, TOF (Time of Flight) lenses have become indispensable in security, industrial, consumer electronics, and other sectors due to their real-time depth measurement capabilities. However, the performance of TOF lenses depends not only on optical design but also on assembly precision—active alignment technology is the key to unlocking their maximum potential. This article systematically explains the principles, advantages, and differences between active and passive alignment for TOF lenses, and delves into the technical adaptability and application scenarios of three popular Towin TOF lens models, providing practical references for industry selection.
Active alignment technology for TOF lenses is a closed-loop assembly solution with the following core logic:
In simple terms, active alignment is a precise assembly method of “testing while assembling and adjusting while testing,” with the core goal of eliminating optical deviations caused by mechanical tolerances and ensuring the depth measurement accuracy and field-of-view consistency of TOF lenses.
TOF systems operate based on 3D depth-sensing principles, imposing unique alignment requirements. The specific technical challenges, their impacts, and the active alignment solutions are summarized below:
| Technical Challenge | Impact | Active Alignment Solution |
| Optical axis deviation | Depth measurement errors, point cloud distortion | Achieve precise coincidence of lens and sensor optical axes via 6DoF adjustments |
| Sensor tilt relative to the image plane | Parallax errors, uneven depth measurement accuracy | Dynamically correct tilt angles (pitch/yaw) to ensure image plane flatness |
| Chief Ray Angle (CRA) mismatch | Pixel crosstalk, reduced signal-to-noise ratio (SNR) | Optimize lens position to match the technical parameters of the microlens array |
| Transmitter/receiver optical path misalignment | Signal attenuation, limited detection range | Achieve high-precision alignment of the Vertical-Cavity Surface-Emitting Laser (VCSEL) and receiver sensor optical paths |
| Fluctuations in manufacturing tolerances | Inconsistent performance across products | Compensate for manufacturing deviations in lens elements, holders, and sensors |
The optical structure and functional characteristics of TOF lenses dictate specific assembly requirements, for which active alignment is the core solution:
Technical Comparison: Active vs. Passive Alignment for TOF Lenses
| Comparison Dimension | Active Alignment Technology | Passive Alignment Technology |
| Alignment Principle | Dynamic adjustment based on real-time depth data feedback | Static positioning based on mechanical fixture tolerances |
| Assembly Precision | Micron-level (within ±1μm) | Hundred-micron level (around ±50μm) |
| Performance Consistency | High (batch deviation < 3%) | Low (batch deviation > 10%) |
| Distortion Control Effect | Real-time correction, qualification rate > 99% | Dependent on optical design, qualification rate < 85% |
| Adapted Products | High-resolution, wide-angle, low-distortion TOF lenses | Entry-level, low-precision TOF lenses |
| Mass Production Efficiency | Medium (10-20 seconds per unit) | High (3-5 seconds per unit) |
| Comprehensive Cost | Higher (requires testing equipment + algorithms) | Lower (only mechanical fixtures needed) |
| Application Scenarios | Security, industrial, 3D scanning | Toys, entry-level sensing devices |
All three Towin TOF lens models (S08012004812IR, S04112009316IR, S01714012013IRB9) feature hardware compatible with active alignment technology. Below is a parameter comparison and technical analysis:
| Parameter Dimension | S08012004812IR | S04112009316IR | S01714012013IRB9 |
| Model | S08012004812IR | S04112009316IR | S01714012013IRB9 |
| Effective Focal Length (E.F.L.) | 8.0mm | 4.1mm | 1.7mm |
| Diagonal Field of View (D.F.O.V.) | 60° | 120° | 147° |
| Horizontal Field of View (H.F.O.V.) | 48° | 93° | 120° |
| Resolution | 640×480 | 320×480 (nominal) | 640×480 (5.6μm) |
| Aperture (FNo.) | F1.2 | F1.6 | F1.3 |
| Maximum Distortion Rate | < -10% | < -41% (optical) / -13% (TV) | < -59% |
| Sensor Size | 1/2″ | 1/2″ | 1/4″ |
| IR Filter | 940nm BPF | – | 940nm Bandpass Filter |
| Mount Interface | M12×0.5 | M12×0.5 | M12×0.5 |
| Optical Structure | – | 6G+1ASPG | – |
| Total Length (T.T.L.) | 23.7mm | 23.50mm | 14.84mm |
| Core Features | Low distortion, security-specific | Wide angle, uniform image quality | Ultra-wide angle, 3D scanning-specific |
S08012004812IR: Low-Distortion Security-Specific TOF Lens
S04112009316IR: Wide-Angle Universal TOF Lens
S01714012013IRB9: Ultra-Wide Angle TOF Lens for 3D Scanning

Low-distortion M12 TOF lens
Q1: Will active alignment technology increase the cost of TOF lenses?
A1: It will slightly increase hardware (testing equipment) and time costs, but can boost product yield to over 95%, reducing long-term comprehensive costs—ideal for mid-to-high-end scenarios.
Q2: Which Towin lens is suitable for indoor low-light security?
A2: The S08012004812IR is preferred, with its F1.2 large aperture and 940nm IR filter delivering clear depth sensing in low-light environments and low distortion preventing image deformation.
Q3: Can active alignment improve TOF lens distortion?
A3: Yes. Active alignment corrects “additional distortion” caused by assembly, ensuring the distortion rate stays within the nominal range when combined with the lens’s inherent optical design.
Q4: What are the advantages of the M12 interface?
A4: The M12×0.5 is an industry-standard interface with strong compatibility, directly adapting to mainstream TOF sensor modules and simplifying device integration and post-maintenance.
Q5: Why do ultra-wide angle TOF lenses rely more on active alignment?
A5: Edge light in ultra-wide angle lenses is susceptible to assembly deviations, leading to field-of-view shifts and excessive distortion. Active alignment dynamically compensates for these deviations to ensure consistent precision across the entire field of view.
The depth sensing performance of TOF lenses is the “dual result” of optical design and assembly precision, with active alignment technology being the key to breaking through assembly precision bottlenecks. Through real-time data feedback and dynamic calibration, active alignment not only addresses the low-distortion, wide-angle, and high-precision requirements of TOF lenses but also ensures batch production consistency.
Towin’s three TOF lens models cover low-distortion, wide-angle, and ultra-wide angle scenarios. Their hardware parameters (large aperture, IR filter, standard interface) are highly compatible with active alignment technology, providing cost-effective solutions for security, industrial, smart home, and 3D scanning applications.
As 3D vision technology becomes more widespread, TOF lens application scenarios will continue to expand, and active alignment technology will evolve toward “higher precision and efficiency.” Choosing TOF lenses compatible with active alignment technology is a critical decision to ensure product performance and enhance market competitiveness.