If a Green 532 is the brightest then what's second brightest?

Cyparagon · Aug 29, 2015

Gabe said:
I was assuming, I think along with everyone here, that he meant at the same power.

That's never really the case though, is it? Grab an average laser of each color, and your powers vary by several orders of magnitude.

A green HeNe is brighter than a 520nm diode by your assumption.

Gabe said:
I remembered a few people saying their 20mW 561nm were as bright or brighter than a 30mW 532.

They'd be wrong (unless they've got mutant retinas). The science says no.

Atomicrox said:
Here's a chart of the normalized curves, including one corrected for scattering (1/λ^4)

Thanks! Do you have a chart or site to go with that?

I'm not sure of the accuracy on the ends though. It's been my experience that a violet beam is noticeably brighter than a red beam of equal power, and I think everyone that's seen both would agree. But the CIE1978 curve also has this flaw on the ends.

micheal rosen · Aug 29, 2015

Cyparagon said:
I'm not sure of the accuracy on the ends though. It's been my experience that a violet beam is noticeably brighter than a red beam of equal power, and I think everyone that's seen both would agree. But the CIE1978 curve also has this flaw on the ends.

Idk, my 405 and 638 both have roughly similar output power, I'd say the beams are roughly equal in brightness too, the violet may be slightly brighter though.

Atomicrox · Aug 29, 2015

I plotted that on Excel, based on the data below (don't remember the source, but it was most likely posted here on LPF):

Code:

λ	CIE 1931 V(λ) (photopic)	CIE 1978 V(λ) (photopic)	CIE 1951 V ′(λ) (scotopic)		Rayleigh factor (no units)	1978 corrected for scattering
360	0.000003917	0			5.305093545	0
365	0.000006965	0			5.020322209	0
370	0.00001239	0			4.754404771	0
375	0.00002202	0			4.505862953	0
380	0.000039	0.0002	0.000589		4.273351954	0.00085467
385	0.000064	0.00039556	0.001108		4.05564685	0.001604252
390	0.00012	0.0008	0.002209		3.851630537	0.003081304
395	0.000217	0.0015457	0.00453		3.660283017	0.005657699
400	0.000396	0.0028	0.00929		3.480671875	0.009745881
405	0.00064	0.0046562	0.01852		3.311943783	0.015421073
410	0.00121	0.0074	0.03484		3.153316929	0.023334545
415	0.00218	0.011779	0.0604		3.004074249	0.035384991
420	0.004	0.0175	0.0966		2.863557366	0.050112254
425	0.0073	0.022678	0.1436		2.731161169	0.061937273
430	0.0116	0.0273	0.1998		2.606328944	0.07115278
435	0.01684	0.032584	0.2625		2.488547997	0.081086848
440	0.023	0.0379	0.3281		2.377345724	0.090101403
445	0.0298	0.042391	0.3931		2.272286066	0.096324479
450	0.038	0.0468	0.455		2.172966316	0.101694824
455	0.048	0.052122	0.513		2.079014234	0.10836238
460	0.06	0.06	0.567		1.990085441	0.119405126
465	0.0739	0.072942	0.62		1.905861064	0.139017318
470	0.09098	0.09098	0.676		1.826045596	0.166133628
475	0.1126	0.11284	0.734		1.75036496	0.197511182
480	0.13902	0.13902	0.793		1.678564755	0.233354072
485	0.1693	0.16987	0.851		1.610408651	0.273560118
490	0.20802	0.20802	0.904		1.545676945	0.321531718
495	0.2586	0.25808	0.949		1.484165232	0.383033363
500	0.323	0.323	0.982		1.4256832	0.460495674
505	0.4073	0.4054	0.998		1.370053533	0.555419702
510	0.503	0.503	0.997		1.317110903	0.662506784
515	0.6082	0.60811	0.975		1.266701058	0.77029358
520	0.71	0.71	0.935		1.218679974	0.865262782
525	0.7932	0.7951	0.88		1.172913097	0.932583203
530	0.862	0.862	0.811		1.129274629	0.97343473
535	0.91485	0.91505	0.733		1.087646887	0.995251284
540	0.954	0.954	0.65		1.047919713	0.999715406
545	0.9803	0.98004	0.564		1.009989922	0.989830523
550	0.99495	0.99495	0.481		0.973760809	0.968843317
555	1	1	0.402		0.939141683	0.939141683
560	0.995	0.995	0.3288		0.906047448	0.90151721
565	0.9786	0.97875	0.2639		0.874398206	0.855817244
570	0.952	0.952	0.2076		0.844118904	0.803601197
575	0.9154	0.91558	0.1602		0.815138997	0.746324963
580	0.87	0.87	0.1212		0.78739214	0.685031162
585	0.8163	0.81623	0.0899		0.760815908	0.621000769
590	0.757	0.757	0.0655		0.735351534	0.556661111
595	0.6949	0.69483	0.0469		0.710943661	0.493984984
600	0.631	0.631	0.03315		0.687540123	0.433837818
605	0.5668	0.56654	0.02312		0.665091735	0.376801071
610	0.503	0.503	0.01593		0.643552096	0.323706704
615	0.4412	0.44172	0.01088		0.622877418	0.275137413
620	0.381	0.381	0.00737		0.603026352	0.22975304
625	0.321	0.32052	0.00497		0.583959839	0.187170808
630	0.265	0.265	0.003335		0.565640961	0.149894855
635	0.217	0.21702	0.002235		0.548034814	0.118934515
640	0.175	0.175	0.001497		0.531108379	0.092943966
645	0.1382	0.13812	0.001005		0.514830409	0.071108376
650	0.107	0.107	0.000677		0.499171318	0.053411331
655	0.0816	0.081652	0.000459		0.484103084	0.039527985
660	0.061	0.061	0.0003129		0.469599155	0.028645548
665	0.04458	0.044327	0.0002146		0.455634361	0.020196904
670	0.032	0.032	0.000148		0.442184829	0.014149915
675	0.0232	0.023454	0.0001026		0.429227914	0.010067112
680	0.017	0.017	0.0000715		0.416742122	0.007084616
685	0.01192	0.011872	0.0000501		0.404707044	0.004804682
690	0.00821	0.00821	0.00003533		0.393103297	0.003227378
695	0.005723	0.0057723	0.00002501		0.381912463	0.002204513
700	0.004102	0.004102	0.0000178		0.371117035	0.001522322
705	0.002929	0.0029291	0.00001273		0.360700365	0.001056527
710	0.002091	0.002091	0.00000914		0.350646618	0.000733202
715	0.001484	0.0014822	0.0000066		0.340940726	0.000505342
720	0.001047	0.001047	0.00000478		0.331568347	0.000347152
725	0.00074	0.00074015	0.000003482		0.32251582	0.00023871
730	0.00052	0.00052	0.000002546		0.313770138	0.00016316
735	0.0003611	0.00036093	0.00000187		0.305318903	0.000110199
740	0.0002492	0.0002492	0.000001379		0.297150298	7.40499E-05
745	0.0001719	0.00017231	0.000001022		0.289253058	4.98412E-05
750	0.00012	0.00012	0.00000076		0.281616435	3.3794E-05
755	0.0000848	0.00008462	0.000000567		0.274230176	2.32054E-05
760	0.00006	0.00006	0.000000425		0.267084497	1.60251E-05
765	0.0000424	0.000042446	3.196E-07		0.260170055	1.10432E-05
770	0.00003	0.00003	2.413E-07		0.253477928	7.60434E-06
775	0.0000212	0.00002121	1.829E-07		0.246999594	5.23886E-06
780	0.00001499	0.000014989	0.000000139		0.240726909	3.60826E-06
785	0.0000106	0.000010584			0.234652088	2.48356E-06
790	7.4657E-06	7.4656E-06			0.228767689	1.70789E-06
795	5.2578E-06	5.2592E-06			0.223066593	1.17315E-06
800	3.7029E-06	3.7028E-06			0.217541992	8.05514E-07
805	2.6078E-06	2.6076E-06			0.212187369	5.533E-07
810	1.8366E-06	1.8365E-06			0.206996486	3.80149E-07
815	1.2934E-06	0.000001295			0.201963373	2.61543E-07
820	9.1093E-07	9.1092E-07			0.197082308	1.79526E-07
825	6.4153E-07	6.3564E-07			0.192347814	1.22264E-07

I agree it's definitely very off at 405nm and the infrared, but it seems to agree roughly with my experience from 445nm to 685nm. It's certainly an improvement on the '31 data.

If I'm allowed to speculate, I think the "error" at 405nm is due to the fact that in complete darkness our eyes tend to pick that WL in scotopic mode. To corroborate that, my <100mW beams look far more grayish than the beam of the 500mW laser.

Gabe · Aug 29, 2015

Cyparagon said:
That's never really the case though, is it? Grab an average laser of each color, and your powers vary by several orders of magnitude.

A green HeNe is brighter than a 520nm diode by your assumption.

They'd be wrong (unless they've got mutant retinas). The science says no

Yerp yerp, I pointed out the flaws in my methodology, maybe you missed that part. Or read before I edited. By my assumption, yes, a HeNe is brighter than a 520. ONLY IF, the HeNe is much closer to our peak spectral sensitivity than the 520, and I they are outputting the same amount of power. Otherwise, the comparison would be useless, changing more than one variable at a time. I was pretty confident that OP was implying which colour is next brightest mW to mW, because if power was part of the question, the question is useless. One could say that a 445nm laser appears brighter to the human eye than a 532nm laser, so long as they leaves out the fact that the blue laser is 1W and the green laser is 5mW. You know what I'm saying? Also, you're right on the count of people seeing '20mW' of 561 as bright as 30mW of 532. I think the reason they said that is probs because the 561 was over spec, as lasers from CNI usually are. I've even seen that same type of laser (20mW 561) be actually metered, and it registered around 50mW. So it's likely that this guys comparison has the 561 be more powerful than he thought. I can pull up the thread I'm talking about if you'd like.

Cyparagon · Aug 29, 2015

micheal rosen said:
Idk, my 405 and 638 both have roughly similar output power, I'd say the beams are roughly equal in brightness too, the violet may be slightly brighter though.

Okay. Now find your two wavelengths on the plot. What does the plot predict?

Atomicrox said:
If I'm allowed to speculate, I think the "error" at 405nm is due to the fact that in complete darkness our eyes tend to pick that WL in scotopic mode.

If you can see color, you're not in scotopic mode.

F16-02%20Photopic%20mesopic%20scotopic%20vision.jpg

Maybe mesopic. But even mesopic vision doesn't begin until under 20 lux. 20 lux is a lot dimmer than most people have their houses. (I believe 150 lux is average)

micheal rosen · Aug 29, 2015

Cyparagon said:
Okay. Now find your two wavelengths on the plot. What does the plot predict?

The one atomicrox (or something, im doing this on a phone) posted says 405nm should have a much dimmer beam, I think. It clearly isnt quite accurate. I don't get into the whole perceived brightness thing allot, especially not in detail using the different vision types and all, so I'm not really sure.

Atomicrox · Aug 29, 2015

Cyparagon said:
Maybe mesopic. But even mesopic vision doesn't begin until under 20 lux. 20 lux is a lot dimmer than most people have their houses. (I believe 150 lux is average)

That's the thing, in total darkness a weak 405nm looks grey as opposed to violet.

Gabe · Aug 29, 2015

Atomicrox said:
That's the thing, in total darkness a weak 405nm looks grey as opposed to violet.

I was just about to say that, I remember being able to see the beam on my "5mW" 405nm, and I remember it being grey rather than purple.

RedCowboy · Aug 30, 2015

I wonder is you were to sit in a dark room and let your eyes adjust, then view lasers across the 500-600nm range each at only .25mw output if the one that appeared the brightest would be the same as it would if the same lasers were running at 50mw output.

What if the output of each laser was slowly raised all together the same amount, would 1 be perceived as brighter than what was previously thought to be brightest?
In essence I'm wondering if a bright other than red laser has enough scattered energy to shift your scopotopic/mesopic/photopic status.
Some may see one as brighter than the other at night based on the output of the laser and where they naturally shift.

Our eyes are amazing, they actually use pulse code modulation to get all the information to fit on our optic nerve.
Our brains are heavily involved in interpreting as well.

Recently when viewing a 445nm then a 465nm next to it I experienced a perceived change in the color of the 445nm.
It was blue or at least it looked blue, but after seeing the 465nm next to it my brain tells me the 445nm is purple, not royal purple but a lot more than the moment before.

Cyparagon · Aug 30, 2015

Atomicrox said:
That's the thing, in total darkness a weak 405nm looks grey as opposed to violet.

I suppose, sometimes. But why don't other colors appear this way in the dark? Also, it doesn't account for dimly-lit areas, or instances where you're comparing a red beam.

NightExplorer96 · Aug 30, 2015

^I believe it's due to how sensitive our eyes are. As im sure you know, our eyes consist of rods & cones, the rods only operate to detect white, black & grey whilst the latter detects colors.

When the light becomes too dim, or insufficient light is entering the eye our cones cannot function as well, resulting in only our rods working. My guess would be since 405 is borderline what we can see(even at high powers) the lower end power outputs don't produce sufficient light for our eyes to see clearly enough, resulting in a greyish color. Red lasers, while still being quite dim to our eyes, are still brighter(650/635) then a 405 of similar output power.

-Alex

Atomicrox · Aug 30, 2015

Cyparagon said:
I suppose, sometimes. But why don't other colors appear this way in the dark? Also, it doesn't account for dimly-lit areas, or instances where you're comparing a red beam.

True. I guess other colors don't appear this way because they are bright enough to trigger color vision. If you pay attention you''ll notice that the beam from 405nm is brighter than 650nm, but the dot is way dimmer.

RedCowboy said:
Recently when viewing a 445nm then a 465nm next to it I experienced a perceived change in the color of the 445nm.
It was blue or at least it looked blue, but after seeing the 465nm next to it my brain tells me the 445nm is purple, not royal purple but a lot more than the moment before.

Happens to me as well. Look at the dots far away and try adding a 405nm and it will look like a weird magenta-ish instead of the usual violet.

NightExplorer96 · Aug 31, 2015

Atomicrox said:
True. I guess other colors don't appear this way because they are bright enough to trigger color vision. If you pay attention you''ll notice that the beam from 405nm is brighter than 650nm, but the dot is way dimmer.

I've never experienced it, but would the same phenomenon which occurs with low powered 405's be similar to lasers which near the IR range of the Electromagnetic Spectrum?

-Alex

Cyparagon · Aug 31, 2015

LeHap said:
lasers which near the IR range of the Electromagnetic Spectrum?

The word you're searching for is red

NightExplorer96 · Aug 31, 2015

Cyparagon said:
The word you're searching for is red

-Alex

Atomicrox · Aug 31, 2015

LeHap said:
I've never experienced it, but would the same phenomenon which occurs with low powered 405's be similar to lasers which near the IR range of the Electromagnetic Spectrum?

-Alex

I don't think I've ever seen red or IR as grey.

If a Green 532 is the brightest then what's second brightest?

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