With that said, the 3-pack of “Meusno” brand AAA-powered laser pointers that TTC tested is on sale for $10 right now. Reviewers confirm they are bright, but poor quality and likely to break. I was about to place an Amazon order anyways, so for a little over $3 each, I think I will give them a try, and make sure to keep the green and blue laser somewhere my kids can’t get at them.

Both resolution and contrast are essential for an image to appear sharp. In simple terms, resolution is the ability to transfer details, while contrast is the ability to distinguish between light and dark areas. Even if resolution is high, a low contrast will inhibit your ability to clearly see sample details. High-quality optics transfer more contrast at higher frequencies (i.e., at a higher resolution), so it is important to measure this ability in optics when designing an imaging system. This can be done through MTF.

Lens MTFdatabase

I was looking for some ~1W lasers for an experiment, but the ones that are legit 1W-ish and advertised as such are usually obscenely expensive, and that’s if they can be shipped.

Only 450nm blue exceeds 1W. Its around 1600 mw. The other colors are much less. Green is only 80-100 mw of visible green light. About 150 mw of Ir leaks out. Red is around 200 mw but its not that impressive. Purple is about 300 but it looks very weak. Dont think IR exists. If you remove crystal from green laser, you loose the focusing lens which is incorporated in that assembly. You will make an IR flashlight with a very divergent beam.

We provide optical and mechanical data to assist in the integration of Olympus components into final product designs. Custom objective lenses and optical assemblies are available when design requirements extend beyond off-the-shelf components.

Figure 8 below shows an example. Take a look at the MTF at the center and off-axis positions of the sensor. The MTF at the center position is 70%. The MTF of meridional at 5 mm from the center is 50%. Normally, the farther away from the center, the more the MTF deteriorates due to the effects of off-axis aberrations. In this example, the MTF of meridional becomes 20% at 10 mm from the center. For optimal performance, make sure to check the MTF at the image height required for the application while building your system.

Yes, good point. Always be responsible with these things. Most of these will be way overpowered than the 5mw listing. Only to pass customs. Actual power is a few hunderd mw up to 1W. Seriously potential for eye injuries. Never direct at people, pets, and especially plane pilots and vehicle drivers. Even if its far away enough not to cause eye damage it can still distract them and cause an accident. (Also illegal in a lot of countries.) If you get laser, use it responsibly, and dont be a jerk and ruin it for everyone because these things are awesome.

Yeah, my 900mW laser is blue, and wanted a little bit of an upgrade. Haven’t really seen anything in similar wattage in other colors.

Lens MTFchart

Considering I’m used to flashlight manufacturers lying about outputs that are actually far less than claimed, I’m a little surprised that for lasers it is the opposite, with manufacturers lying about outputs far higher than claimed.

I see JLasers has some very high powered lasers (up to 7W) based on the Convoy C8, M21A, and M21B bodies. Way overkill for me, but very cool (and dangerous) looking. And they have a 10440-powered model coming soon that looks like it might use a SF-348 body.

Yeah, this was back when I think GB was selling for cheap the hosts-of-color in the nice gift-boxes and metal switch. About the same price of the filled-in lights, but they’d come in the Cheap White Generic Cardboard Boxes, so kinda hard to gift. I was gonna go nuts and make bespoke lights (choice of emitter, driver, etc.), but still had too many left over.

OEM optical suppliers can provide MTF information and charts for optical components, enabling you to assess the optics for your system design.

In fact, it occurred to me that a Convoy T3 body with a laser producing probably in the 10-100mW range would be exactly what I want. I actually started looking into possible sources for laser diodes and drivers that might be possible to adapt to a T3 body. That took me to LaserPointerForums, which looks useful, although there’s more info there than I can sort through just yet.

An MTF curve can show you the difference between the ideal optical system and the constructed system at a glance. When comparing the MTFs of the following two optical systems (Figure 5), you can see that System 1 has higher performance than System 2 because it is closer to the diffraction limit value.

The modulation transfer function, or MTF, is a parameter used to evaluate the performance of a lens. MTF provides a quantitative and standardized way to characterize optical systems, so the metric is used by optical designers and microscopists alike to compare lenses and determine the ideal one for an imaging system.

Another useful way to use MTF charts it to check the MTFs of different optical components within a system, such as an objective and a tube lens. This enables you to see if there is any MTF deterioration due to one of the optical components. With this information, you can adjust the components to achieve the optimal performance needed for the system. For example, it is possible to calculate the MTF of an objective lens alone, a tube lens alone, and an optical system that combines an objective lens and a tube lens.

MTF is a good indicator when you want to compare the performance of different objective lenses since it shows which lens has a higher contrast at a certain spatial frequency. As we mentioned earlier, a higher contrast will lead to better image performance. MTF charts make it easy to compare the contrast of optics since you can visually see which MTF curve is higher.

His site is now offering a number of other builds using Convoy hosts so they can run continuously, but they’re also a fair bit more expensive.

In general, similar sagittal and meridional characteristics creates a more uniform image. This means that if the sagittal and meridional curves are closer to each other on an MTF chart, then the images will have more even image performance on both the X-axis (horizontal) and Y-axis (vertical). A gap, on the other hand, generally indicates an uneven image with aberrations. Ideally you want the curves to be closer to each other for more even image performance.

Looking at Figure 7 below, the MTF at the on-axis focus position is 60%, and the MTF at the off-axis focus position is 40%. You can see that the off-axis MTF has deteriorated by 20%. The acceptable numbers vary depending on the application. If the numbers are unacceptable, consider changing the design or switching to different optical components.

I can’t believe those are actual convoy flashlight hosts they made into lasers. They even say convoy on them. That’s hilarious.

The diffraction limit indicates the absolute limit of the resolution in an optical system. By comparing the diffraction limit value with the MTF of the lens system, it is possible to evaluate how close the performance of the lens system is to the theoretical value.

Optical MTF data is used for a range of instruments, including DNA sequencers, cell analyzers, slide scanners, and industrial inspection equipment. To help assist the optical design process, this white paper will explore MTF in detail and explain the different ways it can be used.

I got a JLasers 1.6W Blue laser for my last birthday… It’s pretty nuts considering it’s in a 14500 host. I’m deathly afraid to use it for anything other than pointing at stars though. Laser goggles are highly recommended.

It is somewhat slow (~30 seconds, hence the rising output graph in his video), and I suspect we’re not talking about single digit percentage accuracy, but I suspect more than adequate to compare relative safety.

Olympus discloses MTF data under the condition of an NDA (non-disclosure agreement). This data can be used to be build an optical system with higher optical performance.

I personally use the chinese blue laser. Its very powerful for about $50. They are sold under many names, mainly a gatling stlye laser and one that looks like a clone of the wicked laser. Green lasers are more expensive but far brighter. The blue lasers are usually direct diode. Green is usually a weaker DPSS which is like the cheap cat toy you mentioned. These leak a lot of infrared light and wont function in the cold. Direct diode green is better.

Figure 7. MTF curves at different focus positions (the peak of the curves) in the field of view. The gap between on the on-axis and off-axis curves indicates defocusing issues.

I figured testing laser power would be relatively complex and require some sort of expensive meter, but I looked up the one TTC is using, and it’s just $140. Apparently at low to medium power levels, it is as simple as applying a coating that absorbs visible light with good consistency across different wavelengths to a thermopile (basically a thermoelectric cooler operating in reverse) mounted on a heatsink. The resulting temperature increase generates an electrical signal that can correlated to power. The manufacturer of this “Laserbee” meter says they calibrate theirs against a much more expensive, commercial grade laser meter.

MTF lens

I actually found this thread because I identified a need at work for a laser pointer better than the weak button cell toy I have in a drawer at home. After some brief searching, I found the laser pointer world is filled with what appear to be the laser equivalents of Atomic Beam or the disposable Harbor Freight flashlights. But I want the laser equivalent of a Convoy T3: well made, usefully bright, but still easy on the wallet.

In most lenses, the contrast is higher at the center of the field of view than at the edges. For this reason, an MTF chart may also show curves in the sagittal and meridional directions. These curves illustrate how the contrast changes depending on the distance from the center of the image.

Knowing the MTF of optics under the right conditions will help you build the optical system you need for your instrument design. Note that when evaluating an optical system with MTF, it is necessary to select a sensor with the optimal pixel pitch and Nyquist frequency. For further details, please refer to our white paper, What to Consider When Choosing a Microscope Camera.

Nice! I don’t have that many Convoy flashlights, but I do appreciate Convoy. I prefer flashlights that are somewhat throwy, and Convoy offers plenty of great choices for what I like.

Lens mtf measurementformula

His Thorfire C3 based line are the ones that intrigue me the most. They’re not quite as powerful, but he has a 3.5W model.

Consider the MTF graph below (Figure 6) as an example. You can see the MTF performance of Optics A is better than Optics B since the curve is higher. This visual information can help you select the right objective lens for your system design.

Lens mtf measurementchart

MTF can be calculated for single wavelengths (monochromatic light) or for white light, depending on your application. For instance, laser-based applications for fluorescence or multiphoton imaging may require MTF data for single wavelengths while generic imaging applications may require MTF data for white light. MTF charts for each wavelength can also be compared against each other to determine the overall device performance.

An MTF chart can also show you how sensitive the optics are to defocusing by illustrating the MTF difference between on-axis and off-axis focus positions. The on-axis focus position refers to the center of the field of view that provides a sharp, focused image. The off-axis focus position refers to a position at the corner of the field.

Image height is the distance from the center to the edge of the image. An MTF chart enables you to visually determine the ideal image height at the sensor position of the optical system. You can also check the performance difference between the on-axis and off-axis sensor positions.

Ideally the MTF curve of the off-axis position should be as close as possible to that of the on-axis position to produce a focused image. A gap between the on-axis and off-axis curves (as shown in Figure 7 below) indicates defocusing issues due to aberrations.

That was way back when everything and its grandmother was the dreaded “XML-T6”. Just typing that actually physically pains me.

We offer infinity-corrected objective lenses for a variety of optical-mechanical systems. Specialties include visible and near-IR wavelengths, long working distances, immersion, coverslip correction, and white light interferometry lenses.

Lens mtf measurementcalculator

Sagittal indicates the performance in the radial direction (from the center to the corner of the image), and meridional indicates the performance in the concentric direction (circular). The contrast in the sagittal and meridional directions change due to the influence of off-axis aberrations (i.e., optical errors at different field points), such as coma and astigmatism.

Lens MTFcomparison

So naturally I thought, “I bet some folks on BLF have already gone down the laser rabbit hole and can make some recommendations.” I’m glad I looked.

In the MTF chart in Figure 2, the field of view is fixed, the horizontal axis shows the spatial frequency (lp/mm), and the vertical axis shows the contrast. The chart shows that 50% contrast can be achieved with this lens at a spatial frequency of 30 lp/mm.

And they have a wide range of 14500-powered lasers based on the stainless steel version of the Ultrafire C3 body. Some even have multi-mode drivers. That is close to perfect. They aren’t as cheap as a Convoy flashlight, but the pricing seems pretty good for a niche product. The main drawback I see is the 638 nm version, which is probably the color I’d want to start with, is 700mW, which I suspect is quite a bit more powerful than I would want.

Be careful with eBay lasers or AE lasers. These Chinese ones are often way over the 5mW limit for class II and class III which are the max for legal import. They’re often hundreds of times more powerful, some up to 3W. Some, especially the blue/purple can leak invisible near IR light that’s very detrimental to your unprotected vision. There’s also incidental reflection (especially with green) off some surfaces that can damage your eyes without ever being ‘shined’ directly. If you’ve got to have a laser over 200mW, get some proper laser goggles. Your eyes will thank you.

MTF shows how the contrast on the surface of the object is reflected on the image plane. Contrast is calculated using the following formula. The ratio of contrast between the object surface and the image plane is MTF.

Modulation transfer function

Figure 5. MTF curves of two optical systems. The side-by-side comparison enables you to see which system is closer to the diffraction limit.

Figure 6. MTF curves of two different objectives. Optics A has a higher curve than Optics B, indicating that it has better optical performance.

Figure 2. Example MTF chart showing contrast (MTF) vs. spatial frequency. The chart shows 50% contrast at a spatial frequency of 30 lp/mm.

EDIT this counts for not only gatling style lasers but all cheap chinese lasers in a big host eg. 18650,16340 or 26650. Depending on your choice of host, the blue 1w laser will be around $50-75 depending if you get only the laser or a kit with cheap chinese batteries and accessories

I can’t personally vouch for JLasers, but in addition to laser pointers made from Convoy and Ultrafire bodies, he sells laser power meters. Hopefully the owner of that site is verifying his own products.

MTF measures a lens’ ability to transfer the contrast of a sample to an image using spatial frequency (resolution). Spatial frequency indicates the number of line pairs (i.e., one black and one white line) per millimeter (lp/mm). Generally, various charts with equally spaced, alternating black and white lines (Figure 1) are used to measure the MTF of a lens. The contrast is then plotted on an MTF chart against the spatial frequency, as shown in Figure 2 below.

It looks like he has a slightly older video testing Amazon laser pointers, showing that $15 buys a 3-pack of laser pointers advertised as toys that in reality can be as much as 16x the maximum output legally allowed to sold as a laser pointer in the US.